vvEPA
United States
Environmental Protection
Agency
Office of Air Quality
Planning and Standards
Research Triangle Park, NC 27711
EPA-454/R-95-007
'July 1991
Air
REVIEW OF
SURFACE COAL MINING
EMISSION FACTORS
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EPA-454/R-95-007
REVIEW OF
SURFACE COAL MINING
EMISSION FACTORS
U.S. Environmental Protection Agency
Region 5, Library (PL-12J)
77 West Jackson Boulevard, 12th Floor
Chicago, IL 60604-3590
Emission Factor And Inventory Group
Emissions, Monitoring, And Analysis Division
Office Of Air Quality Planning And Standards
U. S. Environmental Protection Agency
Research Triangle Park, NC 27711
July 1991
-------
This report has been reviewed by the Office Of Air Quality Planning And Standards, U. S.
Environmental Protection Agency, and has been approved for publication. Any mention of trade
names or commercial products is not intended to constitute endorsement or recommendation for use.
EPA-454/R-95-007
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PREFACE
This interim report was prepared by Midwest Research Institute under U.S.
Environmental Protection Agency (EPA) Contract No. 68-DO-0137, Work
Assignment No. 10. The principal author of this report is Dr. Greg Muleski; he
was assisted by Mr. Robert Dobson and Ms. Karen Connery. Mr. Dennis
Shipman of the Office of Air Quality Planning and Standards serves as the EPA's
technical monitor of the work assignment.
Approved:
Charles F. Holt, Ph.D., Director
' Engineering and Environmental
Technology Department
July 11, 1991
MRI-OTS\R9800-10 31
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CONTENTS
1. Introduction 1
2. Overview of the Surface Coal Mining Industry 3
3. Overview of Emission Sources and Measurements at Surface Coal
Mines 14
Important Emission Sources 14
Field Measurements at Surface Coal Mines 16
4. Emission Factors For Use at Surface Coal Mines 25
AP-42 Emission Factors and Predictive Equations 25
Evaluation of Alternative Emission Factors 28
5. Summary and Recommendations 39
6. References 47
MRI-OTS\R9800-1031
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SECTION 1
INTRODUCTION
As part of the Clean Air Act Amendments of 1990, the U.S. Environmental
Protection Agency has the need to review and revise emission factors for criteria
pollutants. Specifically, Section 234 of Title I requires field testing for emission
factors for surface coal mines. This interim report provides a review of currently
available, field-measurement-based emission factors for surface coal mines
(SCMs) and describes field testing needs to address gaps in the data base.
A principal purpose of the review is to provide a common basis for
discussion at a workshop to be held in Kansas City, Missouri, during
August 1991. This report has been sent to interested parties who have been
invited to participate at the workshop. These parties include coal and mining
industry groups, environmental organizations, and state and federal agencies for
mining activities and environmental protection.
Throughout the report, the review focuses on the strengths and
weaknesses of the available data, thus identifying major gaps within the data
base.
The remainder of this report is structured as follows. Section 2 presents a
brief overview of the surface coal mining industry. Section 3 describes the types
of emission sources found at SCMs, emphasizing operating characteristics that
are potentially different between various parts of the country. In Section 4, the
methods available to estimate emissions from SCM sources are discussed and
major gaps within the data base are identified. Section 5 summarizes the results
of the review and presents a series of recommendations. Section 6 lists the
references cited in the report.
Emission factors relate the amount of mass emitted per unit activity of the
source. For example, a common unit for travel related emissions is "Ib/vmt," or
pounds emitted per vehicle mile traveled. Thus, the "source extent" on a road is
measured in terms of the total miles traveled by vehicles over the road. Similarly,
if a material handling emission factor is expressed in terms of pounds emitted
per ton (or, cubic yard), then the source extent is measured in terms of the tons
or cubic yards of material transferred.
MR!-OTS\R9800-1031
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The following discussion uses English— such as pounds and miles— rather
than metric (SI) units— such as kilograms and kilometers. This approach has
been taken because it is believed that individuals taking part in the Kansas City
workshop will be more familiar with common English units.
The principal pollutant of interest in this report is "particulate matter" (PM),
with special emphasis placed on "PM-10"— particulate matter no greater than
10 MmA (microns in aerodynamic diameter). PM-10 is the basis for th<= current
National Ambient Air Quality Standards (NAAQSs) for paniculate matter as well
as the EPA's Prevention of Significant Deterioration (PSD) increments.
PM-10 thus represents the size range of particulate matter that is of the
greatest regulatory interest. Nevertheless, formal establishment of PM-10 as the
standard basis is relatively recent, and virtually all surface coal mine field
measurements reflect a particulate size other than PM-10. Other size ranges
employed in this report are1
TSP Total Suspended Particulate, as measured by the standard high-
volume (hi-vol) air sampler. TSP was the basis for the previous
NAAQSs and PSD increments. TSP is a relatively coarse size
fraction. While the capture characteristics of the hi-vol sampler are
dependent upon approach wind velocity, the effective D50 (i.e.,
50% of the particles are captured arid 50% are not) varies roughly
from 25 to 50
SP Suspended Particulate, which is used as a surrogate for TSP.
Defined as PM no greater than 30 /umA. Also denoted as "PM-30.
IP Inhalable Particulate, defined as PM no greater than 15
Throughout the late 1970s and the early 1980s, it was clear that
EPA intended to revise the NAAQSs to reflect a size range finer
than TSP What was not clear was the size fraction that would be
eventually used, with values between 7 and 15 umA frequently
mentioned. Thus, many field studies at SCMs were conducted
using IP measurements because it was believed that would be the
basis for the new NAAQS. IP may also be represented by
"PM-15."
FP Fine Particulate, defined as PM no greater than 2.5 jimA Also
denoted as "PM-2.5."
It is again emphasized that this is an interim report whose purpose is to
provide a common basis for further discussion at the Kansas City workshop. It
is probable that several issues in addition to those presented here will be raised
at the workshop This report, then, is an initial focus point for constructive
discussions and, in that sense, represent? very much a '-work in progress.'
MRI-OTS\R980C
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SECTION 2
OVERVIEW OF THE SURFACE COAL MINING INDUSTRY
Coal is mined in 26 states. The leading coal producers are Kentucky,
Wyoming, West Virginia, Pennsylvania, Illinois, Texas, Virginia, and Ohio; these
states account for approximately 75% of U.S. coal production.1
United States coal reserves total approximately 490 billion tons. Of that
total, 330 billion tons are estimated to be minable by underground methods and
160 billion tons by surface methods. Since the early 1970s surface mines have
accounted for more than half of the total coal produced. In 1985 coal was
produced by both underground and surface mining in 15 of the 26
coal-producing states, with the remaining 11 having surface mines only.
For discussion purposes in this report, the U.S. coal mining industry has
been divided into three major regions:
• Appalachian Region
Northern Appalachia
Central Appalachia
Southern Appalachia
• Midwest Region
• West Region
Powder River
Rocky Mountain
(The small amount of coal mining in Alaska is not considered in this report.)
Each region and subregion is briefly described in the following paragraphs.2
Northern Appalachia includes the states of Maryland, Pennsylvania, Ohio,
and northern West Virginia. Coal production is largely high to medium sulfur
bituminous coal. Eastern Pennsylvania is home to the only working anthracite
mines in the United States. Bituminous coal production in the Northern
Appalachian Region totaled 155.5 million tons in 1985 of which 62.2 million tons
were surface mined and 93.4 were mined using underground methods (see
Figure 1). Northern Appalachia is characterized by a small number of
underground mines and a large number of very small surface operations.
MRI-OTS\R9800-1031 J
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NCHTHEr.h APPALACHlA U1NE3 !N IS
!!
*c>
4CS
18C -
IOC -
>aoo
teo-aeo
«0-',OC
Tn)
16-10
100
(b)
NORTHERN APPALACHIA U1N5S 19E5
(WMQC
•0 -
au
iao-aoo
'106
Figure v Histograms showing (a) number of mines and (b) total annual
production as a function of mine size for the Northern Appalaohh
Region in 1985 From Reference 3
MRi-OTS -r-e',
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Central Appalachia includes areas in Southern West Virginia, Virginia, the
eastern half of Kentucky, and Northern Tennessee. The coal reserve base is
approximately 52 billion tons of bituminous coal, of which 7.9 billion tons are
minable by surface methods and 44.1 billion tons are recoverable by
underground methods. Production in 1985 was 232.4 million tons of which
72.1 million tons were surface mined (see Figure 2).
Central Appalachia is characterized by a large number of "mom and pop"
surface and underground mines. The mines are termed in this way due to the
small, informal, family nature of most of the operations.
Southern Appalachia includes the mining areas of Alabama and southern
Tennessee. The reserve base totals 4.9 billion tons of bituminous coal split
equally between surface and underground mining methods. A 1 -billion ton
reserve of lignite is not presently mined. Production of bituminous coal in
Southern Appalachia totaled 30.1 million tons in 1985 of which 13.9 million tons
were surface mined. Southern Appalachia is characterized by a few producers
with large capacity underground mines, and medium to small surface mines (see
Figure 3).
The Midwest Region includes regions of Illinois, Indiana, and
western Kentucky and is also known as the Illinois Coal Basin. The entire
110 billion ton reserve base is bituminous. Of this total, 21 billion tons are
surface minable. Coal production in the Midwest totaled 131.4 million tons in
1985 (74.1 million tons surface mined).
The Midwest Region is characterized by large corporate mines. This is
particularly true of underground mines. As shown in Figure 4, Midwest surface
mines are quite uniformly distributed over a very broad range of annual
production values.
Western coal mining is divided into two areas, the Rocky Mountain Region
and the Powder River Basin. The Powder River Basin includes Montana and
Wyoming. The reserve base ranges from lignite to reasonably high quality
bituminous. The total reserve base is 189.4 billion tons, of which 168 billion tons
is classified as subbituminous, 16 billion tons as lignite, and 6 billion tons as
bituminous. Production in the Powder River Basin totaled 174 million tons in
1985, virtually all of which was surface mined (Figure 5). The Powder River Basin
is characterized by very large surface mines, with the largest mines in the United
States in this region.
The Rocky Mountain Region includes the states of Colorado, Utah,
New Mexico, and Arizona. This region has reserves in four different
classifications: anthracite, bituminous, subbituminous, and lignite. Recoverable
reserves total 18.5 billion tons, of which 8 billion tons are considered minable by
surface methods.
MRI-OTS\R9800-10 31
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(a)
CZN7RM. APPALAOilA WINES IN 15ZS
ice -i
(b)
CENTRAL APPALACHIA MINE PRODUCTION 1985
t i .
(ThMMMI !•»)
SURTACC
Figure 2. Histograms showing (a) number of mines and (b) total annual
production as B function of mine size for the Central Appalachia
Region in 1985 From Reference 3.
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I
2
(a)
SCUTHEHN AFrALACKIA MINES IN 1 =3c
SOUTHERN APPALACH1A MINES 19S5
PTOOUCTON HT MMUN. WOBUCMW MNd
\ x \
\ \\
>«00
.100-200
ao-ioo
10-50
Figure 3. Histograms showing (a) number of mines and (b) total annual
production as a function of mine size for the Southern Appalachia
Region in 1985. From Reference 3.
MRI-OTS\R9800-1031
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n
w
2
V. e
(a)
Nuijsc"^ '"c" vjirwc"^"" utvi~~
*WmMM.. w* iMlw7Y^««t MiliM«
BY ANNUM. PMCCUCTX
IN
>SOO 300-000 100-200
PKCOUCTCN RANGE
(b)
50-100
TMB)
10-30
MIDWEST COAL MINE PRODUCTION 1985
BT ANNUM. ntOOUCnON KANCE
11.7
1.1
>SOO
200-900
100-200
50—100
10-90
IC^OK IWMCC CDwuMnd
Figure 4. Histograms showing (a) number of mines and (b) total annual
production as a function of mine size for the Midwest Region in
1985. From Reference 3,
8
MRI-OTS\R9BOCM
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§
(a)
I2 IN
1»
'.3
>*oo
200-aoo
100-200
ao-ico
10-80
(b)
POWDES RIVE? BASIN'MINE FnODUCnCN 1985
BY JMMUN. mCSUOON MH6E
1.1
0.1
0.1
>soo
200-900
100-200
90-1OO
10-90
Figure 5. Histograms showing (a) number of mines and (b) total annual
production as a function of mine size for the Powder River Basin
in 1985. From Reference 3.
MRI-OTS\R9800-1031
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Coal production in the Rocky Mountain Region totaled 61.9 million tons in
1985 of which 42 million tons were surface mined. The total consisted of
bituminous and subbituminous coal. Large surface operations and large
underground operations characterize the region (see Figure 6).
Tables 1 and 2 provide summary information for the 1985 United
States coal production in the Appalachian/Midwest and West regions,
respectively.
In summary, the number of mines increases and the average size
decreases as one considers U.S. surface coal mines from east to west. The
Appalachian Region has many small surface operations while the relatively few
western mines are almost all very large. The Midwest Region represents the
transition between the two extremes, with surface mines in all size ranges
relatively common.
Approximately 50% of the coai surface mined in the United States is from
eastern regions, where mines tend to be relatively small. As will be seen in the
next section, emissions from eastern SCMs have not been considered to any
great extent. Consequently, potential differences in PM emissions due not only
to the different size of mines, but also different climate factors in the east, have
not been fully characterized.
MRI-OTS\R9800- ,1
10
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«
I
\
(a)
ySEn Or nCCXY MOUNTAIN MINSS IN ",=££
10 -
a H
k
v/// //
xoo
-900
1CO-2X 50— ICC
1C-SO
ueoecuw
(b)
RCCKY MOUNTAIN WINE rRCSUCTlCN IN 1SS5
BY MOUM.
. ii--*
>B33
20G-SCO 109-SO 90—ICQ
10-50
Figure 6. Histograms showing (a) number of mines and (b) total annual
production as a function of mine size for the Rocky Mountain
Region in 1985. From Reference 3.
MRI-OTS\R9800-1031
11
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Table 1. EASTERN AND MIDWESTERN UNITED STATES COAL PRODUCTION STATISTICS
Eastern coal production (tons x 10^
Region
Northern Appalachia
Central Appalachia
Soutnero Appalachia
Midwest
Pennsylvania
Anthracite
Totals
Total
155,532
232,380
30,122
131,415
4,281
553,730
Underground
93,367
160,296
16,233
57,303
440
327,639
Percent of
total (%)
60.0
69.0
53.9
43.6
10.3
59.2
Surface
62,165
72,083
13,889
74,112
3,841
226,091
Percent of
total (%)
40.0
31.0
46.1
56.4
89.7
40.8
Ave. mine size (tons/yr)
Underground
472,000
127,000
507,000
939,000
49,000
--
Surface
103,000
108,000
158,000
481,000
55,000
-
Mnt.OTS\R980O-1031
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Table 2. WESTERN UNITED STATES COAL PRODUCTION STATISTICS
Western coal production (tons x 103) Ave. mine size (tons/yr)
Percent of Percent of
Region Total Underground total (%) Surface total Underground Surface
Rocky 61,876 19,925 32.2 41,951 67.8 510,000 1,824,000
Mountain
Powder River 173,997 1,058 0.6 172,939 99.4 1,058,000 4,941,000
Basin
Totals 235,873 20,983 8.8 214,890 91.2
MHI-OTS\R9800-10 31
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SECTION 3
OVERVIEW OF EMISSION SOURCES AND MEASUREMENTS
AT SURFACE COAL MINES
Throughout the surface mining process—from initial removal of topsoil until
final reclamation—paniculate matter (PM) may be emitted from a variety of
operations. This section (a) discusses major PM emission sources at surface
coal mines and (b) provides a short history of field measurement of those
emission sources.
IMPORTANT EMISSION SOURCES
Table 3 summarizes particulate matter emission sources typically found at
surface coal mines; the operations listed in the table are largely sequential. All
sources may be present simultaneously throughout different areas at any one
mine.
Clearly, PM sources vary in importance not only from one mine to
another—depending on, say, strip ratios or the type of equipment used (power
shovel, dragline, bucket wheel excavator rBWED—but also from one time to
another at the same mine—for example, when haul distances and hence
haulage-related emissions are the greatest.
Several prior studies have examined, in general terms, the relative
importance of different emission sources at SCMs. Inventories of hypothetical
examples as well as of actual mines indicate that typically over half (roughly 60%
to 90%) of the total suspended particulate (TSP) emission rate is due to the
following four traffic-related sources:
• scraper travel
coal haul trucks
• overburden haul trucks
• general (light and medium duty) traffic
Not all of the four sources are necessarily important at every mine. For
example, overburden haul trucks are not used at a dragline mine; in that case,
overburden removal by dragline becomes far more important. Also, general
traffic might not be important at, say, small mines with deep coal seams.
. . MRI-OTS\R9800-10.31
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Table 3. SUMMARY OF MAJOR EMISSION SOURCES AT
SURFACE COAL MINES
Topsoil related activities
• Removal
• Scraper travel
• Material handling and storage activities
• Replacement
Overburden related activities
• Drilling
• Blasting
• Removal
• Truck haulage
• Material handling and storage activities
• Replacement
• Dozer activity
Coal seam activities
• Drilling
• Blasting
• Loading
• Truck haulage
• Truck unloading
* Processing (crushing, screening, etc.)
• Material handlinn snd storage activities
• Dozer activity
• Loadout for transn
Genera! activities
• Vehicle travel
• Road grading
• Wind erosion of open areas and
materials in storage
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In very general terms, the four traffic-related sources listed above plus
overburden removal by dragline should account for roughly 70% of total TSP
emissions at most large surface mines.3
FIELD MEASUREMENTS AT SURFACE COAL MINES
Since 1973, production in U.S. western mines has more than tripled.1-2
The expansion is in large part the result of events during the early 1970s: the
original Clean Air Act resulted in high demand for low-sulfur western coals, and
the 1973 oil embargo stressed the importance of energy independence and
spurred mining activities. Thus, the development of large western SCMs was
accompanied by a more widespread interest in protecting the environment.
It is not surprising, then, that essentially all of the available field
measurement data base (a) dates from the late 1970s and early 1980s and
(b) primarily reflects western SCMs. Consequently, two limitations of available
data become immediately apparent:
1. Eastern surface coal mines may not be well characterized in terms
of emission characteristics. Recall that these mines tend to be
substantially smaller in terms of production and disturbed area. In
addition, there has long been a suspicion that open dust emission
levels differ substantially between the eastern and western United
States. This point is discussed further in the next section.
2. Throughout the country, available field measurements generally do
not reference the particle size range of current regulatory interest,
because of the relatively recent emergence of PM-10 as the basis
for the PM NAAQSs. Furthermore, some field measurements have
been found to be unreliable in terms of particle size
characterization. This, too, is discussed in Section 4.0.
Table 4 summarizes major field measurement studies undertaken to
determine emission factors generally applicable for SCMs.5"8 Note that only two
of the test programs considered mines east of the Mississippi River. The
PEDCo/MRI study forms the principal basis for EPA's recommended emission
factors for western surface coal. These factors are included in Section 8.24 of
the EPA publication "Compilation of Air Pollutant Emission Factors," commonly
referred to as "AP-42."9
Throughout the next section, it is assumed that the reader is familiar with
common open dust source measurement techniques such as "upwind/
downwind" and "exposure profiling." Detailed descriptions of open source
measurement methodologies are available elsewhere.10
. _ MRI-OTS\R9SOO-1031
1b
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Table 4. MAJOR FIELD TESTING PROGRAMS AT SURFACE COAL MINES
Name
Location (fields) Sources
Comments
Reference No.
EDS Study Powder River
PEDCo/MRI
Fort Union
Powder River
San Juan
Skelly & Loy
Logan County
West Virginia
Haul roads
coal dump
train loading
overburden
replacement
topsoil removal
wind erosion.
Coal loading
dozers
- overburden
- coal
dragline
haul roads
general traffic
scrapers
graders
D/OR/CL"
graders
haul roads
Emphasis on source depletion,
and "apparent emission factors'
at various downwind distances;
exposure profiling and upwind/
downwind approaches
Combination of exposure profiling
and upwind/downwind tests;
emission factors developed form
the backbone of AP-42
Section 8.24
Upwind/downwind sampling over
10-day period; screening-type
study.
PEDCo/
BuMines
Southern Illinois Haul roads
Southwestern
Wyoming
Northeastern
Wyoming
Exposure profiling with stacked
filtration units (SFUs); emphasis
on haul road dust control
efficiencies; no attempt made to
develop general emission factor
models.
8
Drilling, overburden replacement and coal loading treated as a single emission source.
17
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The EDS study was conducted to develop PM emission factors for
primary surface mining activities. Two mines in the Powder River Basin were
considered, with tests conducted between fall 1978 and summer 1979. Emission
factors are presented for the following sources:
trucks hauling coal or overburden (with and without watering as a control
measure)
coal dumping
train loading
overburden replacement
topsoil removal by scrapers
wind erosion of stripped overburden and reclaimed land
With the exception of haul trucks, emissions were characterized using an
upwind/downwind approach; haul truck tests employed exposure profiling.
Results are summarized in Table 5. TSP was the particle size range of interest.
This industry-sponsored program paid particular attention to particle
deposition and its implications for dispersion modeling. Emission factors are
presented not only for at-source conditions, and "apparent" factors are given for
distances of 500 and 1,000 m. At-source emission factors have largely been
incorporated into AP-42 Section 8.24.
The PEDCo/MRI study was conducted with the express goal of developing
emission factor equations for western SCM operations. TSP, IP, SP, and FP
were the size ranges of interest. Three mines—in the Fort Union, the Powder
River, and the San Juan Fields—were considered over the summer and fall of
1979 and the summer of 1980.
A combination of the exposure profiling, upwind/downwind, and portable
wind tunnel sampling methodologies were employed to characterize emissions
from the sources listed in Table 6, which summarizes the upwind/downwind and
exposure profiling tests emissions testing conducted. Wind tunnel
measurements and wind erosion emission factors are described later.
As noted earlier, this study provides most of the experimental basis for
AP-42 Section 8.24.
The Skellv & Lov study, conducted as one part of an EPA contract, is the
only field program in Table 4 devoted entirely to eastern surface coal mining.
MRI-OTS\R9800-103l
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Table 5. SUMMARY OF EDS5 RESULTS'
Source
Haul roads
Coal dump
Train load
Overburden replacement
Topsoil removal
Wind erosion
8 Taken from Reference
Emission factor at
source
22.0 Ib/VMT
0.066 Ib/ton
0.028 IbAon
0.012 IbAon
0.058 Ib/ton
0.38 ton/acre-year
@ 4.7 m/s mean
wind speed
1 1 . Size range is TSP.
Apparent
emission
factor at
500 m
8.5 Ib/VMT
0.024 Ib/ton
0.010 Ib/ton
0.004 Ib/ton
0.021 Ib/ton
not
applicable
Apparent
emission
factor at
1,000m
7.8 Ib/VMT
0.022 Ib/ton
0.009 Ib/ton
0.004 Ib/ton
0.01 9 Ib/ton
not
applicable
MRI-OTS\R9800-10 31
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Table 6. SUMMARY OF EMISSIONS TESTING CONDUCTED BY PEDCo/MRI
Location" Source
1 Coal loading0
2
3
1 Dozer overburden0
2
3
1 Dozer coal0
2
3
1 Draglinec
2
3
1 Haul roads0
1W
1 Haul trucks0
2
1W
3
1 Light-med. duty
vehicles
2
3
1 Scrapers
2
1W
3
2 Graders
3
Control
(C/U)b
U
U
C
U
U
C
U
C
U
U
U
U
U
U
U
U
No. of
tests
2
8
15
4
7
4
4
3
5
6
5
8
5
6
6
10
6
4
3
9
4
5
5
3
2
4
3
5
6
2
2
5
2
Range
0.004-0.031
0.002-0.121
0.005-1.271
0.600-22,2
0.000-19.8
2.500-25.9
8.300-50.8
1.000-13.4
152-670
0.001-0.446
0.000-0.071
0.021-0.246
1.100-18.4
4.500-47.8
12.90-33.0
0.600-8.2
3.900-8.2
0.600-3.4
0.710-73.1
1.800-24.1
6.300-24.1
1.800-8.4
0.350-0.82
5.500-8.2
0.35
0.600-0.93
7.800-9.0
3.900-50.2
10.30-74.3
163-355
4.0
1.800-7.3
8.600-34.0
Units Mean
Ib/ton 0.010
0.025
0.135
Ib/hr 8.0
2.97
10.4
Ib/hr 25.2
6.3
312
Ib/yd3 0.069
0.024
0.115
Ib/vmt 8.2
19.4
Ib/vmt 19.6
4.2
5.6
2.2
47.0
10.0
16.3
5.0
Ib/vmt 5.2
6.8
0.35
0.73
8.4
Ib/vmt 18.0
32.9
259
4.0
Ib/vmt 4.1
21.3
Size
TSP
TSP
TSP
TSP
TSP
1 = Fort Union
2 = Powder River Basin
3 = San Juan River Fields
W = Winter tests
C/U: controlled/uncontrolled.
Upwind/downwind tests.
20
MRI-OTS\R9800-1031
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Upwind/downwind field measurements were collected over a short, 10-day
period to determine TSP emission factors for
haul trucks
drilling/overburden removal/coal loading (considered as one source)
regrading of land where coal had been removed
See Table 7.
The scope and extent of this "screening type" study are much more
limited than those for the other programs listed in Table 4. In addition, the
authors noted that wind speeds and haul truck travel speeds were substantially
higher than in the western studies. Consequently, it is very difficult to interpret
the Skelly & Loy emission factors that are roughly an order of magnitude greater
than corresponding western results. At the very least, however, this study
indicates a need for further characterization of PM emissions at eastern SCMs.
The scope of thy PEDCo/BuMines study was much more focused than the
other studies in Table 4. While the othes programs considered several emission,
sources, this program was undertaken to determine the efficiency and cost-
effectiveness of dust controls applied to SC "'7 haul roads. Tests were conducted
at three mines—including one east of the Mio. :^sippi—during the summer and fall
of 1982. Types of controls considered included: salts, surfactants, adhesives,
bitumens, films, and plain water. Table 8 summarize i esults of this test
program.
Three points should be noted about this study. First, the report states
that, because of the emphasis on control efficiencies, there was no attempt made
to develop general emission facto--.? for unpaved haul roads.
Second, exposure profiling measurements were made using stacked
filtration units (SFUs). The SFUs were designed to produce data for the SP and
FP size fractions. However, an independent contractor has found that the SFU
collection media were selected on the basis of pore size and collection efficiency
was not verified through calibration. A 1985 collaborative study of five different
exposure profiling systems found that, as samples are collected, SFUs become
more efficient. As a consequence, concentration and emission factors are
systematically underestimated.12'13 Overall, the independent evaluation concluded
that SFUs could not be recommended for open dust emission characterization.12
As a result, this independent emissions data base is of little value in judging the
"predictive acou acy" of haul road emissions factors
Mfli-ors\RsS' o
-------
Table 7. SUMMARY OF EMISSIONS TESTING CONDUCTED
BY SKELLY & LOY7
Operation
Drilling/overburden
removal/coal loading
Regrading
Haul roads
Number of
samples
33
7
8
TSP
emission factor
339.6
442.2
54
246.8
Units
Ib/workday/acre
lb/workday/acrea
Ib/hr*
Ib/vehicle mile
Regrading emission factor stated in two sets of units for comparison
purposes.
22
MRI-OTS\R9800-1031
-------
Table 8. EMISSION FACTORS REPORTED BY THE
PEDCo/BuMINES STUDY
Location8
1
2
3
Control method
Calcium chloride
Acrylic
Petrotac
Lignon
Water
No control
Calcium chloride
Emulsified
asphalt
Acrylic
Lignon
Water
No contro!
Calcium ci iioride
Biocat
Arco
Lignon
No control
No. of
tests
6
12
2
8
12
20
18
16
12
20
12
39
8
3
4
8
<7
Emission factors5
Range
0.12-4.65
0.70-6.79
6.90-10.3
0.79-14.7
2.02-3.80
0.67-7.81
2.43-18.2
4.73-25.2
3.19-13.0
1.17-16.2
0.85-12.2
2.93-37.5
1.49-4.46
1 .44-7.79
1 .46-2.42
0.78-2.76
1.41-6.84
Mean
2.00
3.42
8.64
6.13
2.77
4.46
7.71
13.84
7.28
7.14
6.22
14.69
3.03
3.58
1.79
1.84
3.36
a 1 - Southern Illinois
2 - Southwestern Wyoming
3 = Northeastern Wyoming
1 TSP emission factors in units of Ib/vmt.
-------
Finally, much of the control efficiency data in the PEDCo/BuMines exhibit
anomalous behavior, such as showing increased efficiency over time. It is
believed that much of this is due to the fact that control efficiencies were not
referenced to dry, uncontrolled emissions. A 1987 update to Section 11.2 of
AP-42 demonstrated the regulatory importance of referencing unpaved road
efficiency to worst-case conditions.13
Besides studies specifically directed toward surface coal mines, other field
programs have produced emission factors that are applicable to a wide range of
sources at SCMs. Field tests have been conducted on public roads as well as in
various industries, including coal-fired power plants, iron and steel plants, stone
quarrying, mining, and smelting operations. The results of these tests have been
incorporated into "generic" emission factor models.
Section 11.2 of AP-42 presents generic open dust emission factors which
can be applied to the following SCM sources
• scraper travel
material handling activities for topsoil, overburden, and coal
haul roads for both overburden and coal
• loading and unloading of trucks
• loadout for transit
• general traffic
Note that generic emission factors are available for the four or five most
important emission sources identified earlier.
Finally, as part of a recently completed study for the State of Arizona, MRI
conducted a critical review of unpaved road emission estimation.14 The review
encompassed the PEDCo/MRI data.6 Pertinent results from this study are
discussed in the next section.
,, . MRI-OTS\R9800-1031
-------
SECTION 4
EMISSION FACTORS FOR USE AT SURFACE COAL MINES
The preceding section described common PM emission sources and past
field measurement efforts at SCMs. This section first describes EPA guidance on
emission estimation for SCMs and then presents a critical review of available
emission factors.
AP-42 EMISSION FACTORS AND PREDICTIVE EQUATIONS
EPA publication AP-42, "Compilation of Air Pollutant Emission Factors,"
represents official agency guidance on the emission factors to be used for a
wide variety of process, open, and mobile emission sources. Section 8.24 of
AP-42, entitled "Western Surface Coal Mining," presents numerous predictive
equations and single-valued emission factors for use at western SCMs.
Figures 7 and 8 reproduce AP-42 Tables 8.24-2 and 8.24-4, respectively.
The western SCM emission factor equations presented for TSP and IP in
Figure 7 are, almost without exception, the results from the PEDCo/MRI field
study (Tables 4 and 7). Changes since the section was originally prepared in
1983 have (a) revised the equation for blasting and (b) added PM-10 scaling
factors for use with the IP emission equations. Quality ratings are generally high,
with most equations rated "A" (excellent) or "B" (above average).15
The single-valued emission factors given in Figure 8 were developed from
the data of three field studies: PEDCo/MRI, EDS, and an early screening study
performed by PEDCo for EPA Region VIII. That screening study surveyed
12 operations at 5 different mines (denoted by Roman numerals in Table 8.24-4).
Although that report presented emission factors, it made no attempt to develop
generally applicable emission factors. Quality ratings for the single-valued
emission factors are generally low; most factors are rated between "C" (average)
and "E" (poor). For many of the sources, the reader is encouraged to use the
"generic" emission factors found in Section 11.2 of AP-42.
Taken together, Figures 7 and 8 represent official EPA guidance on
estimating particulate emissions at surface coal mines. Quality ratings are to be
decreased one letter grade (e.g., from B to C) if the factors are applied to an
eastern mine.9
MRl-OTS\R9800-1031 25
-------
CD
TABLE 8.24-2. EMISSION FACTOR EQUATIOMS FOR UNCONTROLLED OPEN DUST SOURCES AT
CO
00
Ocerat loir.
dlaat Inp
Truck li.jdir.;;
Bui Idozl ng
££
re
i Dragline
-W
£ Scraper
c.. (travel Model)
f. i
•j. Grading
g1 Vehicle traffic
£- (light/avdltai duty
»',' Haul truck
Artlva atorafe pile
(wind eroalon and
Maintenance)
par t Icul ata. TNT »
^TSP denotea what la
WESTERN SUR
Material Eailaalona by parti
VM> OC ux
Coal or
o»eibi.rdfn 0.0005A1-'
real (.16
(M)'-2
Coal 7».* (a)1-2
(M)1-3
Overburden 5.7 (a)1-2
(M)1-3
Overburden 0.0021 (d)1-'
(M)0-3
2.7 i 10-5 (,)l.3 (W)2-*
0.0*0 (S)2-5
5.79
(rO«-°
0.0067 (w)3-* (L)°-2
Coal 1.6 u
vehicle allr« traveled. NA - not available.
FACE COAI. MINES (ENGLISH UNITS)"
Jnlts Fsrcor
"•''•* ;;iO u=yd3 f
CM)0-3
t.2 i 1(T6 (a)1-* (W)2-5 -'.60 0.026 Ib/VMT *
0.051 (S)2-° 0.60 0.011 Ib/VMT ,
3.7? 0'.60 C.04- ib/VMT 3
.1 *. i
0.0051 («>•>••• 0.60 0-01/ ,b/VMT A
Ib Cf
HA NA (acrc)(hr)
•eaaured by • atandard high voluae aaBpler \*ff V-rion 11.2).
a - Material allt content ; ! • 5 • Bean vehicle
f° d - drop height
(ft) 1. • road aurface
•p#«d («ph)
allt loading (g/«2)
rop eg r
^Multiply the <15 \m equation bv thla fraction to determine eaJaatona.
'Multiply the TSF predictive equation by thle fraction to detarvlne eaileelona In the £2.
'Hating applicable to Mine Typea i. II and IV (,ee Tahlai 8.2*-5 and B.2*-6).
5 u* »lre range.
Figure 7. Copy of AP-42 Table 8.24-2, presenting emission factor equations for SCMs.
MR! OTSVR980O-10 31
-------
TABLE 8.24-4. UNCONTROLLED PARTICIPATE EMISSION FACTORS FOR
' OPEN DUST SOURCES AT WESTERN SURFACE COAL MINES
•ource
Drill im
Tep»oi3 ro»ova] by
acraper
Overburden
replacement
Iroc* loadiai by
power above 1
(batcb drop)c
Ira IB loadiBf (katcb
Material Mice
Xocatioc
Overburdca
Coal
Topseil
Overburden
Ovcrburdce
Coal
Any
V
AB)
IV
ABV
V
Aay
or CBBtiBuout drop)1
lotto* dixp truck
UBloadlBI
(katck drop)1
let tuff track
UBloadiBi
(batck drop'r
Scraper u&leadiBf.
(batcb drop)
ViBd croiioB of
expeeed areat
Koftan BuMcrali I
corrcapoadiBi oati
Overburden
Ual
Coal
Topaoil .
Wcded laad,
•tripped over-
burdct , |radec
overburdec
aaio& factor! vcrc
aod f.^t-S preaeBt characteristic!
correct uae of tk
(fro. Reicruce 5
«a* "BIBC Bpccific
III
V
iv •
IIJ
II
I
Any
V
IV
Aoy
developed
of e.ct of
" eo>iaaio&
e»ccpt let overburden drill]
. applied tc any veatern turtace coal
Total impended i
•1BC
articulate (ttf) deootri vBai
ISP
eauaeioa
«actork
1.3
C.5S
O.Z2
0.10
C.CJB
C.029
o.u
0.22
0.012
O.OMO
0.037
0.011
0.021
o.ou
0.0002
0.000)
0.002
0.00)
0.027
O.OH
0.005
0.002
0.020
0.0)0
O.Oli
0.0070
C.066
0.033
0.007
O.OOi
O.Ot
0.02
C.31
Ct«i
' 83 T
(kclercncr i)
tbe*c •!•<•
iactert The
Uftiti fatter
Ib/bolc ft
kg/bole B
H/bclr t
kt/bolr £
Ib/T I
k|/H| I
lb/7 fi
k,/B, B
Ib/T C
kt/B| - C
lb/I C
k(/fif C
lk/T B
k|/H| B
lb/I B
frf /ft* t)
Ib/T I
kj/T I
UA t
k|/B» I
lk/7 r
k|/H| t
lb/I I
k»/rl» I
lb/7 B
kt/H: B
Ib/T B
k,/»t B
lk/T I
kt/Hi I
Ib/T C
k|/H| C
T £
(acrc)tjr)
hi c
. Table* l.J*-l
let ten for
other loctora
LAS fro* ficfcrcocc 1) CAB be
L it Mcature^
by a *tudard ki|b
voluK ooo^icr (ooe oectioc 11.2).
Predictive •outuofi lactor o^uotlOBi. vbicb |eBer«lly provide otore *ccuratt
eilimjlei of UKIIOBI, ore BrcieBted it Ckiptti 11.
8.24-8
EMISSION FACTORS
9/88
Figure 8. Copy of AP-42 Table 8.24-4, presenting single-valued
emissions factor for SCMs.
MRI-OTS\R9800-10.31
27
-------
EVALUATION OF ALTERNATIVE EMISSION FACTORS
In this section, PM emission sources at SCMs are considered one by one,
in the same order as Table 3. Emission factors available for each source are
then discussed. Strengths and weaknesses of the factors emphasized, and
implications for future testing are also discussed.
The emission factors and predictive equations have been assigned
numbers for convenience; these are shown in Tables 9 and 10.
Topsoil Related Activities
Removal—The two emission factors identified for this operation
(numbers 2.a and 2.b in Table 10) are already included in AP-42. Both factors
have low quality ratings; in keeping with the general guidance given in
Section, 8.24, the value of 0.058 Ib/ton is preferred because of fewer restrictions
on its use.
All testing has been performed at western SCMs, and the applicability of
the factor to eastern mines has not yet been established. However, because
topsoi! removal tends to be a relatively minor operation in terms of PM
emissions—less than 1% of the total—it appears that further characterization of
this source is not as critical as for other sources.
Scraper travel—Recall that this was earlier identified as one of the four or
five most important emission sources at SCMs, The two emission factors
available for this source are:
• the scraper equation (numbers 5.a and 5.b in Table 9) developed
during the PEDCo/MRI study and included in Section 8.24
the genera! unpaved road emission factor (number 5,c in Table 9)
presented in Section 11.2.1 of AP-42
With the exception of an essentially linear dependence on silt content, the
models bear little resemblance to one another. In general, the AP-42 emission
factor mode! developed during the PEDCo/MRI study is recommended for use at
western surface coal mines.
Note, nowever, that over the past 15 years numerous investigators have
questioned the ability of unpaved road emission factors developed from tests in
the eastern United States to adequately predict emissions in the west. A recen
field study of unpaved roads in Arizona, however, found no evidence to supporf
contentions that western unpaved travel emissions are systematically
underpredicted.
MRI-OTS\R960j
28
-------
Table 9. SUMMARY OF EMISSION FACTOR EQUATIONS FOR SCMs
No.
1.a
1.b
2.a
2.b
2.c
2.d
3.a
3.b
3.C
3.d
3.e
4. a
4.b
4.c
5.a
5.b
5.c
6.a
6.b
6.c
7.a
7.b
7.c
7.d
7.e
Source Material"
Blasting C or O
C orO
Truck loading C
C
C or O
C
Bulldozing C
C
O
O
O
Dragline 0
0
O
Scrapers in
travel mode
Grading
General traffic
Equation/Factor"
961 AOB/D18M
0.0005 A1'5
1.16/M13
0.089/M09
k (0.0032) (U/5)1 3/(M/2)14
339.6
78.4 S1 2/M1 3
14s15/M14
5.7 s1 2/M1 3
0.75 S1 5/M1 4
54
0.0021 d11/M03
0.0016d°7/M03
k(0.0032)(U/5)13/(M/2)14
2.7x105s13W24
3.7 x 10"8 s14 W25
k(5.9)(s/12)(S/30)(W/3)07
0.040 S25
0.031 S20
54
5.79/M40
1.9/M43
k(5.9)(s/12)(S/30)(W/3)07
(w/4)C5(365-p)/365
4.83(S/45)150
1. 22(5/45) 18e
Particle
size
TSP
TSP
TSP
PM-10
e
TSP
TSP
PM-10
TSP
PM-10
TSP
TSP
PM-10
e
TSP
PM-10
f
TSP
PM-10
TSP
TSP
PM-10
f
TSP
PM-10
Units
Ib/blast
Ib/blast
Ib/ton
Ib/ton
Ib/ton
Ib/workday/acre
Ib/hr
Ib/hr
Ib/hr
Ib/hr
Ib/hr
Ib/yd3
Ib/yd3
Ib/ton
Ib/vmt
Ib/vmt
Ib/vmt
Ib/vmt
Ib/vmt
Ib/hr
Ib/vmt
Ib/vmt
Ib/vmt
Ib/vmt
Ib/vmt
Reference
PEDCo/MRI
AP-42 § 8.24C
PEDCo/MRI
AP-42 § 8.24d
AP-42 §11. 2.3
Skelly & Loy
PEDCo/MRI
AP-42 § 8.24d
PEDCo/MRI
AP-42 § 8.24d
Skelly & Loy
PEDCo/MRI
AP-42 § 8.24d
AP-42 §11. 2.3
PEDCo/MRI
AP-42 § 8.24d
AP-42 § 11.2.1
PEDCo/MRI
AP-42 § 8.24d
Skelly and Loy
PEDCo/MRI
AP-42 § 8.24d
AP-42 §11. 2.1
Reference 14
Reference 14
(continued)
ro
CO
-------
Table 9 (Continued)
oo
o
No. Source
8.a Haul trucks
8.b
3.C
a.c
Q.e
Material" Equation/Factor"
0.0067 W34LOZ
0.0031 V'36
246.8
k(5.9)(s/12)(S/30)(W/3)07
(w/4)os(365-p)/365
22.0
Particle
size
TSP
PM-10
TSP
f
TSP
Units
Ib/vmt
!b/vmi
!b/vmt
Ib/vmt
Ib/vmt
Reference
°EDCo/MRI
AP-42 § 8.24°
Skelly and Loy
AP-42 § 11.2.1
TRC/EDS
C-coal, O-overburden, T-topsoil.
Symbols used:
A = area blasted (ft7) W = mean vehicle weight (ton)
M = moisture content (%) S = mean vehicle speed (mph)
D = blasthole depth (ft) w = mean number of wheels
s = silt content (%) L = surface silt loading (g/m2)
U = mean wind speed (mph) p = mean annual number of days with at least 0.01 in. of precipitation
Factor based on a reexamination of PEDCo/MRI study results.
PM-10 factors based on IP emission factors developed »n P^DCo/MRI study.
For SP, k = 0.74; for PM-10. k = 0.35.
ror SP, k = 0.80; for PM-10 k = 0.36.
MRIOTS\R9800-1031
-------
Table 10. AVAILABLE SINGLE-VALUED EMISSION FACTORS
FOR SCM OPERATIONS
No.
1.a
1.b
2.a
2.b
3.a
4.a
5.a
5.b
6.a
6.b
6.c
6.d
6.e
6.f
6.g
7.a
8.a
Source
Drilling
Topsoil removal by scraper
Overburden replacement
Truck loading by power shovel
(batch drop)
Train loading (batch or
continuous)
Dump truck unloading (batch)
Scraper unloading (batch)
Wind erosion of exposed areas
Material8
O
C
T
T
0
O
C
C
0
C
C
C
C
C
C
T
S
TSD
emission
factor
1.3
0.22b
0.058
0.44b
0.012
0.037b
0.028
0.0002b
0.002b
0.027b
0.005b
0.020b
0.01 4b
0.066
0.007b
0.04b
0.38
Units
Ib/hole
Ib/hole
IbyT
Ib/T
Ib/T
Ib/T
IbAT
Ib/T
Ib/T
Ib/T
Ib/T
Ib/T
Ib/T
Ib/T
Ib/T
Ib/T
T/acre-year
a O—overburden; C—coal; T—topsoil; S-
graded overburden.
b Factor restricted to use at certain types
V in Figure 8).
seeded land, stripped overburden,
of mines (see Roman numerals I through
31
-------
In the case of scrapers, however, that question can be turned around to:
Do tests conducted at western SCMs tend to adequately predict emissions at
eastern mines? Although the applicability of the model to eastern mines has
never been empirically demonstrated, the AP-42 model is also generally
recommended for eastern mines,
in a larger sense, the AP-42 Section 8.24 emission factor models suffer
from a lack of independent test data against which model performance can be
assessed. In other words, all available test data were used to develop the
emission factor models. As a result, there are no data available to compare
measured emission factors against calculated values.
At a minimum, then, a limited field study of not only scraper but all other
travel-related emissions at eastern mines is needed to gauge the applicability of
the AP-42 emission factors. In the larger sense, however, the collection of
independent test data (at both eastern and western mines) is important to
assese model performance. The need for independent assessment grows as the
relative importance of the emission source increases. Consequently, the theme
of independent data will be repeated throughout this report for the four or five
most importani. sources identified earlier
Material handling, storage, and replacement activities—Only one emission
factor (number 7.a in Table 10) specifically addressing topsoil handling was
found. This factor dates from an early Region VIII screening study16 and is
restricted in AP-42 as applicable to SCMs similar to a lignite mine in North
Dakota However, Table 8.24-4 suggests that the generic material handling
predictive equation in Section i 1.2.3 (number 2.c or 4.c in Table 9) should result
in greater accuracy. The generic equation should also be more applicable to
eastern mines and is recommended for general use.
This source is a relatively minor contributor to PM emissions at SCMs and
the fseed for further study is less critical than for other sources.
Overburden Related Activities
Drilling- -In addition to the single-valued emission factors developed during
the PEDCo/MRI study (number 1.a in Table 10), the Skelly & Loy study presents
an emission factor for combined D/OR/CL—"drilling/overburden removal/coal
loading" (number ?.d in Table 9). Because the Skelly & Loy value is for
combined sources, the single-valued factor (number 1.a) for overburden drilling
is recommended. Again, this factor has not been shown to be applicable to
eastern mines Drilling emissions are relatively small contributions to total PM
emissions at surface mines, and further field study is not considered critically
important at ihe tune
MRI-OTS\R960G-
32
-------
Blasting—Only a TSP emission factor for blasting is available at this time.
This equation (number 1.b in Table 9) is the result of a 1987 reexamination of
certain sources in AP-42 Section 8.24 and replaced the earlier expression
(number 1.a in Table 9). The factor has not been shown to be applicable to
eastern mines. The contribution of blasting to total PM emissions at surface
mines is usually small, so use of a TSP factor to estimate PM-10 emissions
should not be overly restrictive. Furthermore, blasting presents formidable
logistical difficulties in sampling; consequently, further field study is not
recommended at this time.
Removal—For overburden removal without draglines, two emission factors
were identified (number 4.a in Table 10 and the combined D/OR/CL emission
factor from Skelly & Loy). The Skelly & Loy value is, of course, combined with
other sources and is based on removal by front-end loaders instead of power
shovels. AP-42 restricts the use of the 0.037 Ib/ton to specific mine locations.
Again, Table 8.24-4 of AP-42 suggests that the generic material handling
predictive equation in Section 11.2.3 (number 2.c in Table 9) should result in
greater accuracy. The generic equation should also be more applicable to
eastern mines, and is thus recommended for general use.
The AP-42 generic material handling equation was recently updated and
the need for further study is not believed to be critical at present.
For dragline mines, there are two potentially available emission factors
• the dragline equation (number 4.b in Table 9) developed during the
PEDCo/MRI and included in Section 8.24
• the general material handling emission factor (number 4.c in
Table 9) presented in Section 11.2.3 of AP-42
In general, the AP-42 dragline emission factor is recommended for both
western and eastern dragline mines. At a minimum, a limited field study is
needed to assess the applicability of the emission factor to eastern mines.
Because this can be one of the four or five most important PM sources at
dragline mines, there is a need for additional field tests (at both eastern and
western mines) to independently assess model performance.
Haul trucks—No fewer than four forms of emission factors (numbers 8.a
through 8.e in Table 9) were found for this source. The interest in this PM
source should not be particularly surprising because it is often one of the two
most important PM contributors at truck-shovel mines. The two single-valued
factors (8.c and 8.e) are not recommended for general use. Thus, the emission
factors considered potentially applicable to this source are:
MRIOTS\R9800-10 31 33
-------
» the haul truck equation (numbers 8.a and 8.b in Table 9) developed
during the PEDCO/MRI study and included in Section 8.24
• the general unpaved road emission factor (number 8.d in Table 9)
presented in Section 11.2.1 of AP-42
As was the case with scrapers, the two models bear little functional
resemblance to one another. The recent Arizona study found that the generic
unpaved road equation tends to overpredict haul truck emissions measured at
western SCMs.14 In general, then, the AP-42 Section 8.24 emission factor models
developed are recommended for use at both eastern and western surface coal
mines.
This recommendation is, however, provisional in that additional
independent data are critically needed. That is, while something is known about
the unpaved road equation, nothing is known about the performance of the
Section 8.24 model when applied either to eastern mines or to independent data
from western mines. (Because of problems noted earlier about sampler design,
the PEDCo/BuMines study results do not provide reliable data for model
validation purposes.) Because overburden and coal haul trucks can account for
up to half of the total PM emissions at surface coal mines, independent
quantitative assessment of the available models should be an important objective
of any future field effort.
At a minimum, then, field study of haul truck emissions at eastern mines
should be considered in future field efforts. In addition, collection of independent
test data (at both eastern and western mines) is important to provide a gauge of
model performance.
Material handling and storage activities—As with topsoil operations, the
generic material handling equation (number 2.c in Table 9) should be more
applicable to a broad range of SCMs and is recommended for general use. This
source is a relatively minor contributor to PM emissions at SCMh and the need
for further study is less critical than for other sources. Note, however, that
overburden tends to have moisture contents outside the range of the generic
equation. Some limited testing is suggested to determine the accuracy of the
equation in those applications.
Replacement—For truck-shove! operations, this can be a relatively
important PM emission source. Only one directly applicable factor (0.012 Ib/ton
number 3.a in Table 10) was found; this value represents TSP results from
western SCMs. in genera!, emissions from this source should be fairly accurately
estimated using the generic material handling equation, which is potentially
applicable to a wide range of mines and material characteristics. Because of
importance of this source at truck-shovel mines, further field characterization
study is strongly suggested.
MR)-OTS\R980G
34
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Dozer activities—Only the PEDCo/MRI study has tested emissions from
dozers at SCMs. The results were combined into the predictive emission
equation (numbers 3.a and 3.b in Table 9) presented in Section 8.24. Those
models are recommended for both western and eastern mines.
The dozer equations result in emission rates (i.e., Ib/hr) rather than
emission factors. The use of a rate has hindered application of the equation to
other types of particulate sources—most notably, landfills and remediation sites-
which may not share the same dozer operating patterns with SCMs.17
Because dozers can account for a reasonably important fraction
(approximately 1% to 3% each for overburden and coal) of emissions at SCMs,
some additional field study is recommended. At a minimum, the applicability of
the dozer equation to eastern mines should be addressed. It is recommended
that field results be expressed in terms of emission factors (instead of rates) to
facilitate transfer of the results to other emission sources.
Coal Activities
Drilling—Material presented earlier in connection with the drilling of
overburden is equally applicable here. The single-valued factor for coal drilling
(number 1.b in Table 10) is recommended. Although the factor has not been
shown to be applicable to eastern mines, drilling can be expected to be a
relatively small contributor to the total PM emission rate. Further field study is
not considered critically important at this time.
Blasting—Again, material presented earlier for overburden is equally
applicable here. The reexamined TSP equation (number 1 .b in Table 9) is
recommended. Because of logistical difficulties in sampler deployment, further
field study is not recommended at this time.
Coal loading—Two emission factors pertaining specifically to SCMs were
identified: the PEDCo/MRI equation presented in AP-42 and the Skelly & Loy
combined "D/OR/CL" factor. The Skelly & Loy value is based on a screening
study of several simultaneous sources; its general use is not recommended. In
addition, the generic materials handling equation is potentially applicable to this
source.
The similarity between the models numbered 2.a/2.b, and 2.c ends at their
functional dependence on moisture. There is no overlap in the moisture values
contained in the data bases supporting the two models; the generic factor is
based on tests of dry materials (approximately 0.25% to 5% moisture) while the
SCM data base has moisture contents ranging from 6.6% to 38%. Emission
factors calculated from the two models can easily differ by an order of magnitude
or more.
MRI-OTS\R9800-1031 35
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The difficulty in reliably estimating coal loading emissions should , ;ot be
particularly surprising because that source exhibited high variability during the
test program. The test report noted that coal loading data were more variable
than the other data and that uncertainty in predictions is proportionately greater.6
Over a total 25 tests at three mines, the relative standard deviation (or, coefficient
of variation) was 210%, or roughly twice that of any other source tested. At one
mine, the mean measured emission factor was an order of magnitude greater
than the mean at the other two mines.
The generic materials handling equation (number 2.c in Table 9) was
recently reexamined and was found to predict reasonably well TSP emissions
from a rotary coal car dumper at a power plant.13'18 That factor, on the other
hand, is not based on any field tests conducted at SCMs; its applicability to coal
loading at mines has not been demonstrated.
In general, it is recommended that an emission factor appropriate to a
coal loading operation be based on the moisture content of the coal being
loaded. For moisture contents greater than 5%, models labeled as 2.a/2.b in
Table 9 are recommended. For coals with lower moisture contents, the model
2.c in the table is suggested, The reader is cautioned that the appropriate input
value is surface moisture content, which can be determined by oven drying for
approximately 1.5 hr at 110°C. Longer drying times for coal can result in the loss
of bound moisture, yielding ar overestimated surfad noisture content.
Although coal loading tends to contribute only slightly to the total
emissions at SCMs, there is often confusion and/or debate as to appropriate
emission factors and input variables (:.o., surface versus bound moisture
contents). Furthermore, emissions have been found to vary widely between
mines-. Reexamination of this source is recommended for any future field
studies.
Truck haulage—The remarks about further study made in connection witr
overburden haul trucks are equally applicable here.
Truck unloading—Table 3.24-4 of AP-42 (see Figure 8) provides several
factors for coal truck unloading, depending upon the type of truck dump or upon
mine type (Roman numerals I through V). The table further suggests that the
generic material handling predictive equation in Section 11.2.3 (number 2.c in
Table 9) should result in greater accuracy. The generic equation should also be
more applicable to eastern mines and is recommended for general use. Recall
that the generic equation performed satisfactorily when applied to independent
coal car dumping test data. Truck unloading tends to be a minor contributor to
total mine emissions and further field study is not critically needed at this time.
However, collection of some field data with higher moisture contents is
recommended.
MRI-OTS',R£ ;'
36
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Material handling and storage activities—As with topsoil and overburden
operations, the generic material handling equation (number 2.c in Table 9)
should be more applicable to a broad range of SCMs and is recommended for
any intermediate handling operations. This source is a relatively minor
contributor to PM emissions at SCMs and the need for further study is less
critical than for other sources.
Dozer activity—Remarks made earlier concerning this source and the need
for further study are equally applicable here.
Loadout for train transit—Table 8.24-4 of AP-42 (see Figure 8) provides
two factors for train loading. In general, however, the generic material handling
predictive equation is recommended. Again, recall that the generic equation
(a) should be more applicable to eastern mines and (b) satisfactorily predicted
coal car dumping test results.
General Activities
General (medium/liaht-dutv) vehicle travel—Three emission factor
equations were identified as applicable for general vehicle travel:
the general vehicle expressions developed during PEDCo/MRI and
included in AP-42 Section 8.24 (numbers 7.a and 7.b in Table 9)
• the generic unpaved road emission factor included in AP-42 Section
11.2.1 (number 7.c in Table 9)
• recently developed models for light-duty (nominally 4 wheel, 35 to
55 mph, and 2 tons) vehicles on Arizona unpaved roads under dry
conditions (numbers 7.d and 7.e in Table 9)
Unlike other travel-related sources under consideration here, independent
emissions test data are available to examine the Section 8.24 model. When
applied to the independent data from Arizona and Colorado (with average
moisture contents around 0.2%), the Section 8.24 model overpredicted by two
orders of magnitude. This is at least partially the result of the narrow range of
moisture contents (0.9% to 1.7%) in Section 8.24 data base.
As part of the Arizona study, a review of historical data revealed no
evidence on the part of the Section 11.2.1 unpaved road model to systematically
underpredict emissions from western roads.
Because of the demonstrated weakness of the Section 8.24 model, the
following recommendations have been made for estimating emissions from
general traffic at SCMs:
MRI-OTS\R8800-1031 37
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1. The "Arizona models (nurnoers 7.d and 7.e in Table 9) are
recommended for light vehicles (less than 3 tons) traveling at least
35 mph on unpaved roads in arid portions of the western United
States.
2. For other situations, the generic unpaved road model (number 7.c
in Table 9) is recommended.
Because genera! traffic can account for a large portion of the total PM
emissions at a SCM, collection of additional field test data (at both eastern and
western mines) should be an important objective of any future field effort.
Roau grading—Two emission factors were found for this source: the
model from the PEDCo/MRI study included in Section 8.24 (numbers 6.a/6.b in
Table 9) and the single-valued factor of 54 Ib/hr from the Skelly & Loy program
(number 6.0 In Tabie 9). The general use of the Section 8.24 model is
recommended. Recall that these factors have not been shown to be applicable
to eastern mines.
In addition, the generic unpaved road equation from AP-42 Section 11.2.1
has been shown to conservatively overestimate the measured grading emission
factors. Because grading typically represents a minor contributor to total PM
emissions, the overestimation is probably -ot overly restrictive. Further field
study of grading emissions is not as critics ^s for other emission sources at
present. Any future testing of graders shouiu /"nphasize eastern mines.
Wind erosion '.open areas, storage piles)—Wind erosion of particulate hat".
been recently reexamined, and a new section of AP-42 (Section 11.2.7, Industrial
Aggregate Wind Erosion) prepared.9 Because substantially over half of
underlying data are from coal piles at SCMs, and at end-user locations, the need
for future field study «s not critical at this time. Any future testing should focus OP
eastern mines.
MRI-OTS\R9
3R
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SECTION 5
SUMMARY AND RECOMMENDATIONS
Table 11 summarizes the results from a review of available field
measurements from surface coal mines, and discusses suggested field testing.
For each anthropogenic emission source, an emission factor is suggested.
Overall, the recommendations follow the guidelines presented in
Section 8.24 of AP-42; the most notable exception is that for general light- to
medium-duty traffic. For this source, independent test data allowed an objective
evaluation and selection based on the performance of available emission models.
For the reader's convenience, recommendations are either shown in boldface or
are underlined.
Although a method has been recommended to estimate emissions for
each major PM source at SCMs, additional testing should be considered
necessary to address major shortcomings in the data base. The following
paragraphs present general conclusions and recommendations.
1. Although mines in the east account for half of the coal surface
mined in the United States, particulate emission sources at those
mines have not been well characterized. In general, eastern
surface coal mines are smaller but more numerous than mines west
of the Mississippi. Eastern mines have only begun to be
considered in terms of not only particulate emissions, but also
operating characteristics that affect emission levels.
There have long been suspicions that emission factors developed
from eastern tests underestimate emissions in the west. In the case
of SCMs, the question becomes turned around to: Can test results
from western SCMs tend to adequately predict emissions at eastern
mines? That is, how applicable are the AP-42 Section 8.24
emission factors to the eastern United States? At a minimum, then,
some eastern field verification of the AP-42 SCM emission factors is
necessary.
2. Applicability to eastern mines notwithstanding, it is unknown how
well most of the AP-42 SCM factors perform in a general sense.
Essentially all available test data were used in developing the
MRI-OTS\R8800-1031 39
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Table 11. SUMMARY OF RECOMMENDED EMISSION FACTORS AND FUTURE TESTING NEEDS
Source
Recommended emission
factor8
Topsoll—
Removal
Scraper travel
2.a in Tabie 10
5.a/5.b in Table 9
Material handling
2.c in Table 10
Overburden-
Drilling
1.a in Table 10
Comments and recommendations for further field testing1
Although the current need for further field testing is not critical,
any subsequent field activities should emphasize eastern mines.
The applicability of AP-42 emission factor models to eastern
mines needs to be investigated. Of greater importance,
independent test data (at both eastern and western mines) are
critically needed to assess model performance.
Generic AP-42 Section 11.2.3 emission factor model was recently
updated and is considered equally applicable to eastern and
western mines. Surface moisture contents of interest are largely
within range in data base underlying the generic emission factor.
The need for * Jrther study is not considered critical at this time.
Single valued factor has not been shown to be applicable to
eastern mines. Because drilling is a relatively small contributor to
overall emissions, further field study is not considered critically
important at present. Future testing activities should include
eastern mines.
(continued)
MPI-OTS\R980O-10 31
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Table 11 (Continued)
Source
Recommended emission
factor8
Comments and recommendations for further field testingb
Blasting
1 .b in Table 9
Removal
4.c in Table 9
4.a/4.b in Table 9
Recommended factor is the result of 1987 reexamination of
PEDCo/MRI data. Factor represents TSP only and has not been
shown applicable to eastern mines. Although only a TSP value
is available, its use is not believed to be overly conservative in
overall inventorying process. Field testing for this source poses
serious logistical challenges. Because blasting does not provide
a large contribution to total emissions, further testing is not
recommended at present.
Generic materials handling emission factor recommended for
truck-shovel mines. This model was revised in a recent update
to AP-42 Section 11.2 and is considered equally applicable to
eastern and western mines. In general, moisture contents of
interest are likely to be outside the range in the data base
underlying the generic factor. Limited study is recommended.
For dragline mines, the equation found in AP-42 Section 8.24 is
recommended. At a minimum, a limited field study is needed to
assess the applicability of the emission factor to eastern mines.
Additional field test data (at both eastern and western mines)
would permit independent assessment of model performance.
(continued)
MRI-OTS\R9800-tO 31
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ro
Table 11 (Continued)
Source
Recommended emission
factor8
Haul trucks
8.a/8.b in Table 9
Material handling
2.c in Table 10
Dozer activity
4.a/4.b in Table 9
Replacement
2.c in Tnnie 9
Comments and recommendations for further field testingb
Because overburden and coal haul trucks can account for up tc
half of the total PM emissions, it is important to have an
independent assessment of model performance. Thus, collection
of new field data at both eastern and western mines should be
an important objective of any future field effort.
Generic AP-42 Section 11.2.3 emission factor model was recently
updated and is considered equally applicable to eastern and
westeri mines. Moisture values are probably outside the range
of the underlying data base, however. Limited field testing
recommended, in conjunction with other overburden handling
operations
. a minimum, the applicability of the emission model to eastern
nines should be field verified. To facilitate the transfer of results,
T is recommended that results be expressed as emission factors
-dher than emission rates.
Because of the importance of this source at truck-shovel mines,
further field characterization (at both eastern and western mines)
study is strongly suggested.
(continued)
MRI OTS\R9800-10 31
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Table 11 (Continued)
Source
Recommended emission
factor8
Comments and recommendations for further field testing13
Coal-
Drilling
1.bin Table 10
Blasting
1 .b in Table 9
Coal loading
2.a/2.b or 2.c in Table 9
Single-valued factor has not been shown to be applicable to
eastern mines. Drilling is a relatively small contributor to overall
emissions. Further field study is not considered critically
important at this time. Future testing activities should include
eastern mines.
TSP factor resulted from 1987 reexamination of PEDCo/MRI data.
Has not been shown applicable to eastern mines. Although only
a TSP value is available, its use is not believed to be overly
conservative in overall inventorying process. Very difficult source
for field testing. Further testing not recommended at present.
Model 2.a/2.b recommended for surface moisture contents
greater than 5%, model 2.c recommended for surface moisture
contents less than 5%. Because of confusion and/or debate as
to appropriate emission factors and input variables (i.e., surface
versus bound moisture contents) and because of high variability
between mines, reexamination of this source is recommended in
future field studies. This testing could be combined with testing
of other handling activities (below).
(continued)
MRI-OTSVW800-10.31
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Table 11 (Continued)
Source
Recommended emission
factor
Comments and recommendations for further field testingb
Haul trucks
8.a/8.b !n Table 9
Unloading
2.c in Table 10
Material handling
Dozer activity
2.c in Table 10
4.a/4.b in Table 9
Because overburden and coal haul trucks can account for up to
half of the total PM emissions, it is important to have an
independent assessment of model performance. Thus collection
of new field data at both eastern and western mines should be
an important objective of any future fie'd effort.
Generic AP-42 Section 11.2.3 emission factor model was recently
updated and is considered equally applicable to eastern and
western mines. Moisture contents of interest for coal unloading,
however, tend to be far greater than those in generic data base.
Limited field testing effort, perhaps focused on eastern mines, is
recommended.
Same as previous comment.
At a minimum, the applicability of the emission model to eastern
mines should be field verified. To facilitate the transfer of results,
it is recommended that results be expressed as emission factors
Bather than emission rates.
(continued)
MRI-OTSVR9800-10 31
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Table 11 (Continued)
Source
Recommended emission
factor8
Comments and recommendations for further field testingb
Loadout for transit
General-
General traffic
2.c in Table 10
7.c or 7.d/7.e in Table 9
Road grading
6.a/6.b in Table 9
Same as comment for coal unloading.
Model 7.d/7.e recommended for light-duty, higher speed traffic in
arid portions of the western United States. Because general
traffic can account for a large portion of the total PM emissions
at a SCM, collection of additional field test data (at both eastern
and western mines) should be an important objective of any
future field effort. Note that, when applied to independent data,
the light- and medium-duty unpaved road emission model in
Section 8.24 overpredicted by one or two orders of magnitude.
Generic unpaved road equation will conservatively overestimate
the measured grading emission factors, and the overestimation
is probably not overly restrictive in developing a mine-wide PM
inventory. Further testing is not critical at present. Future testing
of graders should emphasize eastern mines.
8 Emission factors in bold differ from general guidelines given in Section 8.24 of AP-42.
b Suggested field testing underlined.
MRI-OTS\R9800-1031
Ol
-------
Section 8.24 factois. Thus, there are no independent data against
which calculated emission factors can be objectively compared.
The lack of independent test data represents a limitation on the use
of the SCM factors in both eastern and western mines.
The need for independent assessment grows as the relative
importance of the emission source increases. Consequently, the
theme of independent data is repeated throughout Table 1 1 for the
most important (in terms of contribution to total emission levels)
sources.
Because most SCM field measurements were made during the late
1970s and early 1980s, data generally reflect a particle size range
other than PM-10. The PM-10 emission factors presented in AP-42
Section 8.24 are actually scaled IP factors, with the scaling based
on size data presented for the generic emission factors presented
in Section 1 1 .2.
At a minimum, limited field verification of PM-10 emission factors at
eastern and western Sf^/ls should be considered necessary.
In keeping with the guida. •>.; ^.ovided in AP-42 Section 8.24, the
generic equation of Section 1 1 .? 3 has been recommended for
many of the materials handling .,; ,': "^tions. That equation has been
recently updated and has been fouriv. o satisfactorily predict TSP
emissions from coal dumping operations. Nevertheless, because
so many of material handling operations at SCMs involve materials
with surface moisture contents outside the range of the
Section 1 1 .2.3 factor, Table 1 1 suggests that additional field testing
be conducted.
MRl-OTS\R:-8' MO 3'
46
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SECTION 6
REFERENCES
1. U.S. Environmental Protection Agency, Non-Metallic Mineral Processing
Plants, Background Information for Proposed Standards.
2. Bureau of Mines, Minerals Yearbook (1986), Volume II.
3. Department of Commerce, Coal in the United States, Coal Exporters
Association, U.S. Department of Commerce, International Trade
Administration Office of Energy, March 1987.
4. Cole, C. F., B. L. Murphy, J. S. Evans, A. Garsd, Quantification of
Uncertainties in EPA's Fugitive Emissions and Modeling Methodologies at
Surface Coal Mines, TRC Environmental Consultants, February 1985.
5. Shearer, D. L, R. A. Dougherty, C. C. Easterbrook, Coal Mining Emission
Factor Development and Modeling Study, TRC Environmental Consultants,
July 1981.
6. U.S. Environmental Protection Agency, Improved Emission Factors for
Fugitive Dust from Western Surface Coal Mining Sources, EPA-600/7-84-
048, Two Volumes, March 1984.
7. Ettinger, W. S., and R. E. McClure, Fugitive Dust Generation on a
Southern West Virginia Surface Coal Mine, APCA Speciality Conference on
Fugitive Dust Issues in the Coal Use Cycle, April 1983.
8. Rosenbury, K. D., and R. A. Zimmer, Cost-Effectiveness of Dust Controls
Used on Unpaved Haul Ftoads, Two Volumes, Final Report for U.S.
Bureau of Mines, Minneapolis, Minnesota, December 1983.
9. U.S. Environmental Protection Agency, Compilation of Air Pollutant
Emission Factors (AP-42), Research Triangle Park, North Carolina,
September 1985.
10. Cowherd, C., Jr., and J. S. Kinsey (1986), Identification, Assessment, and
Control of Fugitive Paniculate Emissions, EPA-600/8-86-023, U.S.
Environmental Protection Agency, Washington, D.C.
MRI-OTS\R9BOO-1031
47
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1 1 , Jacko, R. B., Air Quality, in Surface Mining Environmental Monitoring and
Reclamation Handbook, Edited by L.V.A. Sendlein, H. Yazicigili, and C. L.
Carlson, Elsevier; New York,
12. Pyle, B. E., and J. D. McCain, Critical Review of Open Source Particulate
Emission Measurements: Part II— Field Comparison, Final Report.
Southern Research Institute, Project No. 5050-4, prepared for the U.S.
Environmental Protection Agency, February 1986.
13. Muleski, G. E., Update of Fugitive Dust Emission Factors in AP-42
Section 11.2, Report for U.S. Environmental Protection Agency, MRI
Project No. 8681 -L(1 9), July 1987.
14. Muleski, G. E., Unpaved Road Emission Impact, Report for Arizona
Department of Environmental Quality, March 1991.
15. U.S. 'environmental Protection Agency, Technical Procedures for
Developing AP-42 Emission Factors and Preparing AP-42 Sections, April
1980.
1b. U.S. bivironrnental Protection Agency, Survey of Fugitive Dust from Coal
Mines, EPA-908/1 -78-003, February 1978.
17. Mulesivi, G. E., Update of Fugitive Dust Emission Factors in AP-42, Report
for U.S. Environmental Protection Agency, MRI Project No. 8481-1(11),
August 1986
18 Brookman, E. T., D. H. Carnes, P. A. Catizone, K. J. Kelley, Determination
of Fugitive Coal Dust Emissions from Rotary Railcar Dumping, TRC
Environmental Consultants, May 1984.
48
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing!
REPORT NO
EPA-454/R95-007
3 RtCIPIENT'S ACCeSSION NO
TITLE AND SUBTITLE
Review of Surface Coal Mining Emission Factors
i. REPORT DATE
July 11,1991
6. PERFORMING ORGANIZATION CODE
AUTHOR(S)
8. PERFORMING ORGANIZATION REPORT NO.
PERFORMING ORGANIZATION NAME AND ADDRESS
Midwest Research Institute
Kansas City, Missouri
10. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
2. SPONSORING AGENCY NAME AND ADDRESS
Emission Factor and Inventory Group (MD-14)
Emission Monitoring and Analysis Division
Office of Air Quality Planning and Standards
U. S. Environmental Protection Agency, RTP, NC 27711
13. TYPE OF REPORT AND PERIOD COVERED
14. SPONSORING AGENCY CODE
15. SUPPLEMENTARY NOTES
16. ABSTRACT
This report was generated as a first step in reviewing emission factors for western
suraface coal mines in response to Section 234 of the Clean Air Act of 1990.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
c. COSATl Field/Group
18. DISTRIBUTION STATEMENT
19. SECURITY CLASS (Ttiis Report)
1. NO. OF
52
PAGES
20. SECURITY CLASS (This page I
22. PRICE
EPA Form 2220-1 (R»v. 4-77) PREVIOUS EDITION is OBSOLETE
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