United States
Environmental Protection
Agency
Industrial Environmental Research EPA-600/2-78-004y
Laboratory October 1978
Cincinnati OH 45268
Research and Development
Source Assessment
Transport of
Sand and Gravel
-------
EPA-600/2-78-004y
October 1978
SOURCE ASSESSMENT:
TRANSPORT OF SAND AND GRAVEL
by
J. C. Ochsner, P. K. Chalekode, and T. R. Blackwood
Monsanto Research Corporation
Dayton, Ohio 45407
Contract No. 68-02-1874
Project Officer
John F. Martin
Resource Extraction and Handling Division
Industrial Environmental Research Laboratory
Cincinnati, Ohio 45268
INDUSTRIAL ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
-------
DISCLAIMER
This report has been reviewed by the Industrial Environmental
Research Laboratory - Cincinnati, U.S. Environmental Protection
Agency, and approved for publication. Approval does not signify
that the contents necessarily reflect the views and policies of
the U.S. Environmental Protection Agency, nor does mention of
trade names or commercial products constitute endorsement or
recommendation for use.
11
-------
FOREWORD
When energy and material resources are extracted, processed, con-
verted, and used, the related pollutional impacts on our environ-
ment and even on our health often require that new and
increasingly more efficient pollution control methods be used.
The Industrial Environmental Research Laboratory - Cincinnati
(lERL-Ci) assists in developing and demonstrating new and
improved methodologies that will meet these needs both effi-
ciently and economically.
This report contains an assessment of air emissions from the
transport of sand and gravel. This study was conducted to pro-
vide sufficient information for EPA to ascertain the need for
developing control technology in this industry. Further informa-
tion on this subject may be obtained from the Extraction Techno-
logy Branch, Resource Extraction and Handling Division.
David G. Stephan
Director
Industrial Environmental Research Laboratory
Cincinnati
111
-------
PREFACE
The Industrial Environmental Research Laboratory (IERL) of the
U.S. Environmental Protection Agency (EPA) has the responsibility
for insuring that pollution control technology is available for
stationary sources to meet the requirements of the Clean Air Act,
the Federal Water Pollution Control Act, and solid waste legisla-
tion. If control technology is unavailable, inadequate, unecon-
omical, or socially unacceptable, then financial support is
provided for the development of the needed control techniques for
industrial and extractive process industries. Approaches con-
sidered include process modification, feedstock modifications,
add-on control devices, and complete process substitution. The
scale of the control technology programs ranges from bench- to
full-scale demonstration plants.
IERL has the responsibility for developing control technology for
a large number (>500) of operations in the chemical and related
industries. As in any technical program, the first step is to
identify the unsolved problems. Each of the industries is to be
examined in detail to determine if there is sufficient potential
environmental risk to justify the development of control techno-
logy by IERL. This report contains the data necessary to make
that decision for the air emissions from the transport of sand
and gravel.
Monsanto Research Corporation (MRC) has contracted with EPA to
investigate the environmental impact of various industries which
represent sources of pollution in accordance with EPA's responsi-
bility as outlined above. Dr. Robert C. Binning serves as MRC
Program Manager in this overall program entitled "Source Assess-
ment," which includes the investigation of sources in ea^h of
four categories: combustion, organic materials, inorganic mate-
rials, and open sources. Dr. Dale A. Denny of the Industrial
Processes Division at Research Triangle Park serves as EPA Pro-
ject Officer for this series. This study of the transport of
sand and gravel was initiated by lERL-Research Triangle Park in
August 1974; Mr. David K. Oestreich served as EPA Project
Leader. The project was transferred to the Resource Extraction
and Handling Division, lERL-Cincinnati, in October 1975; Mr.
John Martin served as EPA Project Leader through completion of
the study.
IV
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ABSTRACT
This report describes a study of air pollutants emitted by the
transport of sand and gravel on unpaved roads. The potential
environmental effect of the source was evaluated using a source
severity (defined as the ratio of the maximum time-averaged
ground level concentration to an ambient air quality standard or
an adjusted threshold limit value).
Sand and gravel production is the largest nonfuel mineral indus-
try in the U.S. Production of sand and gravel is associated with
needs of the construction industry, which consumes over 90% of
the output.
Trucks transport 92% of sand and gravel output. Air pollution is
created by movement of these vehicles over unpaved roads and by
wind erosion of the sand and gravel from truck beds. This report
focuses on emissions caused by vehicular movement on unpaved
roads because emissions due to wind erosion are shown to be
insignificant.
Of the ambient air quality criteria pollutants, only particulate
matter is emitted. The hazardous constituent of the emitted par-
ticulate is free silica. The average particulate emission factor
for the transport of sand and gravel is 0.49 g/vehicle-m, with an
average free silica content of 14% (by weight).
A representative sand and gravel plant processes 274 metric
tons/hr, with vehicular traffic of 22 vehicles/hr (allows for
round trips). The average length of the unpaved roads of the
plants is 2.2 km, and each truck carries an average load of
21 metric tons. The uncontrolled particulate emission factor for
the industry, due to vehicular movement, is 87 g/metric ton. The
source severities for particulate and free silica particulates
are 0.02 and 2.9, respectively.
Some plants have effectively used control measures such as
applying oil, or chemical solutions onto the road surface. Spot
measurements have shown that about 4% to 10% road moisture con-
tent reduces emissions by 99%. Future control techniques would
consider the emission influencing factors of vehicle speed,
vehicle size, number of wheels, tire width, particle size dis-
tribution, and road moisture content.
v
-------
Truck transport of sand and gravel is still expected to be the
dominant mode of transport in the future.
This report was submitted in partial fulfillment .of Contract
68-02-1874 by Monsanto Research Corporation under the sponsor-
ship of the U.S. Environmental Protection Agency. The study
covers the period August 1974 through February 1976, and the work
completed in September 1977.
VI
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CONTENTS
Foreword iii
Preface iv
Abstract v
Figures viii
Tables viii
Abbreviations and Symbols ix
Conversion Factors and Metric Prefixes xi
1. Introduction 1
2 . Summary 2
3. Source Description 5
Process Description 5
Source Composition 6
Emission Sources 7
Areas of Concentration and Population
Distribution 8
4. Emissions 10
Selected Pollutants 10
Pollutant Characteristics 10
5. Control Technology 16
State of the Art 16
Future Considerations 16
6. Growth and Nature of the Industry 19
Present Technology 19
Production Trends 19
References • 22
Appendices
A. Questionnaire Results 25
B. Emission Factor Estimation 28
C. Literature Survey 30
D. Source Severity Calculations 39
E. Free Silica Distribution 42
Glossary 48
Vll
-------
FIGURES
Number Page
Relationship of vehicular traffic to production
rate at a sand and gravel plant 7
Production of sand and gravel in the United
States 19
Comparison of trend projections and forecasts
for sand and gravel 21
TABLES
1 Sand and Gravel Method of Transportation in 1973. 6
2 Sand and Gravel Sold or Used by Producers in the
United States in 1972 by State and Class of
Operation 8
3 Representative Source Parameters 11
4 State and Nationwide Particulate Emissions Burden
due to Transport of Sand and Gravel 14
5 Contingency Forecasts of Demand for Sand and
Gravel by End Use, Year 2000 20
VTll
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ABBREVIATIONS AND SYMBOLS
ci / • • • cl o
b,...b2 -- constants
a', b', c1 — exponents expected to be in following range:
2.6
-------
t -- student's t
T -- vehicle weight
TLV -- threshold limit value
U -- wind speed
UA — relative wind speed
V -- vehicle speed
W -- tire width
X -- vehicular traffic
Xq -- distance at which the source severity of
p particulate matter equals 0.1
Xq -- distance at which the source severity of free
s silica particulate matter equals 0.1
y — production rate
y -- time-averaged maximum ground level concentration
irmax -- a constant, 3.14
p -- bulk density
a — overall standard deviation
x
-------
CONVERSION FACTORS AND METRIC PREFIXES3
CONVERSION FACTORS
To convert from
centimeter (cm)
gram (g)
kilogram (kg)
kilometer (km)
kilometer2 (km2)
meter (m)
meter (m)
meter2 (m2 )
meter2 (m2)
meter3 (m3)
meter3 (m3)
metric ton
to
inch
pound-mass (Ib mass
avoirdupois)
pound-mass (Ib mass
avoirdupois)
mile
mile2
foot
inch
foot2
inch2
foot3
inch3
ton (short, 2000 Ib mass)
Multiply by
0.394
2.204 x 10~3
2.204
0.622
3.860 x 10-1
3.281
3.937 x 101
1.076 x 101
1.550 x 103
3.531 x 103
5.907 x I0k
i 1.102
METRIC PREFIXES
1
Prefix Symbol
kilo k
milli m
micro y
nono n
Multiplication
factor
10 3 1 kg =
10~3 1 mm =
10 ~6 1 ym =
10~9 1 nm =
Example
1 x 10 3 grams
1 x 10~3 meter
1 x 10~6 gram
1 x 10~9 meter
^Metric Practice Guide. ASTM Designation E 380-74, American
Society for Testing and Materials, Philadelphia, Pennsylvania,
November 1974. 34 pp.
XI
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SECTION 1
INTRODUCTION
Transport of sand and gravel results in dust emissions due to
vehicular movement on unpaved roads. A literature and sampling
survey of these emissions was conducted to provide a better
understanding of the distribution and character of emissions than
has been previously available in the literature. When collecting
data, emphasis was focused on accumulating sufficient information
to permit EPA to decide on the need for control technology
development.
The following information is compiled in this document:
• a method to estimate emissions from transport of sand and
gravel
• composition of emissions
• hazard potential of emissions
• vehicular traffic around a sand and gravel plant
• trends in the transportation of sand and gravel and their
effects
• types of control technology used and proposed
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SECTION 2
SUMMARY
Sand and gravel production is the largest nonfuel mineral indus-
try in the U.S. Since the construction industry consumes more
than 90% of the sand and gravel output, sand and gravel produc-
tion is associated chiefly with the needs of this industry. In
1972, there were 5,384 sand and gravel plants engaged in active
production. A total of 1,008 million metric tons of sand and
gravel were sold or used by producers in 1972. California, with
129 million metric tons/yr, ranked first in sand and gravel out-
put, followed in order by Michigan, Ohio, Illinois, Minnesota,
Wisconsin, and Texas as the top seven producing states.
Trucks transport 92% of the vast quantity of sand and gravel,
resulting in a high degree of traffic activity within sand and
gravel sites. Air pollution is created by vehicular movement
over unpaved roads and by wind erosion of the sand and gravel
from truck beds; however, wind erosion emissions are shown to be
insignificant. This report focuses on the emissions caused by
vehicular movement on unpaved roads.
Of the ambient air quality criteria pollutants, only particulate
matter is emitted. The average particulate emission factor for
transport of sand and gravel on unpaved roads is 0.49 g/vehicle-m.
The hazardous constituent of the emitted particulate is free
silica. Prolonged exposure to free silica results in a pulmonary
fibrosis known as silicosis. The threshold limit value for free
silica is less than half the threshold limit value of inert
dusts. Free silica particulates therefore present a greater
health hazard than inert particulate matter. Particulate1 emis-
sions from the transport of sand and gravel contain from 1.4% to
47% (by weight) free silica, with an average of 14% (by weight).
This study characterizes the health hazard potential of uncon-
trolled emissions from all transport of sand and gravel sources.
This is accomplished by computing various evaluation criteria
for a defined representative source with average operating
parameters.
Production per sand and gravel plant can vary from <23,000 metric
tons/yr to highly automated plants capable of supplying 3.6 mil-
lion metric tons/yr. A representative sand and gravel plant pro-
cesses 274 metric tons/hr, with vehicular traffic of 22 vehicles/
2
-------
hr (allows for round trips). The average length of unpaved road
is 2.2 km and each truck carries an average load of 21 metric
tons. The uncontrolled particulate emission factor per metric
ton due to vehicular movement is 87 g/metric ton. The free
silica particulate emission factor is 12 g/metric ton.
To quantify the impact of this source on the environment, a
source severity (S) was defined. Source severity is the ratio of
the time-averaged ground level concentration (x~) at a representa-
tive downwind distance (D) to a criteria pollutant ambient air
quality standard or an adjusted threshold limit value. When the
ratio or severity is >1.0, the source is considered a definite
candidate for control technology development, while 0.1 < S < 1.0
indicates a possible need for additional control technology. The
severities for particulate matter treated as total suspened for
particulate and free silica containing particulate are 0.02 and
2.9, respectively.
Affected population is defined as the product of the land area
beyond the plant boundry, where severity is >0.1 or >1.0 and the
representative population density. No population is affected by
particulate matter severity. Free silica particulates affect a
population of 30,000 persons down to a severity of 0.1 and 1,650
persons to a severity of 1.0.
The state and national emission burdens are the ratio of mass
emissions of a criteria pollutant from the transport of sand and
gravel to the total mass emissions of that pollutant in each
state and in the nation, respectively. Twenty-one states each
have emission burdens for particulates >1.0%. The highest state
emissions burden is in Alaska, 9.8%. The national emission bur-
den for particulate is 0.49%.
The growth factor is defined as the ratio of mass emissions from
the transport of sand and gravel in 1977 to the 1972 emissions
level. The growth factor for particulates is 1.15.
Control of emissions from unpaved roads is not widely practiced
within the sand and gravel industry; however, some plants have
effectively used certain control measures. Both applying CaCl2
solutions, oil and lignin sulfonates and mixing stabilization
chemicals into the road surface have been practiced. Spot
measurements have shown that about 4% to 10% road moisture con-
tent reduces emissions by 99%. This would produce a controlled
particulate emission factor of 0.87 g/metric ton. Future control
techniques would involve consideration of the factors affecting
emissions. Emissions are primarily influenced by vehicle speed,
vehicle cross-sectional area and weight, number of wheels, tire
width, particle size distribution, and road moisture content.
Sand and gravel production is expected to grow at an average
annual rate of 3.9% to 4 .7%. By the year 2000, sand and gravel
production is expected to be 2,860 to 3,619 million metric tons/
-------
yr. Truck transport of sand and gravel is still expected to be
the dominant mode of transport in the year 2000.
-------
SECTION 3
SOURCE DESCRIPTION
PROCESS DESCRIPTION
The sand and gravel industry is the largest nonfuel mineral
industry in the U.S. A total of 1,008,075,000 metric tons3 of
sand and gravel were sold or used by producers in 1972 (1).
Government and contractor operations accounted for 14% of the
sand and gravel output while commercial operations produced 86%
(1). Government and contract operations are primarily involved
with large-scale projects such as highways and reclamation works.
Sand and gravel is primarily used in the construction industry,
which consumes over 90% of the output (2).
Because of the widespread occurrence of producing sand and gravel
near construction sites, 5,384 plants were engaged in commercial
production in 1972 (2). No single firm dominates the industry;
plant sizes vary from very small producers to highly automated
permanent installations. A survey of the sand and gravel
industry indicates that an average plant size is 6.4 x 105 met-
ric tons/yr (Appendix A).
Sand and gravel plants stockpile the finished products and
variously sized aggregates of sand in storage areas. The
finished products are transported to the consumer (primarily
construction industries) by means of truck, rail, or barge
systems. Truck haulage is the predominant form of transportation,
accounting for 92% of the transported sand and gravel. Trucks
used in hauling sand and gravel have an average capacity of 21
metric tons (Appendix A). The method of transporting sand and
gravel in 23 states is presented in Table 1 (personal communi-
cation with W~. Pajalich, U.S. Bureau of Mines, Division of Non-
metallic Minerals, Washington, D.C., November 7, 1974).
1 metric ton = 106 grams = 1.1 short tons; conversion factors
and metric prefixes are presented in the prefatory pages.
(1) Minerals Yearbook 1973, Volume I. U.S. Department of the
Interior, Bureau of Mines, Washington, D.C., 1975. p. 1105.
(2) Pajalich, W. Sand and Gravel. In: Minerals Yearbook 1973,
Volume I. U.S. Department of the Interior, Bureau of Mines,
Washington, B.C., 1975. pp. 1097-1115.
-------
TABLE 1. SAND AND GRAVEL METHOD OF TRANSPORTATION IN 1973
(103 metric tons)
State
California
Connecticut
Florida
Georgia
Idaho
Illinois
Iowa
Kansas
Louisiana
Missouri
Montana.
Nebraska
New Jersey
New York
North Carolina
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Virginia
Wisconsin
Wyoming
Truck
114,161
7,806
18,394
3,515
8,327
41,632
18,104
12,846
12,915
9,540
11,646
13,512
16,085
29,213
13,997
2,429
5,664
13,616
10,363
30,564
9,190
38,956
6,118
Railway
2,857
1,773
1,461
66
1,907
414
833
810
47
2,088
2,586
196
2,514
111
5,462
1,428
1,294
84
Waterway Other
1,608
380 149
306
870
2,521
Note.—Blanks indicate no reported data.
Partial list of states which transport.
SOURCE COMPOSITION
Sand and gravel are the natural products from the weathering of
rocks. The term "sand" is used to represent material within a
size range of 20 ym to 2,000 ym. Material in the size range bet-
ween 20 ym and 200 ym is termed as fine sand, and that between
200 ym and 2,000 ym is termed as coarse sand. The term "gravel"
is used to represent material larger than 2,000 ym. Silt is
material within a size range of 2 y to 20 ym, and clay is defined
as 0.1 ym to 2 ym particles (3).
(3) Stern, A. C. Air Pollution, Volume I-Air Pollution and Its
Effects. Academic Press, New York, New York, 1968. 50 pp.
-------
Sand and gravel consist primarily of silica. Other constituents
may be limestone or combined silica in the form of feldspar,
mica, and other mineral silicates and aluminosilicates (4).
EMISSION SOURCES
Dust emissions occur during truck transportation of sand and
gravel. Emission sources are divided into two categories:
1) vehicular movement on unpaved roads and 2) wind erosion from
the truck bed. However, based upon calculation, windblow emis-
sions are insignificant compared to unpaved road emissions
(Appendix B).
Emissions due to vehicular movement on unpaved roads are influ-
enced by vehicle speed, vehicle dimensions, number and width of
the wheels, particle size distribution and moisture content of
the unpaved road surface, and distance of the unpaved road from
the finished stockpile to the nearest paved highway. These fac-
tors are discussed in detail in Appendix C.
Vehicular traffic at a sand and gravel site varies with the pro-
duction rate of the facility. Figure 1, based on survey results
of the industry, illustrates this relationship. For a derivation
of this relationship, see Appendix A.
10 20 30
VEHICULAR TRAFFIC, vehicles/hr
Figure 1. Relationship of vehicular traffic to production
rate at a sand and gravel plant.
(4) Kirk-Othmer Encyclopedia of Chemical Technology, Second
Edition, Volume 12. John Wiley & Sons, Inc., "New York,
New York, 1967. 905 pp.
7
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AREAS OF CONCENTRATION AND POPULATION DISTRIBUTION
Geographically, the sand and gravel industry is concentrated in
large, rapidly expanding urban areas and on a transitory basis,
in areas where highways, dams, and other large-scale public and
private works are under construction. The distribution of sand
and gravel sold or used by producers in the U.S. is provided in
Table 2 (1). California ranks first in sand and gravel output
with 129 million metric tons in 1972, producing nearly twice as
much as second-ranked Michigan. The seven leading states in
descending order of production are California, Michigan, Ohio,
Illinois, Minnesota, Wisconsin and Texas. Combined production
from these seven states accounts for 40% of the U.S. sand and
gravel output.
TABLE 2. SAND AND GRAVEL SOLD OR USED BY PRODUCERS
IN THE UNITED STATES IN 1972 BY STATE
AND CLASS OF OPERATION (1)
(thousand metric ton and thousand dollars)
State
Alabama
Alaska
Arizona
California
Colorado
Connecticut
Delaware
Florida
Georgia
Hawaii
Idaho
Illinois
Indiana
Iowa
Kansas
Kentucky
Louisiana
Maine
Maryland
Michigan
Minnesota
Mississippi
Montana
Nebraska
New Hampshire
Ne Jersey
Ne York
No th Carolina
Oh o
Oregon
Pennsylvania
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Vermont
Virginia
Washington
west Virginia
Wisconsin
Wyoming
TOTAL
Populati
density
persons /ki
26
<1
6
14
49
8
241
107
48
31
46
3
77
56
20
11
31
31
12
153
281
60
19
18
26
2
7
2
32
368
3
147
40
3
100
14
6
101
350
33
3
37
16
5
18
45
20
26
31
1
22
an
Commercial
i2 Quantity
7 ,003
4,688
24 ,938
115^126
24,468
6,531
2,466
24,606
4,207
644
4,217
43,587
29,385
17,389
10,215
9,174
20,439
4,549
13,700
16,267
60,290
33,573
14,658
11,100
2,35
13,58
8 , 51
5,30
19,47
6,18
27,11
10,37
5,19
47 ,71
8,05
22,86
20,66
2,21
8,728
6,364
11,512
36,423
12 , 847
2,731
15,409
6,356
26,922
4,055
867 ,406
Value
8,530
4 ,183
29,131
15 , 045
154^544
30,285
9,560
2,660
16,963
4,729
1,890
5,896
61,328
32,348
19,064
9,588
11,919
26,255
26,517
23,782
63,646
29,972
15,867
14,779
13,376
10,691
5,951
38,010
6,894
36,321
12,400
4,678
59,702
10,181
30,462
36,804
3,265
12,121
6,423
15,157
54,658
13, 989
3,014
21,646
15,030
24,860
4,142
1,089,132
Government and
contractor
Quantity
b
10,955
2,451
1 732
14,189
6,732
925
b
50
b
28
4,268
438
1,462
1,472
2,565
180
422
184
2,552
5,275
6,991
137
15
1,547
2,601
1,327
14
2,195
2,346
3,763
2,176
252
656
4,138
b
76
b
7,691
439
2,332
3,271
910
120
c
13,244
5,975
140,669
Value
b
11,031
3,290
8^075
4,346
1,710
b
45
b
3
4,398
368
943
1,076
1,333
48
740
40
1,673
1,799
3,482
266
1,688
1,945
305
11
1,659
631
1,413
1,078
230
957
4,519
b
" 71
b
8,369
172
1,670
3,082
199
48
2,629
1
6,443
10,774
111,569
Total3
Quantity
7,003
15,642
27,369
129^314
31,222
7,456
2,488
24,656
4,207
671
8,465
44,023
30,847
16,861
12,779
9,355
20,860
13,865
2,619
65,565
40,565
14,795
15,127
11,115
6,637
19,492
8,379
29,462
14,138
7,366
47,967
8,711
27,000
20,680
2,292
8,728
14., 055
11,950
38,755
16,118
3,641
15,529
25,430
6,356
40,165
10,031
1,008,075
_ Value ___
6,530
15,214
32,420
162)619
34,631
11,270
2,660
17,009
4,729
1,893
10,294
61,696
33,290
20,140
10,920
11,967
26,996
7,535
26,557
25,655
65,445
33,454
16,133
15,063
12,636
6,256
38,020
8,553
36,952
13,812
5,757
59,932
11,138
34,981
36,804
3,336
12,121
14,793
15,328
56,328
17,071
3,214
21,696
26,069
15,031
31,324
14,916
1,200,701
3Data may not add to totals shown because of independent rounding.
None produced.
-------
Table 2 also lists the population density of each state. Using
the densities of the seven leading producing states, the average
population density of a sand and gravel producing area is defined
as 50 persons/km2.
-------
SECTION 4
EMISSIONS
SELECTED POLLUTANTS
Of the ambient air quality criteria pollutants, only particulate
matter is emitted. The main hazardous constituent of the parti-
culate emitted due to sand and gravel transportation is free
silica. Prolonged inhalation of dusts containing free silica
may result in a disabling pulmonary fibrosis known as silicosis.
The action of silica on the lungs results in the production of
a diffuse, nodular progressive fibrosis which may continue to
increase for several years after exposure is terminated. The
first and most common symptom of uncomplicated silicosis is dry
cough and shortness of breath upon exertion. As the disease
advances, the shortness of breath becomes worse and the cough
becomes more troublesome. Further progress of the disease
results in marked fatigue, loss of appetite, pleuritic pain, and
total incapacity to work. Extreme cases may eventually cause
death due to destruction of the lung tissues (5).
The American Conference of Governmental Industrial Hygienists
(ACGIH) has suggested a threshold limit value (TLV®) of 10/
(% Quartz + 2) mg/m3 for respirable dusts containing quartz or
free silica. Furthermore, particulate is one of the criteria
pollutants. Dusts with <1% silica are termed "inert," and a
TLV of 10 mg/m3 is suggested for these (6).
POLLUTANT CHARACTERISTICS
Mass Emissions
The average particulate emission factor for the transport of sand
and gravel is 0.49 g/vehicle-m (Appendix C). Given the average
production rate for a representative source (described below) of
(5) Sax, N. I. Dangerous Properties of Industrial Materials,
Fourth Edition. Van Nostrand Reinhold Company, New York,
New York, 1975. 1258 pp.
(6) TLVs® Threshold Limit Values for Chemical Substances and
Physical Agents in the Workroom Environment with Intended
Changes for 1975. American Conference of Government
Industrial Hygienists, Cincinnati, Ohio, 1975. 97 pp.
10
-------
274 metric tons/hr and the emission rate from Appendix D of
6.6 g/s, the emission factor per metric ton of sand and gravel
transported is 87 g/metric ton and per year is 56 metric ton/yr.
Composition of Emissions
The free silica content of the particulate matter ranges from
1.4% to 47% (by weight). The average free silica content is
14.1% + 4.6% at the 95% confidence level (Appendix E). The free
silica particulate emission factor is 12 g/metric ton.
Definition of the Representative Source
A representative sand and gravel plant is defined in order to
characterize emissions from the transport of these aggregates on
unpaved roads. The representative source is defined as one that
has the average emission parameters. These parameters were
obtained from a survey of the sand and gravel industry (Appendix
A) and are listed in Table 3.
TABLE 3. REPRESENTATIVE SOURCE PARAMETERS
Parameter
Production rate , metric tons/hr
Unpaved road distance, km
Truck capacity, metric tons
Vehicular traffic, vehicles/hr
Average
2749
2.2
21b
22
Standard
Deviation
±265
±2.7
±2.5
±21
aBased on 9 hr/day, 260 days/yr.
Based on 2 trips/load.
The Criteria for Air Emissions
The hazard potential of emissions from the representative source
are quantified through the following evaluation criteria: source
severity, affected population, emission burden, and growth fac-
tor. These criteria are defined and presented in the following
sections.
Source Severity—
Source severity, S, is defined as
S = f (1)
where x" is tne time-averaged ground level concentration of each
pollutant and F is defined as the primary amibent air quality
11
-------
standard for criteria pollutants (particulates, SOX/ NOX, CO and
hydrocarbons) . For noncriteria pollutants,
F E TLV • 8/24 • 0.01 (2)
The factor 8/24 adjusts the TLV® (threshold limit value) to a
continuous rather than workday exposure, and the factor 0.01
accounts for the fact that the general population is a higher
risk group than healthy workers. Thus, x"/F represents the ratio
of the time-averaged ground level concentration to the concentra-
tion constituting an incipient hazard potential.
Through a derivation presented in Reference 7, the source
severity for particulate matter, S , is expressed as
_ 4.020J3
P Dl . 814
where Q = emission rate, g/s
D = representative downwind distance, m
Distance, D, is the average length of unpaved road (2.2 km) which
is assumed to be equal to the downwind distance from the plant
boundary -
The source severity for particulates is computed as 0.02
(Appendix D) .
The source severity of free silica, S , is given by (7)
o
S =
s
D 1 . 8 1 4 . TLV
where TLV = threshold limit value
This source severity is computed to be 2.9 (Appendix D) .
Affected Population — „
Affected population is defined as the product of the land area
outside the plant boundary where severity is > 0.1 or > 1.0 and
the representative population density.
\1) Blackwood, T. R., and R. A. Wachter. Source Assessment:
Coal Storage Piles. Contract 68-02-1874, U.S. Environmental
Protection Agency, Research Triangle Park, North Carolina.
84 pp.
12
-------
This quantity is useful in characterizing emissions because
although a given source may exceed some criteria, it may have
only a small effect on human health if it is located in a
sparsely populated area. In addition, a source may have a large
value of S due to a small emission height. Again, its impact on
human health may be small because the low emission height
results in pollutants being dispersed over a very small area in
the immediate vicinity of the source.
Since the severity for particulates at the plant boundary of a
representative sand and gravel plant is < 0.1, the affected
population for S > 0.1 and 1.0 is zero. Free silica particulates,
however, affect a population of 30,000 persons for S > 0.1 and
1,650 persons for S ^ 1.0 (Appendix D). These numbers are based
upon the assumption that the population density around a repre-
sentative plant is 50 persons/km2, the average population den-
sity of the seven leading producing states.
State and National Emission Burden--
Emission burdens are ratios of mass emission of criteria pollu-
tants from a given source category (such as the transport of
sand and gravel) to total emissions of those pollutants in a
state or nationwide. Using the emission factor of 87 g/metric
ton and 1972 production data from Table 2, mass emission levels
from the transport of sand and gravel are computed and presented
in Table 4. These levels are compared with the 1972 National
Emissions Data Systems (NEDS) data base of mass emissions per
state, and the emission burdens are calculated.
Growth Factor—
The growth factor is determined from the ratio of known to pro-
jected emissions from a source type. For this report,
.,,-,. Projected Emissions in 1977 ,-.
Growth Factor = Emissions in 1972 (5)
Other 5-yr periods (e.g., 1975 and 1980) could also be used
depending on available data. The main purpose of this criterion
is to eliminate from consideration those sources whose emissions
are expected to decrease greatly in the near future due, for
example, to the implementation of new emission controls or to a
process being phased out of production.
Because the implementation of new controls is not expected to be
widespread, projected emissions for 1977 will be totally depend-
ent on production values. Production figures from Section 6 for
1972 and 1977 are 937 million metric tons and 1,080 million
metric tons, respectively. These numbers were determined from
a 20-yr production trend. Using the uncontrolled particulate
emission factor of 87 g/metric ton, the emissions are
13
-------
TABLE 4. STATE AND NATIONWIDE PARTICULATE EMISSIONS
BURDEN DUE TO TRANSPORT OF SAND AND GRAVEL
1972 Overall
particulate
emissions,
State metric tons/yr
Alabama
Alaska
Arizona
Arkansas
California
Colqr-ado
Coriftecticut
Delaware
Florida
Georgia
Hawaii
Idaho
Illinois
Indiana
Iowa
Kansas
Kentucky
Louisiana
Maine
Maryland
Massachusetts
Michigan
Minnesota
Mississippi
Missouri
Montana
Nebraska
Nevada
New Hampshire
New Jersey
New Mexico
New York
North Carolina
North Dakota
Ohio
Oklahoma
Oregon
Pennsylvania
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Vermont
Virginia
Washington
West Virginia
Wisconsin
Wyoming
U.S. TOTALS
610
1,360
2,380
1,110
11,250
2,720
650
220
2,150
370
60
740
3,830
2,680
1,640
1,110
610
1,810
1,130
1,210
1,810
5,700
3,530
1,290
970
970
1,320
970
580
1,700
730
2,560
1,230
640
4,170
760
2,350
1,800
200
760
1,220
1,040
3,370
1,400
320
1,350
2,210
550
3,490
870
87,700
Overall particu-
late emissions,3
metric tons/yr
1,178,643
13,913
72,685
137,817
1,006,452
201,166
40,074
36,808
226,460
4-04,574
61,621
55,499
1,143,027
748,405
216,493
348,351
546,214
380,551
49,155
494,921
96,160
705,921
266,230
168,355
202,435
272,688
95,338
94,040
14,920
151,768
102,785
160,044
481,017
78,978
1,766,056
93,595
169,449
1,810,598
13,073
198,767
52,336
409,704
549,399
71,692
14,587
477,494
161,934
213,715
411,558
75,427
17,872,000b
Contribution to
overall state
emissions, %
0.05
9.78
3.27
0.81
1.12
1.35
1.62
0.60
0.95
0.09
0.10
1.33
0.34
0.36
0.76
0.32
0.15
0.48
2.30
0.24
1.88
0.81
1.33
0.77
0.48
0.36
1.38
1.03
3.89
1.12
0.71
1.60
0.26
0.81
0.24
0.81
1.39
0.10
1.53
0.38
2.33
0.-25
0.61
1.95
2.19
0.28
1.36
0.26
0.85
1.15
0.49-
1972 National Emission Data System (NEDS) data base.
Total does not equal sum of states due to sources which are
considered to be uniformly distributed across the U.S.;
i.e., forest fires.
14
-------
1972: 87 g/metric ton x 937 x 106 metric ton/yr
= 8.15 x 1010 g/yr (6),
1977: 87 g/metric ton x 1,080 x 106 metric ton/yr
= 9.40 x 1010 g/yr (7)
The growth factor is
n A r\ _. 1 n I 0 ~ /,,—
= 1.15 (8)
9.40 x 1010 g/yr _
8.15 x 1010 g/yr
15
-------
SECTION 5
CONTROL TECHNOLOGY
STATE OF THE ART
Current air pollution control technology or methodology is not
widely practiced at sand and gravel transportation sources. Dust
generated from vehicular movement on unpaved roads and around
stockpiles is dependent upon the dryness of the area; hence, any
method used to add moisture to unpaved roads is helpful in con-
trolling dust levels. Natural phenomena such as rain or snow
inhibit dust emissions because the dust adhering to water is less
prone to emissions.
The prime source of dusts due to sand and gravel transportation
is travel over soil- or gravel-surfaced unpaved roads. Some sand
and gravel plants have employed several effective dust control
methods mainly involving the incorporation of an additive(s) to a
limited depth within the soil/gravel road surface.
FUTURE CONSIDERATIONS
Emissions due to the transport of sand and gravel on unpaved
roads are influenced by a number of factors, such as vehicle
speed, vehicle cross-sectional area and weight, number of wheels,
tire width, particle size distribution, and moisture content of
the unpaved road surface material.
Based on observations made during aggregate plant sampling, mois-
ture content and vehicle speed affect the emissions more than any
other of the above-listed factors. Moisture in the soil^helps in
binding the particles together and prevents them from becoming
airborne. Though detailed measurements were not taken to study
the influence of moisture content on emissions, spot measurements
show that about 4% to 10% of moisture content reduces emissions
by 99%.
The average vehicle speed of a haul truck on an unpaved road
ranges from 24 to 32 km/hr with a maximum of 48 km/hr. On a
thoroughly wet or oiled unpaved road, vehicle speed (<48 km/hr)
does not seem to have an effect on emissions. However, on a dry
unpaved road, higher vehicle speeds produce increased emissions.
16
-------
Additives such as calcium chloride can be used to reduce the sur-
face tension of water so that the dust can be wetted with less
water. Calcium chloride can be applied at a cost of ^$0.15/m2-yr
(8). The principal problems here are corrosion of vehicle bodies
and leaching by rain water or melting snow. More frequent appli-
cations may be necessary during summer months.
Another effective dust control method is to mix stabilization
chemicals into the road surface to a depth of from 2 cm to 5 cm
(9). A cement company uses a special emulsion agent called
Coheren, supplied by Golden Bears Division of Witco Chemicals
Company. The treatment involves spraying a solution of 4 parts
of water and 1 part of Coheren at the rate of 5 x 10~3 m3/m2
of the road surface. Certain pretreatment measures, such as
working the road surface into a stiff mud, are necessary to
prevent the Coheren binder from sticking to the vehicles. Peri-
odic maintenance such as a 1:7 Coheren/water solution spray keeps
the Coheren binder active. The dust control program as described
is found to give 3 yr of service at a total cost of $0.12/m2.
Some counties in Iowa have tried mixing cut-back asphalt into the
road surface to a depth of from 5 cm to 8 cm (10). This type of
surface treatment reduces dust emissions but requires periodic
maintenance, such as patching potholes.
Treating the road surface with oil once a month is another
efficient method of controlling unpaved road dust emissions. The
estimated cost of such applications is $0.10/m2-treated yr (11).
However, it has been shown that 70% to 75% of oil applied moves
from the surface of the road by dust transport and runoff. This
may result in ecological harm caused by the oil or its heavy
(8) Vandegrift, A. E., L. J. Shannon, E. W. Lawless,
P. G. Gorman, E. E. Bailee, and M. Reichel. Particulate
Pollutant System Study, Volume Ill—Handbook of Emission
Properties. EPA-22-69-104, U.S. Environmental Protection
Agency, Durham, North Carolina, May 1971. 629 pp.
(9) Significant Operating Benefits Reported from Cement Quarry
Dust Control Programs. Pit and Quarry, 63(7) :116, 1971.
(10) Hoover, J. M. Surface Improvement and Dust Palliation of
Unpaved Secondary Roads and Streets. Project 856-S,
Engineering Research Institute, Iowa City, Iowa, July 1973,
97 pp.
(11) Mineral Industry Surveys—1, 2. U.S. Department of the
Interior, Bureau of Mines, Washington, D.C., 1972. 12 pp.
17
-------
metal constituents (12). Furthermore, surface oiling requires
regular maintenance because roads treated in this way develop
potholes.
Lignin sulfonates, byproducts from paper manufacture, are also
used to control dust emissions. One of the commercially avail-
able lignin sulfonates, Orzan A, a product of Crown Zellerbach
Corporation, was tested on a farm access road in Arizona State
University (13). The method proved quite successful over 5 yr
of service, effectively suppressing dust at a cost of $0.47/m2
($0.10/yr).
Paving the road surface is the best method to control dusts, but
it is impractical due to its high cost and the temporary nature
of sand and gravel plants.
Emissions due to wind erosion of sand and gravel can be easily
controlled by water application. However, sand and gravel
plants do not employ specific control methods since emissions
from wind erosion of sand and gravel in the truck are minor and
do not pose a health problem. All states have some sort of
tarpaulin law, the implementation of which reduces emissions by
wind erosion from the truck bed.
The literature surveyed revealed that dust emissions due to sand
and gravel transportation can be reasonably controlled by methods
currently available. These methods require an appreciable
managerial dedication and expertise and the necessary monetary
investment to purchase, install, and maintain such systems.
(12) Freestone, F. J. Runoff of Oils from Rural Roads Treated
to Suppress Dust. EPA-R2-72-054, U.S. Environmental Pro-
tection Agency, Cincinnati, Ohio, October 1972. 29 pp.
(13) Bub, R. E. Air Pollution Alleviation by Suppression of Road
Dust. M.S.E. Thesis, Arizona State University, Flagstaff,
Arizona, 1968. 45 pp.
18
-------
SECTION 6
GROWTH AND NATURE OF THE INDUSTRY
PRESENT TECHNOLOGY
Present technological improvements include larger operating units,
more efficient portable and semiportable plants, new prospecting
methods utilizing aerial and geophysical surveying, and greater
awareness, of pollution control and land reclamation. Automatic
controls which were installed in many of the larger and newer
operations resulted in recovery of salable fractions even from
low-quality deposits. As urban deposits of sand and gravel
become depleted, the present trend is towards investigating local
bodies of water for new deposits.
PRODUCTION TRENDS
Sand and gravel production is very closely tied to activity in
the consuming industries. Sand and gravel production is associ-
ated chiefly with the needs of the construction industry since it
consumes more than 90% of the sand and gravel output. Figure 2
999
908
817
726
635
545
454
363
272
182
91
1950
1955
1960 1965
yr
1970
1975
Figure 2. Production of sand and gravel
in the United States (14).
19
-------
shows the yearly production of sand and gravel from 1950 to 1972
(14). The average annual growth rate for domestic production
between 1950 and 1965 was about 5.5%. This high rate was mainly
due to the large-scale highway construction program. Production
has leveled off since 1965 mainly due to a decreased activity in
the highway construction program.
Contingency forecasts by end use of sand and gravel demands in
the year 2000 are given in Table 5 and Figure 3 (15). The fore-
cast range was determined by assuming both positive and negative
effects from various contingencies, such as technological shifts
affecting the end use pattern, restrictions caused by land use
conflicts and environmental controls, availability of public
funds for construction, and competition from alternate materials
such as crushed stone used in asphalt paving. The final demand
range forecast for the year 2000 is 2,860 to 3,619 million metric
tons, corresponding to an average annual growth rate of 3.9% to
4.7%.
TABLE 5. CONTINGENCY FORECASTS OF DEMAND FOR SAND
AND GRAVEL BY END USE, YEAR 2000 (15)
(106 metric tons)
End use
U.S. Demand
in yr 2000
Low
High
Highway and street
construction
Other heavy construction,
general building
contractors
Excavation and foundation
work
Concrete construction
materials
Molding and foundry sands
Glass
Other uses
TOTAL
Adjusted range
1,524
774
241
66
16
22
27
2,670
2,860
2,032
1,092
454
93
33
50
56
3,810
3,619
(Mean 3,239)
(14) Minerals Yearbook 1973, Volume I. U.S. Department of the
Interior, Bureau of Mines, Washington, D.C., 1975. p. 1099
(15) Minerals, Facts and Problems. U.S. Department of the Int-
erior, Bureau of Mines, Washington, D.C., 1970. p. 1193.
20
-------
The 20-yr and 5-yr straight-line trend projections, also shown
in Figure 3, are much lower than the demand estimates based on
contingency forecasting methods, primarily due to the use of
exponentially -controlled growth factors.
Transportation costs constitute a major part of the delivered cost
of sand and gravel; in many cases, these costs may exceed the
sales value of the material at the processing plant. Hence, sand
and gravel plants are located near the point of use. However,
local zoning and environmental regulations and also depletion of
urban deposits may necessitate locating future sand and gravel
plants away from the point of use, thereby increasing the share
of rail and barge systems in sand and gravel transportation in
order to hold down transportation costs. Truck haulage will
still remain important, especially for local delivery of sand
and gravel, even if rail and water transportation are used for
long hauls to central distribution points. Ultimately, truck
transporation will finally increase the delivered price of sand
and gravel and thus may result in using cheaper substitute mat-
erials, such as crushed stone and other manufactured aggregates.
2,724
1,816
-2 908
FORECAST RANGE
LAST 20-YR TREND ,
DEMAND
LAST 5-YR TREND
-3,242
2,861
1,718
1,153
1949
1968
2000
P 3,632
2,724
1,816
908
CONSTANT RATIO •"
LAST 20-YR TREND^-""""
^^
" LAST 5-YR TREND
3,631
.3,250
2,869
1,734
1,135
1949
1968
2000
Figure 3. Comparison of trend projections and
forecasts for sand and gravel (15).
21
-------
REFERENCES
1. Minerals Yearbook 1973, Volume I. U.S. Department of the
Interior,- Bureau of Mines, Washington, D.C., 1975. p. 1105.
2. Pajalich, W. Sand and Gravel. In: Minerals Yearbook 1973,
Volume I. U.S. Department of the Interior, Bureau of Mines,
Washington, D.C., 1975. pp. 1097-1115.
3. Stern, A. C. Air Pollution, Volume I-Air Pollution and Its
Effects. Academic Press, New York, New York, 1968. 50 pp.
4. Kirk-Othmer Encyclopedia of Chemical Technology, Second
Edition, Volume 12. John Wiley & Sons, Inc., New York,
New York, 1967. 905 pp.
5. Sax, N. I. Dangerous Properties of Industrial Materials,
Fourth Edition. Van Nostrand Reinhold Company, New York,
New York, 1975. 1258 pp.
6. TLVs® Threshold Limit Values for Chemical Substances and
Physical Agents in the Workroom Environment with Intended
Changes for 1975. American Conference of Government
Industrial Hygienists, Cincinnati, Ohio, 1975. 97 pp.
7. Blackwood, T. R., and R. A. Wachter. Source Assessment:
Coal Storage Piles. Contract 68-02-1874, U.S. Environmental
Protection Agency, Research Triangle Park, North Carolina.
84 pp.
8. Vandegrift, A. E., L. J. Shannon, E. W. Lawless,
P. G. Gorman, E. E. Sallee, and M. Reichel. Participate
Pollutant System Study, Volume III--Handbook of Emission
Properties. EPA-22-69-104, U.S. Environmental Protection
Agency, Durham, North Carolina, May 1971. 629 pp.
9. Significant Operating Benefits Reported from Cement Quarry
Dust Control Programs. Pit and Quarry, 63(7):116, 1971.
10. Hoover, J. M. Surface Improvement and Dust Palliation of
Unpaved Secondary Roads and Streets. Project 856-S,
Engineering Research Institute, Iowa City, Iowa, July 1973.
97 pp.
22
-------
11. Mineral Industry Surveys—1, 2. U.S. Department of the
Interior, Bureau of Mines, Washington, D.C., 1972. 12 pp.
12. Freestone, F. J. Runoff of Oils from Rural Roads Treated
to Suppress Dust. EPA-R2-72-054, U.S. Environmental Pro-
tection Agency, Cincinnati, Ohio, October 1972. 29 pp.
13. Bub, R. E. Air Pollution Alleviation by Suppression of Road
Dust. M.S.E. Thesis, Arizona State University, Flagstaff,
Arizona, 1968. 45 pp.
14. Minerals Yearbook 1973, Volume I. U.S. Department of the
Interior, Bureau of Mines, Washington, D.C., 1975. p. 1099-
15. Minerals, Facts and Problems. U.S. Department of the Int-
erior, Bueau of Mines, Washington, D.C., 1970- p. 1193.
16. Anderson, C. Air Pollution from Dusty Roads. In: Proceed-
ings of the 1971 Highway Engineering Conference, (Bulletin
No. 44-NMSU-EES-44-71, Las Cruces, New Mexico, 1971. 12 pp.
17. Investigation of Fugitive Dust Sources, Emissions, and Con-
trol. Contract 68-02-0044, U.S. Environmental Protection
Agency, Research Triangle Park, North Carolina, May 1973.
152 pp.
18. Roberts, J. W., A. T. Rossano, P. T. Bosserman,
G. C. Hofer, and H. A. Watters. The Measurement, Cost and
Control of Traffic, Dust and Gravel Roads in Seattle's
Duwamich Valley. In: Proceedings of the Annual Meeting of
the Pacific Northwest International Section of the Air
Pollution Control Association, Paper No. AP-72-5, Eugene,
Oregon, 1972. 10 pp.
19. Cowherd, C., Jr., K. Axetell, Jr., C. Guenther, F. Bennett,
and G. Jutze. Development of Emission Factors for Fugitive
Dust Sources. EPA-450/3-74-037, U.S. Environmental Pro-
tection Agency, Research Triangle Park, North Carolina,
June 1974. 172.pp.
20. Chepil, W. S. Dynamics of Wind Erosion: I. Nature of the
Movement of Soil by Wind. Soil Science, 60 (4): 305-320 , 1945.
21. Chepil, W. S., W. H. Siddoway, and D. V. Armburst. Climatic
Factor for Estimating Wind Erodability of Farm Fields.
Journal of Soil and Water Conservation, 17:162-165, 1962.
22. Thornthwaite, T. W. Climates of North America According to
a New Classification. Geographic Review, 21:633-655. 1931.
23
-------
23. Woodruff, N. P., and F. H. Siddoway. A Wind Erosion
Equation. Soil Science Society of American Proceedings,
29 (5) :602-608, 1965.
24. Chepil, W. S. The Transport Capacity of the Wind. Soil
Science, 60 (4) :475-480 , 1945.
25. Singer, J. M., E. B. Cook, and J. Grumer. Dispersal of Coal
and Rock Dust Deposits. Report of Investigations No. 7642,
U.S. Department of the Interior, Bureau of Mines, Washing-
ton, D.C., 1972. 32 pp.
26. Cares, J. W., A. S. Goldin, J. J. Lynch, and W. A. Burgess.
The Determination of Quartz in Airborne Respirable Granite
Dust by Infrared Spectrophotometry. American Industrial
Hygiene Association Journal, 34 (7) :298-305, July 1973.
24
-------
APPENDIX A
QUESTIONNAIRE RESULTS
The results of completed questionnaires (shown in Figure A-l)
received from 19 sand and gravel plants are shown in Table A-l.
Name and Address of Company_
Person Preparing this Questionnaire
Phone Number
Numberi
1
2
3
Plant Location
County and State
Production
Rate Short
Tons/Year2
Percent
Transported
By Truck
Frequency of
Truck Trans-
port3
Number and
Hauling Ca-
pacity of
Trucks
Type of Unpaved
RrwHs4
Gravel
Soil
Other
(Specify)
Approximate
Distance of
Unpaved Road1*
Average
Distance of
Truck Haulage
Please furnish the required information for plants with (l)minimum, (2)average and (3)maximum capacities.
This data will be treated as confidential.
3
Hours per day the transport operation lasts.
4
Unpaved road from finished stockpiles to the nearest paved highway.
5Average distance of truck haulage from finished stockpile to the user.
Figure A-l. Survey Questionnaire.
The average size of sand and gravel plants is 6.4 x 105 metric
tons/yr. Plants operate for ^9 hr/day, 260 days/yr throughout
the year. The trucks in use have an average capacity of 21 met-
ric tons.
Unpaved road length has no relationship to production rate and
vehicular traffic. Various correlations, such as nonlinear and
multiple linear regressions, were instigated but these did not
provide any significant results. The mean distance of unpaved
road is 2.2 kilometers.
aNonmetric units shown in this appendix correspond to those used
on the questionnaire.
25
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TABLE A-l. QUESTIONNAIRE RESULTS
Production rate
Response
number
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
10 metric
tons
9.10
0.90
1.80
0.90
9.10
4.10
3.60
3.60
13.60
0.90
0.90
9.10
9.10
2.30
4.50
9.10
2.60
10.40
26.10
tons/yr
10.00
1.00
2.00
1.00
10.00
4.50
4.00
4.00
15.00
1.00
1.00
10.00
10.00
2.50
5.00
10.00
2.86
11.50
28.80
Distance of
unpaved roads
kilo-
meters
0.80
0.40
1.61
1.61
1.61
1.61
3.22
8.05
8.05
1.61
8.05
0.80
0.53
1.21
0.80
0.40
0.40
0.16
0.19
miles
0.50
0.25
1.00
1.00
1.00
1.00
2.00
5.00
5.00
1.00
5.00
0.50
0.33
0.75
0.50
0.25
0.25
0.10
0.12
Average truck
capacity
metric
tons
20.4
15.9
22.7
22.7
22.7
22.7
22.7
22.7
22.7
22.7
22.7
18.1
15.2
22.7
19.1
22.7
22.7
22.7
22.7
Vehicular
traffic,
tons vehicles/hr
22.5
17.5
25.0
25.0
25.0
25.0
25.0
25.0
25.0
25.0
25.0
20.0
16.7
25.0
21.0
25.0
25.0
25.0
25.0
15.0
2.0
3.4
1.7
17.0
5.8
6.8
6.8
15.3
1.7
1.7
21.4
25.6
3.9
9.3
7.8
5.5
22.2
41.5
AVERAGE
6.40
7.00
2.20
1.30
23.6
11.3
With the paired values of vehicular traffic and annual production
rate (x, y), an investigation was made into what mathematical
formula best describes the relationship between the variables.
An effort was made to fit the data to three curve types: linear,
logarithmic, and exponential. The results are as follows:
Linear
Logarithmic
y
al
an
y
a2
= a:x + a0
= 54,445
= 26,154
= 0. 86
= a2 + b^
= -394,395
= 519,494
= 0.70
(A-l)
(A-2)
26
-------
Exponential
y =
r2 =
box
a3e 2
158,643
0.08
0.72
(A-3!
The quantities a0, alf a2 , a3, bj and b2 are constants. A third
value was also found for each type, the coefficient of determina-
tion, r2- The value of r2 lies between 0 and 1 and indicates how
closely the equation fits the experimental data. The closer r2
is to 1, the better the fit; therefore, a linear relationship is
the best fit. The resultant equation may be expressed as
follows:
y = 54,445x + 26,154
(A-4
27
-------
APPENDIX B
EMISSION FACTOR ESTIMATION
EMISSIONS FROM VEHICULAR MOVEMENT ON UNPAVED ROADS
Studies conducted by the Puget Sound Air Pollution Control Agency
and Midwest Research Institute were used to determine an emission
factor per vehicle for particulate matter (Appendix C). The
average speed of a haul truck on an unpaved road is 32 km/hr. By
adjusting values reported at other speeds through a linear cor-
rection factor, a range of emission factors for particle sizes
<30 ym ..is obtained. For example, a value reported by Midwest
Research Institute of 0.95 g/vehicle-m at 48 km/hr and 2 ym to
30 ym is adjusted to 32 km/hr by the factor (32/48), yielding
0-63 g/vehicle-m. The following table results.
TABLE B-l. EMISSION FACTORS CORRECTED TO AVERAGE SPEED
Reported value, Speed, Particle Corrected value
g/vehicle-m km/hr size, ym g/vehicle-m
Puget Sound Agency
0.03
0.12
0.08
0.65
0.68
0.12
1.47
16
16
32
32
32
48
48
<2
<10
<2
<10
<10
<2
<10
0
0
0
0
0
0
0
.06
.24
.08
.65
.68
.08
.98
Midwest Research Institute
0
0
0
1
1
1
.77
.95
.882
.05
.025
.22
48
48
48
48
64
64
2
2
2
<2
to
<2
to
<2
to
30
30
30
0
0
0
0
0
0
.51
.63
.59
.70
.51
.61
From the corrected values, an average of 0.49 ± 0.28 g/vehicle-m
is calculated as the emission factor from vehicular movement on
unpaved roads due to the transport of sand and gravel.
28
-------
EMISSIONS FROM THE WINDBLOWN TRUCK BED
For emissions from the windblown truck bed, the emission factor
for coal storage is used (7).
270 g/metric ton-yr at 16 km/hr and density of 0.8 x 106 g/m3
Correcting for 48 km/hr, the maximum speed of the trucks, and
1.6 x 106 g/m3, the density of sand and gravel, the factor
becomes
270 g/metric ton-yr
16 / \0.8 x 106,
= 29,160 g/metric ton-yr (B-l)
(The quantities in Equation B-l are cubed and squared due to
proportionalities developed in the coal storage program.) This
factor is based upon 0.45 m2 of surface per ton of coal stored.
The emission factor will therefore have to be corrected for the
geometry of the truck. For a 21-metric ton truck,
n1 4. • *. J-06 g m3 1
21 metric ton •
metric ton 1.6 x 10° g 1.5 m deep
= 8.8 m2 (B-2)
the area is 8.8 m2 . The emissions for a single truck will thus
be
™ n ™ / j_ • j. metric ton 8 . 8 m2
29,160 g/metric ton-yr • Q,45 m2 • vehicle
= 5.7 x 105 g/yr-vehicle (B-3)
Adjusting for plant operating hours,
/260 day/yr\ / 9 hr/day\
r- -, -,o
5.7 x 10 - 365 day/yr 24 hr/day
= 1.5 x 10 5 g/yr-vehicle or 17 g/hr-vehicle (B-4)
On the basis of 1 hr, a representative plant is using 22
vehicles. Therefore,
22 vehicles • 17 g/hr-vehicle = 374 g/hr or 0.10 g/s (B-5)
This is only 2% of the 6.6 g/s caused by vehicular movement
(Appendix D) . The windblown emissions are therefore insignifi-
cant compared to unpaved road emissions.
29
-------
APPENDIX C
LITERATURE SURVEY
EMISSIONS DUE TO VEHICULAR MOVEMENT ON UNPAVED ROADS
Emissions from vehicular movement are due to vehicle-generated
air turbulence and mechanical forces of tires on the road sur-
face. Emissions, E (g/vehicle), are affected by several factors
which can be used t8 relate dependent and independent variables
in equation form:
• vehicle speed, V, km/hr
• number wheels/vehicle, N
• particle size distribution, P, %
• surface moisture, M, or P.E. index
• vehicle weight, T, metric tons
• vehicle cross section, A, m2
• tire width, W, m
• length of unpaved road, L, m
The literature search yielded only scattered quantitative infor-
mation on emissions from unpaved roads. Most of the reported
studies were directed toward quantifying the influence of
vehicle speed on unpaved road emissions.
Vehicle Speed
Table C-l lists results of various tests conducted on emissions
from unpaved roads.
The study conducted by the Puget Sound Air Pollution Control
Agency can be used to predict a mathematical relationship for the
emission of respirable particles from unpaved roads. Their
results show that emissions of particles <2 ym in diameter are
proportional to the vehicle speed, and those <10 ym in diameter
are proportional to the square of the vehicle speed. Based on
this study, one can expect emissions of respirable particles
(<10 ym) to be proportional to (aV2 + bV) where a and b are
constants. Then
E = (aV2 + bV) (C-l)
u
30
-------
TABLE C-l. TESTS OF UNPAVED ROAD EMISSIONS
Investigator
Type
Sampling site of road
Vehicle
speed,
km/hr
Emission
factor,
g/veh-m
Particle size
distribution, yim
Anderson, C. (16)
School of Engineering,
University of New Mexico (16)
Pedco-Environmental
Specialists, Inc. (17)
Bernalillo County, NM Dirt
University of NM Dirt
Sante Fe, NM
Engineering Research Institute, Powshiek County, IA
Iowa State University
Dirt
Dirt
48
40
24
40
56
64
0.14 to 0.20
0.26
0.01
0.19
0.28
0.56
0.99
1.55
No designated size distribution.
<6
<3
_a
_a
_a
a
Puget Sound Air Pollution Duwamich Valley, WA Gravel 16 0
Control Agency (18) 0
0
32 2
2
0
0
0
48 3
1
0
Midwest Research Franklin County, KS Gravel 48 1
Institute (19) 0
0
Gravel 48 1
1
0
Gravel 64 1
1
1
Morton County, KS Dirt 48 2
1
1
Dirt 64 0
0
0
Wallace County, KS Dirt 48 6
5
3
.62
.12
.03
.40
.48
.65
.68
.08
.92
.47
.12
.135
.950
.770
.0
.05
.882
.705
.22
.025
.33
.25
.05
.597
.597
.512
.82
.35
.72
a
<10
<2
a
~a
<10
<10
<2
a
<10
<2
>30
2 to
<2
>30
2 to
<2
>30
2 to
<2
>30
2 to
<2
>30
2 to
<2
>30
2 to
<2
30
30
30
30
30
30
(16) Anderson, C. Air Pollution from Dusty Roads. In: Proceedings of the 1971 Highway
Engineering Conference, (Bulletin No. 44-NMSU-EES-44-71, Las Cruces, New Mexico, 1971.
12 pp.
(17) Investigation of Fugitive Dust Sources, Emissions, and Control. Contract 68-02-0044, U.S.
Environmental Protection Agency, Research Triangle Park, North Carolina, May 1973. 152 pp.
(18) Roberts, J. W., A. T. Rossano, P. T. Bosserman, G. C. Hofer, and H. A. Watters. The
Measurement, Cost and Control of Traffic, Dust and Gravel Roads in Seattle's Duwamish Valley.
In: Proceedings of the Annual Meeting of the Pacific Northwest International Section of the
Air Pollution Control Association, Paper No. AP-72-5, Eugene, Oregon, 1972. 10 pp.
(19) Cowherd, J., Jr., K. Axetell, Jr., C. Guenther, F. Bennett, and G. Jutze. Development of
Emission Factors for Fugitive Dust Sources. EPA-450/3-74-037, U.S. Environmental Protection
Agency, Research Triangle Park, North Carolina, June 1974. 172 pp.
31
-------
where E = emissions in g/vehicle
V = vehicle speed
a, b = constants
Number of Wheels
A vehicle moving on an unpaved road generates dust in proportion
to the number of its wheels:
u
N
(C-2)
where N = number of wheels per vehicle
Particle Size Distribution of the Road Surface Material
Particles >100 ym are moved by saltation and surface creep and
are deposited in or near the affected area. Particles <100 ym
are moved by wind mostly by suspension and are carried over long
distances from their sources. Thus, smaller particles from
unpaved road emissions have a significant impact on ambient air
particulate levels. Wind tunnel studies and open field measure-
ments show that the proportion of movement by suspension is
approximately equal to the proportion of particles <100 ym found
in the soil (20).
u
(C-3)
where
P = percent of particles in the road surface material
(0 cm to 10 cm depth) <100 ym
Surface Moisture
As particle moisture increases, the cohesive force between
particles increases and the rate of soil entrainment therefore
decreases. The rate of soil movement varies inversely as the
Saltation refers to movement of particles (100 ym to 500 ym) in
a series of short bounces, and surface creep refers to the
rolling and sliding of particles (>500 ym) along the surface of
the ground. Soil movement in saltation occurs below a height
of 0.6 m to 1.0 m above ground level; over 90% of the soil
transported by saltation is below a height of 0.3 m from
ground level (20).
;20) Chepil, W. S. Dynamics of Wind Erosion: I. Nature of the
Movement of Soil by Wind. Soil Science, 60(4):305-320 ,
1945.
32
-------
square of its moisture content (21). However, soil surface
moisture data are not available for different regions; hence,
surface moisture is assumed to be proportional to the Thornth-
waite P.E. Index. The P.E. Index, determined from total annual
rainfall and mean annual temperature (22) , is shown in Figure
C-l.
- (c~4)
Vehicle Weight, Vehicle Cross Section, and Tire Width
No quantitative data are available in the published literature on
how these factors influence unpaved road emissions.
Distance of Unpaved Road, L
A vehicle generates dust in proportion to the length of unpaved
road, L.
E oc L (C-5)
where L = the length of unpaved road.
Conclusions
Based on available data in the published literature, emissions
from unpaved roads can be expressed as
K (aV2 + bV) P N
Eu = — - - - f
where E = emissions in g/vehicle
K = constant of proportionality
(21) Chepil, W. S., W. H. Siddoway, and D. V. Armburst. Climat-
ic Factor for Estimating Wind Erodability of Farm Fields.
Journal of Soil and Water Conservation, 17:162-165, 1962.
(22) Thornthwaite, T. W. Climates of North America According to
a New Classification. Georgraphic Review, 21:633-635. 1931,
33
-------
EMISSIONS DUE TO WIND EROSION OF SAND AND GRAVEL DURING TRANSPORT
No quantitative data are available in published literature on
emissions due to wind erosion of sand and gravel during trans-
port. However, data from investigations of similar problems have
been reported (23-25).
Emissions due to wind erosion of sand and gravel are comparable
to those due to wind erosion of land surfaces. The wind erosion
equation as developed by Woodruff and Chepil (23, 24) can be
expressed in the following form:
E =
S
K
(C-7)
where E = emissions due to wind erosion in kg/m2-yr
>b>
K = function of soil or knoll erodibility, surface
s crust stability, and ridge roughness.
U = wind speed.
D = unsheltered distance along the prevailing wind
erosion direction.
d' = variable exponent, a function of K and U3/PE2.
ID
Furthermore, a comparison can be made with emissions from coal
storage piles due to wind erosion. The following equation was
derived based on an analysis of results of wind tunnel experi-
mentation conducted by Pittsburgh Mining and Safety Center,
Pittsburgh, Pennsylvania (25).
K
Ec =
(23) Woodruff, N. P., and F. H. Siddoway. A Wind Erosion
(25) Smger, J. M. , E. B. Cook, and J. Grumer. Dispersal of
^??o and Rock Dust Deposits. Report of Investigations No
/642, U.S. Department of the Interior, Bureau of Mines
Washington, D.C., 1972. 32 pp. uines,
34
-------
where E = emissions due to wind erosion of coal
c storage pile in kg/hr
p = bulk density
s = surface area
a',b',c' = exponents expected to be in the range
2.6
-------
103
Figure C-l. Map of P.E. values for state climatic divisions
36
-------
PI-HMLE 43 N KOKifi CKOTnti S SOB1,,r,ST
I r 62 C 89
Figure C-l (continued)
37
-------
Figure C-l (continued)
38
-------
APPENDIX D
SOURCE SEVERITY CALCULATIONS
PARTICULATES
Source Severity
The source severity, for particulates, S , is given as
A m n c
S =
Dl .8 14
where Q = emission rate, g/s
D = representative downwind distance, m
This equation involves the derivation of downwind ground level
concentrations from an open source when Q and D are known. The
derivation is presented in Reference 7.
The average size of a sand and gravel plant is 6.40 x 10 5 metric
tons/yr. At 9 hr/day and 260 days/yr, the average production
rate is equal to 274 metric tons/hr. Since the average size of
a haul truck is 21 metric tons, the vehicular traffic around
the plant is 11 vehicles/hr. One truck makes two trips on the
unpaved road per load; therefore, traffic doubles to 22 vehicles/
hr . The average distance of unpaved road is 2.2 km, and the
average emission factor for particulates is 0.49 g/vehicle-m for
a vehicle traveling at 32 km/hr . Consequently, the emission rate,
Q, is obtained from
/ 0.49 g \ /22 vehicles\ L _ , \ / hr \ /I, OOP m
Q = vehicle-mj ( - hr - j (2 ' 2 kmj ^37600^ -
/ 0.4
= (vehi
=•6.6 g/s (D-2]
The representative distance, D, for use in Equation D-l is taken
as the distance of the unpaved road from the finished stockpile
to the nearest highway. Hence, the maximum source severity, S ,
is
39
-------
S = ^^ = 0>Q2 (D_3)
Affected Population
The distance from the source to that point where the source
severity is 0.1, Xq , is calculated from
P \ P /
where S =0.1
P
Hence,
) (6.6) I
-1 J
/1 . s i
X_ = ,. = 98Q m (D_5)
p
Since the above value is less than the representative distance
(2,200 m), the population affected by sand and gravel plants is
zero.
FREE SILICA
Source Severity
The source severity for free silica emissions, S , is given as
o
c 316 Q ,_ ,,
S = ^ (D-6)
b D1.814 . TLV
Average free silica content is 14%. Hence, the TLV is 10/
(14 + 2) = 0.625 mg/m3. Therefore,
S = (316) (6.6) = 2.9 (D-7)
(2,200) ! -814 (0.625 x 10~3) *
Affected Population
The distance from the source to that point where the source
severity is 0.1, X , is calculated from
O
s
X =/ 316 Q
s \TLV • S
40
-------
For Sg = 0.1,
(316) (6.6)
X
S
s (0.625 x 10~3) (0.1)
= 14.0 km (D-9)
For Sg = 1.0
XS
(316) (6.6) /l.814
's (0.625 x ID"3) (1.0)
= 3.9 km (D-10)
Since the representative distance is 2.2 km, the affected area is
TT (14.02 - 2.22) = 600 km2 (D-ll)
For a representative population density of 50 persons/km2, the
affected population is 30,000 persons for S > 0.1. Since
S
TT (3.92 - 2.22) = 33 km2 (D-12)
The affected population is 1,650 persons for S > 1.0.
5
41
-------
APPENDIX E
FREE SILICA DISTRIBUTION
Emissions of dusts occur due to vehicular movement on unpaved
road surface while transporting sand and gravel. Information is
available on the magnitude of unpaved road emissions but not on
the free silica composition of emissions. Hence, 30 sand and
gravel plants were randomly selected, and samples of unpaved
road surface were collected from 28 of these for free silica
analysis. Procedures for sample collection, size separation of
respirable particles, and free silica analysis are described in
the following sections.
PROCEDURE FOR SAMPLE COLLECTION
A scoop, sampling jar, and recommended procedure for grab
sampling were sent to each of the 28 sand and gravel plants.
Procedures that were sent to industry for selecting grab sampling
locations and taking samples are shown below:
Procedure for Choosing Grab Sampling Spots
• Note the approximate distance of the unpaved road from the
finished stockpile to the nearest paved highway -
• Divide the unpaved road into four equal sections.
• Take two grab samples from each section as shown in
Figure E-l (one from the center of the lower half and one
from the center of the upper half).
Distance of unpaved road = L *
L/4
L/4 ~ L/4 " L/4
X denotes spots for grab sampling
Figure E-l. Schematic for selecting grab-sampling spots
42
-------
Procedure for Taking a Grab Sample
• Use a hand shovel to scoop samples from the top 1-in. layer
of unpaved road surface. Collect about 1/4 Ib sample from
one spot.
• Samples from different spots can be collected in one jar
(total weight of samples about two pounds); samples should
be labelled and shipped to: Monsanto Research Corporation,
1515 Nicholas Road, Dayton, Ohio 45407, Attn: P- K. Chale-
kode .
SEPARATION OF RESPIRABLE DUST FROM SAMPLES
Samples obtained from sand and gravel plants were dried at 105°C
for about 12 hr to drive off any moisture present. The respir-
able fraction of the dried sample was then separated using an
experimental setup as shown in Figure E-2.
BLEED
V
A
CLOUD
CHAMBER
5 HOLES, 1/16 IN.
"DIAMETER
SANDBLAST GUN
ORIFICETAPS
PUMP
Figure E-2.
Experimental setup for separating
respirable fraction from sample.
The dried sample was sieved through a 60-mesh screen to separate
the particles which were <250 ym. A mini-sandblast gun was used
to spray the sample into a cloud chamber to create a "dusty
atmosphere." A vacuum pump was used to pull the "dirty air"
through an elutriator and a cyclone separator prior to final
collection on a Nucleopore® filter. A flow of 1 cfm was main-
tained through the cyclone and elutriator. The elutriator was
sized so that at 1 cfm, the throughput velocity was 1 cm/s,
which is the terminal velocity for a particle 15 ym in diameter.
43
-------
Thus, particles >15 ym settle in the elutriator. The cyclone
separator described in EPA Method 5 for stack sampling was used
to separate respirable particles <7 ym. This cyclone separator
removes about 99% of the particulate having a spherical equiva-
lent diameter above 7 ym. Nucleopore filters were used to
collect respirable particles, which were then analyzed for free
silica.
The sandblast gun, cloud chamber, elutriator, cyclone separator,
filter holder, and all connecting lines were cleaned well before
starting a new sample analysis Two runs were made for each
sample. The first run lasted about 15 min and was used to
determine the sampling time required for the second run in order
to collect a weight of respirable dust on the filter equal to
the filter tare weight. Samples collected in the second run were
analyzed for free silica.
FREE SILICA ANALYSIS
The infrared spectrophotometric approach is the method chosen
for this study. Although several procedures can be adapted to
these types of speciments, we propose to use the method developed
by Cares, et al (26) for determining quartz in airborne respir-
able granite dust. The method involves ashing of the filter and
sample at 550°C and mixing and pressing the sample ash with KBr
to form a solid pellet which is placed in an infrared spectro-
photometer for spectral analysis. The detailed analytical
procedure is as follows.
1. The sample is taken on a low ash polyvinyl chloride
membrane filter, which has excellent moisture stability
(Mine Safety Appliances Co. Membrane Filter, Part No.
62513 or equivalent) (Note: The infrared spectrum of
the ash from the MSA filter does not interfere with
the quartz determination.)
2. Place the filters in porcelain evaporating dishes
(Coors 4/0) and transfer them to a muffle furnace.
3. Heat to 550°C and maintain until the carbon is dfes-
troyed (about 1-1/2 hr to 2 hr).
4. Remove the dishes carefully, cover, and cool.
[26) Cares, J. W., A. S. Goldin, J. J. Lynch, and W. A. Burgess.
The Determination of Quartz in Airborne Respirable Granite
Dust by Infrared Spectrophotometry. American Industrial
Hygiene Association Journal, 34 (7): 298-305 , July 1973.
44
-------
5. Add 40 mg + 5 mg of infrared-quality KBr (Harshaw
Chemical Co., Cleveland, Ohio) previously ground to
-200 mesh and kept in an oven at 110°C. (If sample
weight is excessive, a larger amount of accurately
weighed KBr should be added and aliquots taken for
final sample.)
6. Mull the sample ash and KBr with a small alundum pestle
until they are thoroughly mixed. Take care not to
grind or apply pressure as this may alter the spectrum.
7. With a spatula, transfer the mixture as completely as
possible to a pellet press equipped with a 6.4 cm
(1/4 in.) diameter punch and die.
8. 'Tap lightly to distribute the powder evenly, center the
punch carefully, and press. Release the pressure,
turn the die about 180°, and repeat the pressing. With
good technique, a clear pellet without cracks or opaque
spots will be obtained.
9. Transfer the pellet to a pellet holder and place the
mounted pellet in the sample beam of an infrared
spectrophotometer (Perkin-Elmer Model 421 Grating
Spectrophotometer or equivalent).
10. At a wavelength of about 11.8 ym and wide slit, adjust
the base line to a maximum transmission (or minimum
absorbance) and scan to 13 ym. For identification
purposes, observing the 14 ym quartz band may be
necessary. Reverse the sample for a repeat scan.
11. To obtain the weight of quartz in the sample, subtract
the absorbance of the base line at 12 ym from that at
12.5 ym and compare the net absorbance with a calibra-
tion curve obtained from a series of quartz-KBr stand-
ards. Absorbances should be below 0.5 for satisfactory
linearity. Samples of greater absorbance are brought
into this range by breaking up the pellet, diluting it
with KBr, and aliquoting it if necessary- Assuming
100% sample recovery and a minimum possible measurement
of absorbance of 0.02, the detection limit is ^5 yg of
quartz in a sample.
Preparation of calibration standards is done as follows:
1. Prepare quartz standards from 5 ym grade Minusil R, a
high-purity crystalline silica obtainable in several
size ranges from the Pennsylvania Glass Sand Corp.,
Pittsburgh. Ninety-eight percent of the particles of
this grade are <5 ym in diameter.
45
-------
2. Place the standards in a muffle furnace and heat them
to the same temperature as the samples before use.
3. Prepare stock standards by blending carefully weighed
amounts of Minusil and R-grade KBr either by mulling
5-ym grade Minusil R and infrared-quality KBr with an
alundum mortar and pestle or by using a commercial
type of mixer, such as the "Wig-L-Bug."
4. Dilute the stock mixture in the same manner to obtain
concentrations which will yield 40 mg of pellets con-
taining from 5 yg to 150 yg of quartz.
5. Press pellets and record spectra in the same manner as
with the samples.
6. Plot calibration curve of net absorbance versus weight
of quartz.
RESULTS OF FREE SILICA ANALYSIS
Results of the free silica analysis are shown in Table E-l and
in Figure E-3. The free silica values quoted at each site are
accurate within ±20%. The highest value of free silica is 47%
(near Cleveland, Ohio) and the lowest value is 1.4% (near
Toledo, Ohio). The mean value is 14.1% with a standard deviation
of ±12.0% and a 95% confidence level of 4.6%.
NUMBERS INDICATE THE
PERCENT OF FREE SILICA
FROM SAND AND GRAVEL PLANTS
AT THE LOCATIONS SHOWN.
Figure E-3. Free silica distribution,
46
-------
TABLE E-l. RESULTS OF FREE SILICA ANALYSIS
Sample
number
1
2
3
4
5a
5b
6a
6b
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
City and state
Parker sburg, WV
Dayton, OH
Garwood , TX
Milwaukee, WI
Kosse, TX
Kosse, TX
Jay , ME
Jay , ME
Elgin, IL
Greenville, MS
Blenheim, SC
Fergus Falls, MN
Indio, CA
Orange County, CA
Des Moines, IA
College Station, TX
Pittsburgh, PA
Grand Rapids , MI
Grey Cloud Township, MN
Kalamazoo, MI
Oxford, MI
Fort Wayne , IN
Indianapolis, IN
Thompson, OH
Clay Center, OH
Littleton, CO
Redmond , WA
Denver, CO
Mt. Carmel, IL
Mean value
Standard
deviation
95% Confidence level
Free silica, %
32.4
1.7
42.4
7.4
8.3
10.2
5.6
5.5
9.2
43.7
10.4
12.7
9.9
12.2
12.7
16.9
20.0
8.1
13.5
11.6
13.3
8.7
10.5
47.0
1.4
6.5
5.2
4.7
18.1
14.1
±12.0
±4.6
a
95% confidence level = t • o/ \/n-l
where t = student's t, 2.048
a = overall standard deviation
n = number of samples
47
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GLOSSARY
affected population: Product of the land area where severity is
greater than 0.1 or 1.0 and the representative population
density.
confidence interval: Range over which the true mean of a popu-
lation is expected to lie at a specific level of confidence.
criteria pollutant: Pollutant for which ambient air quality
standards have been established.
emission burden: Ratio of the total annual emissions of a
pollutant from a specific source to the total annual state
or national emissions of that pollutant.
fibrosis: Abnormal increase in the amount of fibrous connective
tissue in an organ or tissue.
free silica: Crystalline silica defined as silicon dioxide
(Si02) arranged in a fixed pattern (as opposed to an
amorphous arrangement).
growth factor: Ratio of known to projected emissions from a
source type.
hazard factor: Measure of the toxicity of prolonged exposure
to a pollutant.
lignin sulfonates: Organic substances forming the essential
part of woody fibers introduced into the sulfonic group by
treatment with sulfuric acid.
precipitation-evaporation index: Reference used to compare the
precipitation and temperature levels of various P.E.
regions of the U.S.
representative source: Source that has the mean emission
parameters.
severity: Hazard potential of a representative source defined
as the ratio of time-averaged maximum concentration to the
hazard factor.
48
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silicosis: Chronic disease of the lungs caused by the continued
inhalation of silica dust.
silt-sized: Fine particle sized, as soil or sand.
threshold limit value: concentration of an airborne con-
taminant to which workers may be exposed repeatedly, day
after day, without adverse affect.
49
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-600/2-78-004y
i.
3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
SOURCE ASSESSMENT:
TRANSPORT OF SAND AND
GRAVEL
6. REPORT DATE
October 1978 issuing date
6. PERFORMING ORGANIZATION CODE
7 AUTHOR(S)
J. C. Ochsner, P. K. Chalekode, and
T. R. Blackwood
8. PERFORMING ORGANIZATION REPORT NO
MRC-DA-721
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Monsanto Research Corporation
1515 Nicholas Road
Dayton, OH 45407
1O. PROGRAM ELEMENT NO.
1BB610
11. CONTRACT/GRANT NO.
68-02-1874
12. SPONSORING AGENCY NAME AND ADDRESS
Industrial Environmental Research Lab.
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
- Cinn,OH
13. TYPE OF REPORT AND PERIOD COVERED
Task Final, 8/74 - 9/77
14. SPONSORING AGENCY CODE
EPA/600/12
15. SUPPLEMENTARY NOTES
IERL-Ci project leader for this report is John Martin, 513-684-4417
This report describes a study of atmospheric emissions from the transport
of sand and gravel on unpaved roads. The potential environmental effect
of this emission source was evaluated using source severity, defined as
the ratio of the time-averaged maximum ground level concentration of a
pollutant at a representative plant boundary to a hazard factor. The
hazard factor is the ambient air quality standard for criteria pollutants
and an adjusted threshold limit value for noncriteria pollutants. A
representative sand and gravel plant processes 274 metric tons/hr, with
vehicular traffic of 22 vehicles/hr. The average unpaved road length of
sand and gravel plants is 2.2 kilometers, and each truck carries an aver-
age of 21 metric tons. The uncontrolled particulate emission factor for
the industry due to vehicular movement is 87 g/metric ton. The source
severities for particulates and free silica-containing particulates are
0.02 and 2.9, respectively.
Some plants have effectively used certain control measures, such as
application of oil and chemical solutions into the road surface. Future
control techniques would consider the emission-influencing factors of
vehicle speed, vehicle size, number of wheels, tire width, partj.de size
distribution, and road moisture content.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
Air pollution
Dust
Silicon dioxide
Sands
Gravel
b.IDENTIFIERS/OPEN ENDED TERMS
Air pollution control
Stationary sources
Source severity
Particulate
c. COSATI Held/Group
68A
8. DISTRIBUTION STATEMENT
RELEASE TO PUBLIC
19 SECURITY CLASS (Thii Rtpon)
Unclassified
21. NO. OF PAGES
62
20 SECURITY CLASS (This page t
Unclassified
22. PRICE
EPA Form 2220-! («-73)
50
»US GOVERNMENT PRICING OFFICE 1978-657-060/1503
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