EPA-450/3-76-026a
June 1976
NATIONAL ASSESSMENT
OF THE URBAN
PARTICIPATE PROBLEM
Volume III -
Denver
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Air and Waste Management
Office of Air Quality Planning and Standards
Research Triangle Park, North Carolina 27711
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EPA-450/3-76-026a
NATIONAL ASSESSMENT OF THE URBAN
PARTICULATE PROBLEM
Volume III
Denver, Colorado
FINAL REPORT
by
Cordon L. Deane
Frank Record, Project Director
GCA/Technology Division
Burlington Road
Bedford, Massachusetts 01730
Contract No. 68-02-1376, Task Order No. 18
EPA Project Officer: Thompson G. Pace
Prepared for
ENVIRONMENTAL PROTECTION AGENCY
Office of Air and Waste Management
Office of Air Quality Planning and Standards
Research Triangle Park, North Carolina 27711
June 1976
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This final report was furnished to the Environmental Protection Agency by
the GCA/Technology Division in fulfillment of the requirements under Contract
No. 68-02-1376, Task Order No. 18. The contents of this report are reproduced
herein as received from the contractor. The opinions, findings and conclusions
are those of the authors and not necessarily those of the Environmental Pro-
tection Agency.
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FOREWORD
This document is part of a 16-volume report assessing the urban particulate
problem, which was conducted by GCA/Technology Division for EPA.
This particular document is one of the 14 single city volumes that provide
working summaries of data gathered in the 14 urban areas during 1974 to
support an assessment of the general nature and extent of the TSP problem
nationwide. No attempt was made to perform detailed or extensive analyses
in each urban area. Rather, the city reports are intended as a collection
of pertinent data which collectively form a profile of each urban area. This,
in turn contributes to a comparative analysis of data among the 14 areas
in an attempt to identify general patterns and factors relating to attainment
of the TSP problem nationwide. Such an analysis has been made in Volume I
of the study-National Assessment of the Urban Particulate Problem-National
Assessment. The reader is referred to this volume as the summary document
where the data is collectively analyzed.
This and the other 13 city reports are viewed primarily as working documents;
thus, no effort was made to incorporate all the reviewer's comments into the
text of the report. The comments were, however, considered during the prepara-
tion of Volume I and are included herein in order to alert the reader to
different points of view. The 16 volumes comprising the overall study are
as follows:
Volume
Volume
Volume
Volume
Volume
Volume
Volume
Volume
Volume
Volume
Volume
Volume
Volume
Volume
Volume
I
II
III
IV
V
VI
VII
IX
X
XI
XII
XIII
XIV
XV
XVI
National Assessment of the Urban Particulate Problem
Particle Characterization
Denver
Birmingham
Baltimore
Philadelphia
Chattanooga
Oklahoma City
Seattle
Cincinnati
Cleveland
San Francisco
Miami
St. Louis
Providence
iii
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CONTENTS
Page
Foreword Hi
List of Figures v
List of Tables vii
Acknowledgments ^x
Executive Summary x
Reviewers' Comments x*v
Sections
I Statement of the Problem 1
II Analyses 15
III Summary and Conclusions 74
Appendixes
A Meteorological Data 80
B Particle Characterization 87
iv
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LIST OF FIGURES
Ho. iM
1 TSP Monitoring Stations in the Denver AQCR 7
2 TSP Monitoring Stations in the Denver County Area 8
3 Trends in Count/wide Annual Geometric Means of TSP 11
4 Annual Geometric Means of TSP in the Denver AQCR (yg/m ) 12
5 Annual Geometric Means of TSP in the Denver County Area
(ug/m3) "
6 Average Annual Suspended Particulate Concentrations
Measured in Denver and Surrounding Counties During
1970-1972 I*
7 Area Source Emission Density in the Denver AQCR 19
8 Point Source Emission Density in the Denver AQCR 20
9 Area Source Emission Density in the Denver County Area 21
10 Point Source Emission Density in the Denver County Area 22
11 Location of Point Sources in the Denver County Area 23
12 Location of Point Sources 24
13 Fugitive Dust Emission Density in the Denver AQCR 28
14 Monthly Emission and Above Background TSP Ratios in Denver
(1974) 40
15 Fuel Combustion - Emission Rate Curve for Colorado 44
16 Process Weight Rate Curve for Colorado 45
17 Aver age ^Monthly Mean Morning and Afternoon Mixing Heights
and County-Wide Monthly/Annual Geometric Means of TSP in
Denver 54
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LIST OF FIGURES (continued)
No. Page
18 Typical WNW-ESE Profile of Pollution Layer Depths Over
Metropolitan Denver Between 0800 and 1500 on Days When
Temperature Inversions are not Eliminated 57
19 Average Wind During Pollution Episodes From 10 a.m. to
2 p.m. (a, b, c) 58
20 Percent of Observations Versus Wind Direction in Denver 59
21 Normal/Yearly Precipitation and TSP Concentration at
Denver NASN Station, 1957 to 1974 61
22 Normal/Yearly Precipitation and County-Wide Annual Geometric
Mean/6-Ye-.r Mean, 1969-1974 63
23 Average Monthly/Monthly Precipitation and Countywide
Monthly Geometric Mean/Annual Geometric Mean for TSP
in Denver, 1974 64
24 Yearly Rainfall in Denver 81
25 Monthly Rainfall in Denver 82
26 Monthly Number of Days of Rain in Denver 83
27 Yearly Heating Degree Days in Denver 84
28 Monthly Heating Degree Days in Denver 85
29 Monthly Windspeed in Denver 86
30 Cumulative Size Distributions for Three Particle Types,
State Health Building, Denver, January 25, 1974 98
31 Cumulative Size Distributions for Three Particle Types,
State Health Building, Denver, June 14, 1974 99
32 Cumulative Size Distributions for Three Particle Types,
School Administration Building, Denver, June 14, 1974 100
vi
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LIST OF TABLES
No. Page
1 Forecasted Annual Rates of Employment Growth, Metropolitan
Denver 1970 to 2000 4
2 Characteristics of Monitoring Sites in the Denver AQCR 9
3 Particulate Emissions in the Denver AQCR, by County 16
4 Fugitive Emissions in the Metropolitan Denver AQCR 26
5 Denver AQCR Fugitive Dust Inventory 27
6 Particulate Emission Densities and TSP Concentrations
(1972-1973) at Monitoring Sites in the Denver AQCR 29
7 Differences in Point and Area Source Emission Inventories
of Particulates in the Denver AQCR, 1970-1975 32
8 Calculated Particulate Concentrations Due to Point Sources 33
9 Percentage Contribution of Particulate Source Sectors in
the Denver AQCR 35
10 Comparison of Actual and Projected Changes in TSP Concen-
trations in the Denver AQCR 36
11 Estimated Monthly Emissions of Particulates in Denver
County 38
12 Analysis of 1974 TSP Monitoring Sites in Denver 50
13 Percentage of Frequency of Low-Level Inversion 55
14 Comparison of TSP Concentrations Before and After Snowfall
and Rainfall Storms 72
15 Meteorological Data on Selected Sampling Days 90
vii
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LIST OF TABLES (continued)
No. Page
16 Annual Average Concentrations of Sulfate and Nitrate Ions
at the Denver, Colorado, NASN Site No. 060580001 90
17 Results of Filter Analyses for Selected Sites in Denver and
Vicinity 91
18 Composite Summary of Filter Analyses for Selected Sites in
Denver and Vicinity 95
19 Results of Replicate Analyses of Denver Filters 96
20 Citywide Composite Summary of Filter Analysis in Denver 97
21 Detailed Physical Examination: State Health Building,
Denver, June 14, 1974 101
viii
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ACKNOWLEDGMENTS
GCA/Technology Division wishes to sincerely thank those persons and organi-
zations who made significant contributions to this effort. On-going project
supervision was provided by Thompson G. Pace of EPA's Control Programs
Development Division. The case study in Denver was greatly assisted by
the cooperation and helpfulness of the staff of the Colorado Air Pollution
Control Division, particularly Wayne May, Todd Reynolds, Hank Dequasie,
and John Clause. In addition, valuable information was provided by
Richard Young of the Denver Department of Health and Hospitals, Air Pollu-
tion Control Section, and Messrs. Fondi and Herzeberger of the Denver
Department of Public Works.
ix
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EXECUTIVE SUMMARY
The report summarized herein presents the analyses of the partlculate
situation In the Metropolitan Denver Air Quality Control Region (AQCR)
conducted as part of the study for the national assessment of the problem
of attainment or nonattainment of the National Ambient Air Quality Stan-
dards for participates. The Denver AQCR represents a lightly Industri-
alized area, with above average heating requirements and less than average
amount of rain, that has had some success In reducing emissions but not
partlculate concentrations. Sanding for snow control and other fugitive
dust sources have been Implicated as a major contributing sources to the
ambient levels of partlculates In Denver so this report provides special
emphasis In that area.
In addition to the analyses of sanding activity, analyses of the air
quality levels, emissions, regulations, monitoring network, meteorology,
and street sweeping are Included In this report. The major findings In
each of these areas are summarized below in the order in which they ap-
pear in the text.
AIR QUALITY
There have been no real trends in TSP levels during the past 6 years in
the AQCR though Denver County has shown some improvement in its, air qual-
ity since 1965. The primary annual air quality standard is being ex-
ceeded at most sites around the AQCR and the secondary annual air quality
standard is being exceeded at all but one site. The highest annual geo-
2
metric mean was 131 pg/m , 8 percent higher than that used in the SIP for
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strategy planning. Violations of the 24-hour standards have also been
frequent with the secondary standard exceeded occasionally at most of
the monitors in 1974.
The spatial distribution of the air quality is primarily the result of
the topography with highest levels near the river bed and the levels
decreasing in the suburban and rural areas on higher ground. The county-
3
wide geometric mean of all stations in Denver County was 97 yg/m .
EMISSIONS
The determination of emission levels in the Denver AQCR has been through
several iterations, each with the purpose of strategy planning. However,
each of these iterations has produced substantially different emission
inventories with no consistent trend pattern. Therefore, no correlation
can be drawn between changes in emissions and TSP concentration.
The study of fugitive emissions has also produced two different inven-
tories with considerably different values. While the one study that was
specific to the State of Colorado is expected to be more accurate, this
inventory had serious questions raised about it in the course of this
study.
REGULATIONS AND SURVEILLANCE
The Colorado Air Pollution Control Commission (CAPCC) is responsible for
the control of particulate matter throughout the State of Colorado. How-
ever, in the City of Denver, the sources are controlled by both the city's
regulations and the applicable ones of the CAPCC. The two sets of regu-
lations are equivalently stringent. Surveillance of the sources are per-
formed through the use of the permit system, visible emissions, and com-
plaints. Only a small amount of stack testing to determine compliance is
done; the majority of sources are determined to be in compliance through
theoretical calculations.
xi
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The regulations imposed by the CAPCC were compared with other cities
reviewed in this study and were found to be more stringent in most
cases. Comparison with average regulations in published studies indi-
cated that the city's regulations were at least as stringent as those
normally applied.
NETWORK DESIGN
The monitoring network was found to be generally acceptable except in a
couple of instances. The most noticeable problem occurred in Denver
County where it was felt that monitors should be more centrally located
with respect to weight and in the monitoring of outlying areas away from
population centers. This latter deficiency prevented the provision of
valuable information on the air masses entering the city.
METEOROLOGY
Ventilation and precipitation were the two major meteorological elements
reviewed and analyzed. The study of ventilation included the considera-
tion of the topography of the area.
Ventilation was found to have a significant impact on the concentration
in Denver and is expected to account for much of the observed seasonal
pattern in TSP levels. Denver has the lowest average morning mixing
heights of the cities studied but also the highest average afternoon
mixing heights.
Precipitation appears to have only a minor impact on the ambient concen-
tration where considering annual and monthly means. This was felt to be
due to the generally low level and infrequent occurrence of precipitation;
i.e., the small Impact that occasionally resulted from precipitation was
lost in the calculation of geometric means.
xii
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URBAN ACTIVITY
The major analysis of urban activity was limited to the impact of sanding
operations on the TSP levels. Street sweeping was also considered but in-
sufficient information was available for the determination of any
correlation.
The analysis of sanding included a review of the calculation of the total
tonnage of emissions due to sanding in Denver County, the results of which
indicated that the emission estimates currently being used for planning
purposes may over-emphasize the importance of sanding. Seasonal fluctua-
tions in emissions, meteorology, and air quality were also studied and
this analysis provided further support to the view that the current fugi-
tive dust inventory was misleading.
Daily fluctuations in TSP levels in response to sanding for snow control
provided no firm evidence of the impact of sanding on the TSP levels.
CONCLUSIONS
The results of this study indicated that a major part of understanding the
problem of lack of attainment of the NAAQS in the Denver AQCR could be
attributed to the lack of sufficiently accurate and detailed information
for strategy planning. Recommendations for steps to be taken for the
eventual attainment of the standards Included further emission inventory
studies for both fugitive and traditional sources, expansion of the
monitoring network, and the increased consideration of the meteorological
and topographical influences.
xiii
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REVIEWERS' COMMENTS
The draft report for each city was submitted to interested EPA, state,
and local officials for comment on the contents and findings. Comments
of an editorial nature were reconciled; comments of a substantive nature
which reflect differences of opinion were compiled and are presented
below.
Page xiii - Network Design - It is impossible to have all
samplers at the same height above ground. EPA
criteria specify less than 50 ft above ground.
The Colorado Department of Health sampler is a
bit too high, but has consistently been at the
same location since before 1969; therefore, com-
parison of data with that of previous years should
be of value. We disagree with the concept that
information on air masses entering Denver can be
obtained from 24-hour hi-vol samples. Wind data
are available from several sites in the Metro
area for use in evaluating flow patterns.
- Meteorology - Seasonal influence of precipitation
becomes evident if comparisons are made. The two
winter quarters added together are consistently
higher than the two summer quarters. Spring and
summer rainshower activity plus lawn irrigation
tend to "clean" all major traffic lanes.
Page xiv - Conclusion - We doubt that expansion of the
network in the Denver AQCR would give us any
more useful information. We exceed considerably
the EPA requirements for number of samplers for
the region.
The many studies already completed on particulates
and related micrometeorology over the Denver Region
point up the relatively high background level of
TSP. The present standards seem to be entirely too
xiv
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low - a point not made in this study. Further study
of the problem, better emission inventories, and
more detailed sampling will not enable us to design
strategies for attainment of unrealistic standards.
Page 11 - In Figure 3, single stations are compared with
Figure 3 averages of 4 to 6 stations and are erroneously
considered representing trends.
Page 30 - The discrepancy in monitoring data and inventory data
may also be due to the apportioning of the emissions
done by GCA in the example plan and not only to the
magnitude of the total emissions estimated by PEDCo.
Page 38 - The table contains emissions from sanding. The
cleaning practices in Denver result in large quan-
tities of sand remaining on the street long after
the snow has gone. To estimate emissions, I would
use some kind of factor such as 50 percent. Using
the figures in the table add 1/2 of the quantity to
the next month; i.e.:
589 895
1/2 295 295
884 1,190 2,748 2,777
Applying such a factor would change the estimate of
emissions considerably.
Page 60 - The CAMP station and the NASN station are one and
P. 3 the same site.
Page 51 - It is felt by many that the monitoring in the Denver
P. 2 area is more than adequate. It may be that some
stations should be relocated, however. Any recommen-
dation regarding the addition of stations should be
very specific and justified.
Page 62 - The correlation noted between precipitation and
P. 3 concentration is tenuous.
Page 67 - Here and elsewhere in the report references are made
P. 3 to snow removal which I do not believe generally
exists in the city and street sweeping, which is based
on averages for the city. There is no indication of
what the satellite cities do for each activity. I
believe that these considerations need a second look.
xv
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Page 76 - The statement "In fact the Federal secondary particu-
P. 2 late standard ... is exceeded in almost completely
undeveloped areas" should be substantiated and qual-
ified. It should be pointed out that while 24-hour
values in undeveloped areas are sometimes quite high,
annual geometric means are very low - far below
standards. This is not true for developed areas.
Page 78 - Network Design - People live and work at varying
heights throughout the region. If a sampler shows
violation in TSP at 50 feet, control strategies must
show improvement at that point as well as at ground
level.
General - The conclusions reached in the report are confusing.
Specifically, how does climatology and topography
affect air quality attainment goals?
The recommendations are not justified. Specifically,
recommendations for further air quality and meteoro-
logical monitoring in Denver are not responsible since
there exists appropriate data.
The analysis techniques used were not explained
adequately. For example, it is unclear as to what
dispersion models were used in the analysis and what
data inputs and model verification should have been
done.
A considerable amount of discussion is included relat-
ing particulates to precipitation. In cities of the
Midwest it may be possible to get a good correlation
between particulate and rainfall because much of
the rain is in the form of areawide storms and not
isolated thundershowers. In Denver the summer rain
generally takes the form of isolated storms and they
do not affect the general area.
In general, the analysis uses averaging and data
smoothing techniques. For Denver, I believe that
analysis should go the other direction and become
more site and data specific.
xvi
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SECTION I
STATEMENT OF THE PROBLEM
CHARACTERISTICS OF THE METROPOLITAN DENVER AQCR
The Metropolitan Denver Intrastate Air Quality Control Region (AQCR)
encompasses the counties of Adams, Arapahoe, Boulder, Clear Creek,
Denver, Douglas, Gilpin, and Jefferson. The AQCR extends eastward
from the Continental Divide into the plains, with the major urban
centers located along the foothills of the Rockies. The greater Denver
area lies within the South Platte River drainage basin with the City
of Denver having an elevation in excess of 5,000 feet above sea level.
Roughly 20 miles to the west the mountains reach elevations of 10,000
to 14,000 feet; to the southwest, the land rises more gradually along
the South Platte River valley. In addition to the City of Denver, the
AQCR includes the major urban centers of Boulder, Longmont, and Broom-
field in Boulder County, and Brighton in Adams County.
The particulate problem is basically a result of the arid conditions
of the region which are conducive to entrainment and re-entrainment
of particulares during windy conditions. Fugitive dust, a major com-
ponent of total particulates, has several man-made sources; unpaved
roads, sand on paved roads, agriculture, land development, residential,
industrial, and commercial construction, highway construction, aggregate
storage, cattle feedlots, and quarrying, mining, and tailings. The
pollution problem is exacerbated by the valley effect of the topography
and frequent low level inversions in the winter time.
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Population
The Denver region's population has grown at a fast pace in the past
3 decades, the rate of growth ranging from 3 to 4.6 percent per year.
The Denver Standard Metropolitan Statistical Area (SMSA), encompassing
Adams, Arapahoe, Boulder, Denver and Jefferson Counties, had a 1970
population of 1,227,529. Based on population gains through mid-1973,
the Denver Regional Council of Governments (DRCOG) estimates the
current SMSA population to be approximately 1,416,800. Denver County
contained over 50 percent of the total metropolitan Denver population
in 1960, but it is estimated that by the year 2000 it will only retain
about 25 percent -jf the total. Population is decreasing in the central
city as urban sprawl moves to the north and south along the front range.
The suburban communities accounted for approximately 80 percent of the
area's population increase between 1950 and 1970.
The major components of population change for the Denver urbanized
area Include natural increase through increased births, and net mi-
gration. Of the two, net migration, or the difference between those
coming into the area and those leaving, has been the most important.
Both rural-urban migration and the relative stability of Denver's
economy are cited as primary contributing factors for the large flux
of the residents.
Density of population in the Denver central city, in 1970, was 7,602
per square mile and 198 beyond the central city. In general, this is
a low suburban density and is partially because Denver is relatively
isolated from other major cities. Additionally, people have shown a
preference for open space in the metropolitan area, supported by the
high mobility afforded by the automotive-dominant transportation sys-
ten and extensive highway network. The overriding characteristic of
the region is this low population density and dispersed growth pattern.
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The current patterns of sprawling low density suburban areas have con-
tributed to the regional dependence on private automobile travel.
Employment
The Denver AQCR is a relatively light industrialized area with only
21 percent of its work force in the manufacturing sectors. The metro-
politan Denver region has shown relatively healthy economic perfor-
mance in the past decade, with total employment in the region increasing
by 30 percent between 1964 and 1970. This represents an annual com-
pound growth rate of 4.5 percent per year. The 1970 labor force for
the area was approximately 550,000, with 26,000 employed by the Federal
Government. In addition to the large Federal labor force, the Denver
region also contains State and local government labor forces (City and
County employees) since Denver is the principal governmental and poli-
tical center in Colorado. Approximately two-thirds of the employment
growth between 1964 and 1970 occurred in Denver County, while about
95 percent of the population growth was in surrounding counties.
Based on analysis of industrial groups and employment trends, the Den-
ver Regional Council of Governments (DRCOG) has projected employment
growth trends by industry group to the year 2000 for the metropolitan
Denver area. Table 1 provides the forecasted annual rates of em-
ployment growth for the Denver region by industrial type. These em-
ployment growth projections show that higher than average total em-
ployment growth will be experienced by three industries: (1) finance,
insurance and real estate, (2) services, and (3) government. Approx-
imately average growth will occur in industries: (1) construction,
and (2) wholesale and retail trade. Employment growth rates of two
industrial groups will be consistently below the rate of growth in
total employment: (1) manufacturing, and (2) transportation, com-
munications and utilities. One industry, agriculture, however, is
projected to have a negative growth rate.
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Table 1. FORECASTED ANNUAL RATES OF EMPLOYMENT GROWTH,
METROPOLITAN DENVER 1970 to 2000
Industry category
Agriculture
Mining
Contract construction
Manufacturing
Transportation, communication
and public utilities
Wholesale and retail trade
Finance, insurance and real
estate
Services
Government
Weighted average growth
Forecasted annual rate of growth
1970-1980
percent
-0.8
0.2
3.2
2.8
2.7
3.0
3.8
3.4
3.6
3.1
1980-1990
percent
-1.1
0.4
2.4
2.2
2.7
2.3
2.8
2.6
2.7
2.4
1990-2000
percent
-1.6
0.4
1.9
1.7
1.6
1.8
2.1
2.2
2.4
2.0
Source: The Denver Regional Council of Governments.
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Land Use
The Metropolitan Denver AQCR covers a land area of 13,067 square kilo-
meters (5045 square miles), centered around the Denver Metropolitan
Area, occupying about 712 square kilometers (275 square miles) and
Denver's center city occupying approximately 5 square kilometers in-
cluding a Central Business District (CBD) of 1.4 square kilometers.
General land use trends for the Denver Standard Metropolitan Statis-
tical Area (SMSA) show agricultural and vacant land being transformed
to single-family residential use. Major portions of the urbanized
areas in the region are characterized by single-family tract housing,
strip commercial developments and a substantial freeway network. The
recent decades have shown circumferential development in all directions
from the Denver Metropolitan Area, served by upgraded arterials and
new highways.
The distribution of land uses in the Denver CBD and urbanized regions
of the study area reflects the governmental, financial, service, and
distribution functions that the urban centers perform for the metro-
politan area and the larger Rocky Mountain region. Downtown Denver
is not a manufacturing center, but rather the keystone of business and
government, devoted to the distribution and exchange of goods, money
and ideas. In decreasing order of importance, office space, hotels
and motels, retail activity, and governmental facilities are the primary
land uses in the Denver CBD, followed by residential, storage, com-
mercial services, and industrial uses. A recent inventory of zoning
in the Denver SMSA shows 19 percent or nearly one-fifth of the land
zoned for residential use. Although 61 percent of the land in the
region is still zoned for agriculture, the trend is for rezoning to
higher use (residential, commercial, industrial, and recreational).
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For the Denver SMSA, as a whole, commercial and industrial land uses
have developed in a dispersion pattern around the urban centers.
Commercial growth is mainly attributable to the development of various
neighborhood and regional shopping centers. There has been a con-
tinued dispersion of new industrial development, while diverse changes
are evident in the services, parks and public land uses. New develop-
ment and growth potential will depend upon available vacant space,
transportation accessibility, costs, availability of water resources
and related factors. Land use planning and zoning activities have
varied in the region's areas. Denver and Aurora, for example, have
aggressive annexation policies and promote higher use development of
vacant lands through their zoning regulations.
AIR QUALITY SUMMARY
There are currently 23 stations monitoring for total suspended par-
ticulates (TSP) in the Denver AQCR, as shown in Figure 1. Over half
of these stations are located in or near Denver County and an enlarged
view of this area is given in Figure 2. All of these sites are the
responsibility of the Colorado Air Pollution Control Division (CAPCD)
and have their data reported to NADB. Specific information on the
monitoring sites is given in Table 2. The sites are fairly evenly
distributed between the suburban and center city areas with two monitors
located in rural areas. The stations also have a wide exposure to
residential, commercial, and industrial activity. The height above
ground ranges from 10 feet to 60 feet with many monitors located
in-between and the range of height above mean sea level is even greater
due to the topography of the area.
Except for the National Air Sampling Network (NASN) monitor in Denver,
consistent information on trends in the AQCR was only available back
to 1969 and four of the counties had continuous sampling during this
period limited to one monitor. The county-wide annual geometric means
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4440
4420-
4400-
4380-
4360-
4340-
ARAPAHOE
4320-
I
420
I
440
460
480
500
I
520
I
540
I
560
I
580
I
600
Figure 1. TSF monitoring stations in the Denver AQCR (CAPCD site identification
number)
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00
4386 -
490,4384
KILOMETERS
492 494 496 498 500 902 904 506 90S 910 912 914 916
918.4364
Figure 2. TSP monitoring stations in the Denver County area (CAPCD site
identification number)
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Table 2. CHARACTERISTICS OF MONITORING SITES IN THE DENVER AQCR
vo
County
Mans
Ad BBS
Allans
Adam
Arapahoe
Arapahoe
Arapahoe
Boulder
Clear Creek
Denver
Douglas
Gllpin
Jefferson
CAPCD
no.
88
7
B
SB
11
9
110
19
22
94
2
1
4
96
3
3
60
95
13
59
15
16
56
Location
Westminster
Aurora
Adams City
Brighton
Cherry Creek. Dam
Englevood
Height
above
ground
(feet)
15
20
15
35
4
20
Centenlal Wells | 15
1
Boulder
Longmont
Idaho Spring
State Health Dept.
Hull Photo
Sever Plant
CARIH
School Administration Bldg.
Gates Building
Castle Rock
Black Bawk
Lakeuood
Edgeuater
Arvada
Golden
Rocky Flats
30
30
18
60
Height
above aean
sea level
(feet)
5335
5358
5145
5015
5656
5428
5330
5380
5010
7538
5380
i
25
10
13
50
25
15
40
15
35
15
20
10
5293
5150
5325
5275
5288
6210
8140
5597
5385
5353
5670
5975
Site characteristic
Suburban-residential
suburban
Resldential/cognerclal
Suburban-industrial
center city
Commercial
Remote to suburban
suburban
Resident lal/comerclal
Suburban-residential
Center clty-conBerclal
Center city-commercial
Center city-conmercial
suburban-residential/
Light commercial
suburban
Light industrial
suburban-residential/
Light commercial
suburban
Heavy Industrial
Center city-commercial
Center city-industrial
Center city-commercial
Center city-commercial
Suburban-residential
Suburban-come re lal
Suburban-commercial
Suburban-industrial
Rural-industrial
TSP
1974
geoBetrtc
mean
-------
for each county and the annual geometric means for the NASN station
(1957-1973) are plotted in Figure 3. These plots indicate that
no significant trend pattern has been established in any county
except Douglas, where the TSP concentration has increased steadily,
and in Denver where there is approximately a 20 percent decrease in
TSP levels noted between the 1964-1965 means and the 1969-1974 means.
The primary annual National Ambient Air Quality Standard (NAAQS) of
>
75 ug/m is exceeded in all counties except Clear Creek which had an
annual geometric mean of 73 ug/m .
The spatial distribution of the TSP levels can be estimated from the
plot of the 1974 geometric means given in Figure 4 for the Denver AQCR
and in Figure 5 for the Denver County area. As is evident from these
figures, the primary and secondary standards are exceeded throughout
the AQCR except for Rocky Flats in Jefferson County (CAPCD Number 56)
and the area of maximum concentration is centered along the South Platte
River. This distribution of concentration is not substantially changed
from the time of the submission of the Air Quality Implementation Plan
for the State of Colorado. (See Figure 6.)
10
-------
200
190
ISO
170
160
ISO
140
ISO
IZO
no
100
»0
80
70
60
50
40
SO
20
10
.A ADAMS (4 SITES)
-A' ARAPAHOE (I SITE )
-B BOULDER (2 SITES)
-C CLEAR CREEK {I SITE )
-D DENVER (6 SITES)
-0' DOUGLAS ( I SITE )
-0 GILPIN { I SITE )
-J JEFFERSON (5 SITES)
1937
I960 1962 1964 1966 1968 1970 1972 1974
Figure 3. Trends in countywide annual geometric means of TSP
11
-------
4440-
4420-
4400-
4360
4360-
4340-
ARAPAHOE
4320-
I I I I I I I I I I
420 440 460 460 500 520 540 560 580 600
Figure 4. Annual geometric means of ISP in the Denver AQCR (yg/m )
-------
4388 -
4386 -
[490,4384]
KILOMETERS
492 494 496 498 900 902 904 906 908 910 912 914 916
[918,4384]
Q
Figure 5. Annual geometric means of TSP in the Denver county area (pg/nr)
-------
LARIMER
WELD
*
\
\
\
SAMPLING SITE
Figure 6. Average annual suspended particulate concentrations
measured in Denver and surrounding counties during
1970-1972. Units are yg/m3
14
-------
SECTION II
ANALYSES
This section presents the individual analyses that were performed on the
data gathered for the study of the particulate problem in Denver. It
attempts to correlate various factors which are known to influence air
quality with the measured ambient TSF concentrations. These factors in-
clude those that most often come under the jurisdiction of the air pol-
lution control agency - emissions, regulations, and monitor siting - and
other factors that are not usually or cannot be controlled - urban activ-
ity, meteorology, etc.
EMISSIONS
The Metropolitan Denver Intrastate AQCR is a relatively light industri-
alized area with less than 150 sources coded into the National Emissions
Data System (NEDS) for all eight counties. The current NEDS for the area
provides the breakdown of the emissions from each source category in the
AQCR and the individual counties given in Table 3. The majority of the
emissions in the AQCR (82 percent) occur in the three counties, Boulder,
Denver, and Jefferson, whereas the counties of Clear Creek, Douglas, and
Gilpin each contribute less than 2 percent to the total.
Though the point sources are not numerous, they do contribute slightly
over half of the total inventoried emissions in the AQCR. However, the
point sources do not contribute evenly to the emissions in each county.
While there are no point sources listed in Clear Creek County, its neigh-
boring county, Gilpin, has 98 percent of its particulates attributed to
15
-------
Table 3. PARTICULATE EMISSIONS IN THE DENVER AQCR, BY COUNTY (CURRENT NEDS (1974))
foal coatatla
eternal
CeildcotUl
electrical
loduatrial
C-I
Internal
laauatrlal praccoa
Chencal
food/airlcottnra
Hetele
Mineral
Petroleum
Otter
folld Wai to Uapooal
Cncrnacnt
laildential
C-t
iMMtrlal
Trenaportatloa
GaaollM
Dleiel
Aircraft
Veaaela
Taut
IOC COtM
Dearer M)Ct
Total aertaatime TPT
Point
(10.468)
- 10.468
_
8.721
1.170
178
.
(13.113)
.
248
1
13.409
132
24
(377)
_
.
177
.
_
.
-
-
X4.661
*«
Ana
(13.251)
13.151
411
.
12,206
637
.
-
-
-
.
.
.
.
(464)
.
120
111
12
0,119)
5.318
1.3(3
395
HUM
43.8
Total
(23.721)
23.721
411
8.721
13,576
1.013
-
13,815
-
248
1
13.409
112
24
(841)
_
120
308
11
(7.119)
3.338
1.385
193
43.497
loot
Man County
Total eojiMlpna TPT
Point
(801)
803
.
748
47
9
-
(1.548)
-
221
-
1,195
132
-
-
.
_
.
.
_
.
-
-
-
2.331
»
Area
(1.084)
1,084
56
.
943
M
-
-
-
-
-
-
-
-
(81)
-
61
17
2
(961)
735
208
-
1.119
47
Total
(1.887)
1,887
56
748
992
92
-
(1.548)
-
221
-
1,193
112
-
(12)
-
61
17
2
(961)
755
208
-
-
4.4(0
ion
Goaty I
of Aqa
Total
(0
8
14
9
7
9
-
(4)
-
89
-
9
100
-
(10)
-
20
1
17
(14)
14
13
-
10
-
Arapahoe Goaty
Total raleaLooo TPT
Point
(2)
2
-
-
2
-
-
(151)
-
-
-
151
-
-
-
-
.
-
.
-
-
-
-
~
131
71
Ana
(1,127)
1.1J7
42
-
1,010
55
-
-
-
-
-
-
-
-
(70)
-
51
14
2
(693)
714
181
-
1,091
93S
Total
(1.129)
1.129
42
-
1,032
35
-
(151)
-
-
-
151
-
-
(70)
-
S3
14
2
(193)
714
1(1
-
1.143
urn
of add.
Total
(5)
5
10
-
6
5
-
(1)
-
-
-
1
-
-
(1)
-
11
1
17
(13)
11
11
-
,
-
looMor Goaty
Total eaiaaiona TPT
Point
(8.481)
8.481
-
7.579
901
-
-
(2.127)
-
-
-
1.1"
-
-
-
-
-
-
-
-
~
10.413
n
Ana
(1.516)
1.518
56
-
1.381
84
-
-
-
-
-
-
-
-
(88)
~
43
44
1
(700)
352
147
1.306
11
Total
(9.999)
9.999
56
7.579
2,284
84
-
(1.117)
-
-
-
2.127
-
-
(88)
~
41
44
1
(700)
512
1*7
~
I
U.911
ion
Goaty I
of Aqa
Total
(42)
42
14
67
17
-
(13)
-
-
14
-
-
(10)
13
9
(10)
10
11
"
a
-
-------
Table 3 (continued). PARTICULATE EMISSIONS IN THE DENVER AQCR, BY COUNTY (CURRENT NEDS (1974))
fbel unbutton
tatemal
Residential
Electrical
Industrial
C-X
latenal
foduitrlal proceaa
Chemicil
rood/igrlcaltnral
Iktali
Mlneril
fatroleuB
Other
Soil* vote dliDoeal
Con moot
Inldentlal
C-X
Industrial
Transportation
CaMlInt
Dleiel
Aircraft
fault
macallancoM
total
Sol notified
dear Crark County
otal eBliiiooa TIT
Feint
»
.
_
.
-
.
-
-
_
.
-
-
.
-
_
_
_
.
.
-
-
-
.
-
Ana
(16)
16
6
.
_
*
.
.
-
.
.
-
-
.
(1)
.
1
.
_
(44)
41
4
-
-
-
61
160
total
(16)
16
6
.
_
9
..
.
-
-
.
-
-
.
(1)
-
1
_
.
(44)
41
4
-
-
-
61
ion
County X
of tCf*
Total
.
_
1
_
.
1
.
-
-
-
.
-
-
.
.
.
_
(1)
1
-
-
-
.
-
term Canary
Total minions TPT
Feint
(4il)
411
.
394
12
41
.
(1.901)
-
27
-
1.850
-
24
(19)
-
.
19
_
.
-
_
-
-
-
2.411
23
Area
(7.160)
7,160
173
-
6.669
316
-
-
-
-
-
-
-
-
(119)
-
81
14
4
(3.018)
2.113
371
367
-
-
10.336
67
Total
(7.611)
7.611
173
394
6.681
363
-
(1.901)
-
27
-
1.610
-
24
(178)
-
81
91
4
(1.018)
2.113
17!
367
-
-
12.747
ion
County Z
ef UtOL
Total
(12)
12
42
3
49
36
-
(14)
-
11
-
14
-
100
(21)
-
25
18
33
(41)
40
42
93
-
-
H
-
Doutlaa tatty
'otal ealaiiom TPT
PoUt
(116)
116
-
-
136
-
-
(23)
-
-
-
23
-
-
-
-
-
-
.
-
.
-
179
74
Area
(15)
»
1
-
14
11
-
-
-
-
-
-
-
-
(4)
-
1
1
-
(71)
66
9
-
~
134
K
total
(411)
411
1
-.
190
IS
-
(21)
-
-
-
21
"
-
(4)
-
1
1
-
(73)
66
9
-
~
~
112
ion
County X
of AQCI
total
(2)
2
1
-
3
1
-
-
-
-
-
-
1
-
(1)
1
1
-
"
1
-
Cllata Cootty
total emUilona TPT
roint
.
-
-
-
-
-
-
(862)
~
-
-
862
-
-
-
-
-
-
-
-
-
m
m
661
90
Area
(1)
1
-
-
-
1
-
-
-
-
-
~
-
-
~
-
-
-
(11)
14
1
-
"
"
It
S
total
(1)
1
-
-
-
1
(662)
~
-
-
862
-
-
-
-
(11)
14
1
-
"
678
ion
County Z
of AQOt
total
»
m
-
-
-
-
(6)
-
-
6
-
-
-
-
2
Jeffenon Cooaty
Total enliiloni TPT
Peint
(171)
171
-
- .
30
321
-
7.202)
~
-
1
7,201
O19)
-
319
-
-
-
"
"
7.696
67
Area
(2,292)
1.292
73
-
2.147
71
-
-
-
~
(100)
"
76
21
3
(1.369)
1.081
260
28
3.761
13
roint
(2.667)
2.667
73
-
2.197
397
(7.202)
"
"
1
7,201
~
(419)
~
76
340
3
(1.36M
1.081
260
28
11.637
ion
County I
ef AQCa
Total
(11)
11
16
-
16
39
(32)
~
100
M
"
"
(30)
24
67
33
(19)
20
19
7
M
*
-------
point sources. Even in those counties with more emissions - Denver and
Boulder - the contribution varies widely with 23 percent and 82 percent,
respectively, coming from point sources.
Emission Density
Due to its small size (201 km2) Denver County has a much higher density
of emissions than the other counties in the area even though it has only
28 percent of the total emissions. (Boulder has the same level of total
emissions but almost 10 times as much area.) In addition, much of the
emissions in the surrounding counties are concentrated near Denver
County. Figures / and 8 provide emission density isopleths for
area and point sources in the AQCR, respectively. The allocated emissions
for these figures are the result of a Computer Assisted Area Source Emis-
sions (CAASE) gridding procedure performed for the development of an ex-
ample maintenance plan for the Denver area utilizing the NEDS inventory
at that time. As the immediate Denver County area is the area of highest
emission density and similarly highest TSP concentrations, Figures 9
and 10 provide a better resolution of the emission density of area and
point sources. (The less than whole numbers in the outlying counties in
these figures are a result of different coordinates being used.)
An updated emission inventory of all point sources is just being com-
pleted for Colorado by PEDCo Environmental as part of the future main-
tenance planning activities in the state. As discussed later, this
update has provided significantly different emission totals for many
of the counties in the AQCR. A point source listing with emission rates
was provided to GCA from this effort and the locations of all of these
sources in the Denver area are given in Figure 11 and for the rest
of the AQCR all sources over 10 tons per year are plotted in Figure
12. From all of these figures it is evident that the Denver County
area is the most densely polluted part of the AQCR with major point
source activity on the western, southern, and northern boundaries of
the county.
18
-------
4440
4420-
4400
4380
4360-
4340-
DENVER
ARAPAHOE
4i>20-
I
.20
I
440
I
460
I
480
I
500
I
520
I
540
I
560
I
580
I
600
*
Figure 7. Area source emission density in the Denver AQCR (x 10 tons per year per 16 sq km)
(Based on CAASE program - NEDS Circa 1973)
-------
N)
O
4440
4420
4400-
4380
4360-
4340-
4320-
I
420
I
440
ARAPAHOE
I
460
I
480
I I I I I I
500 520 540 560 580 600
Figure 8. Point source emission density in the Denver AQCR (x 10 tons per year per 16 sq km)
(Based on CAASE program - NEDS Circa 1973)
-------
[490,4384]
KILOMETERS
492 494 496 498 500 30? 504 506 508 510 512 514 516
[518,4384]
Figure 9. Area source emission density in the Denver County area (x 10 tons per year per 16 sq km)
(Based on CAASE program - NEDS Circa 1973)
-------
ISJ
INJ
4386 -
[490,4384]
KILOMETERS
492 494 496 498 500 902 904 906 908 910 912 914 916
[918,4384]
Figure 10. Point source emission density in the Denver County area (x 10 tons per year per 4 sq km)
(Based on CAASE program - NEDS Circa 1973)
-------
ro
U)
KEY:
D<25 TPY
0 25-IOOTPY
BIOO-50OTPY
B5OO-IOOO TPY
>IOOO TPY
492 494 496 498 500 SO2 504 5O6 508 510 512 514 516
518,4984
Figure 11. Location of point sources in the Denver County area
(Based on recent PEDCo update)
-------
4440
4420
4400-
4380
4360-
4340
DENVER
ARAPAHOE
KEY =
O<25 TRY
025- 100 TRY
H IOO-5OO TPY
B 500 -1000 TPY
> IOOO TPY
4320-
I
420
44O
1
460
\
480
500
\
520
1
540
560
1
580
600
Figure 12. Location of point sources (_>_ 10 tons/year) in the Denver AQCR outside of the Denver County area
(Based on recent PEDCo update)
-------
The above NEDS data does not include any estimate of the possible fugi-
tive dust emissions that may be occurring in the AQCR. Fugitive dust
sources have been considered to contribute significantly to the TSP
concentration and several estimates of their possible impact have been
made. A calculation of the preliminary data supplied from the MRI
2
study of dirt roads, dirt airstrips, construction, and agricultural
tilling indicated that the fugitive dust emissions from these source
categories contributes almost 10 times the tonnage as the total inven-
toried emissions and over 20 times the tonnage of the inventoried area
source emissions for the AQCR (see Table 4). The majority of these emis-
sions are from dirt roads (64 percent) and construction (31 percent).
Another study, specific to the State of Colorado, was performed by FEDCo
Environmental to establish the levels of fugitive dust. The results of
this study, given in Table 5, indicate emissions amounting to more than
two and a half times the NEDS emissions. While the accuracy of these
emission inventories can not be fully determined in this project, it is
assumed that the latter study would be more applicable to the Denver area
than the MRI study which indicates more than three times as much fugitive
dust as the PEDCo report. The allocation of the fugitive dust emissions
to different areas in the counties to determine emission densities, as
done for the Denver maintenance study, is given in Figure 13.
From these figures some estimate of the density of the emissions in the
vicinity of each sampler may be determined. Table 6 provides a listing
of the monitors in order of increasing TSP concentration and with the
estimated emission densities from each source sector (point, area, fugi-
tive). Since the emission densities are from 1972 and 1973 inventories,
the TSP concentration used in the table is the geometric mean of the 1972
and 1973 annual geometric means for each station. The point and area
source emission densities are an average of the respective emission
densities within a 2 kilometer radius of the monitor.
25
-------
Table 4. FUGITIVE MISSIONS IN THE METROPOLITAN DENVER AQCR (IN TONS PER YEAR)'
County
Adams
Arapahoe
Boulder
Clear Creek
Denver
Douglas
Gllpin
Jefferson
AQCR total
Percent of total
Unpaved
roads
56,000
26,000
83,000
17,000
1,270
40,000
5,000
44,000
272,270
64
Dirt
air
strips
5
184
0
0
0
88
0
0
277
0
Construction
22,000
16,000
12,000
1,460
46,000
1,640
320
30,000
129,420
31
Land tilling
16,000
5,000
1,280
0
0
610
0
370
23,260
5
Total
94,005
47,184
96,280
18,460
47,270
42,338
5,320
74,370
425,227
100%
County %
of AQCR
22
11
23
4
11
10
1
17
100%
N3
a 2
dfrom MRI study
Not included in any other inventory.
-------
CO
vl
Table 5. DENVER AQCR FUGITIVE DUST INVENTORY3
Fugitive duat sources
Unpaved roads
Sand on paved roads
(snow control)
Agriculture
Land development
Adam
12,704
1,979
6,358
240
Arapahoe
8,205
1,307
821
975
Residential and '
commercial construction
Hlgbway construction
Quarrying, mining, and tailings
Aggregate storage
Cattle feedlota
Total fugitive dust
County H of AQCH
2,883
1,266
320
164
144
26,058
22
3,005
359
416
24
Neg.
15,112
13
Boulder
10.403
555
6,586
278
285
490
1,351
124
105
20,177
17
Clear Creek
987
Neg.
Meg.
20
1,920
3,091
1,419
Neg.
Neg.
7,437
6
Denver
674
5,816
Neg.
Neg.
944
524
Neg.
80
Neg.
8,038
7
Douglas
1.537
Neg.
560
2,595
563
Neg.
328
4
22
5,629
5
Gllpln
17,732
Neg.
Neg.
3
480
Neg.
11
2
Neg.
18,228
15
Jefferson
7,470
2,581
328
473
3.235
2,648
1,056
11
Neg.
17,802
15
Total
59.712
12,238
14.673
4,584
13.315
8.378
4.901
409
271
118.481
1001
I
50
10
12
4
11
7
4
0
0
100Z
From PEDCo data.3
Done concurrent with PEDCo 1972 Inventory.
Hot Included with area sources In Table 7.
-------
to
03
4440
4420-
4400-
4380
4360-
4340-
3B
33 i
25
29
LEGEND-
COUNTY LINE
ZONE BOUNDARY
4320-
I I I I I I I I I I
420 440 460 460 500 520 540 560 580 600
Figure 13. Fugitive dust emission density in the Denver AQCR (tons per year per 4 sq km)
(PEDCo 1972 study. Allocated by GCA in Maintenance Study)
-------
Table 6. PARTICULATE EMISSION DENSITIES AND TSP CONCENTRATIONS (1972-1973)
AT MONITORING SITES IN THE DENVER AQCR
Station
Rocky Flats
Cherry Creek
Golden
Boulder
State Health
Black Hawk
Lakewood
Castle Rock
Hull Photo
Westminster
CARIH
Aurora
Edgewater
Brighton
Adams City
Englewood
Arvada
Longmont
Sewer Plant
Sch. Adm. Bldg.
Gates Bldg.
TSP3
concentration
41
45
65
66
68
70
73
74
77
80
83
91
92
96
96
106
109
111
120
126
127
Emission density
Pointb 100
tons /year
per 4 sq km
0
0
1.25
0
0
0
0
0
0
0
0.25
0
4
1
2
0
0
1
3
0.75
4
Pointb 100
tons /year
per 4 sq km
0
0
0
1.25
1.75
0
0.75
0
1.25
0.75
1.75
0.5
1.0
0
0.5
0.75
0.25
0.5
0.25
1.75
1.5
Fugitive
tons/year
per 4 sq km
31
28
31
28
160
30
74
10
160
38
160
74
38
38
28
74
84
160
160
160
160
Total
tons/
year
31
28
156
153
335
30
149
10
285
113
360
88
574
138
288
103
99
234
485
410
710
Geometric mean of 1972 and 1973 annual geometric means.
Sources: Point - CAASE
Area - CAASE
Fugitive - PEDCo 1972
29
-------
With several exceptions, the data in this table indicates that the
TSP concentration Is generally responsive to the total emission
density.
The major exceptions to the trend in rising concentration with increas-
ing emission density are in Denver County (State Health, Hull Photo,
CARIH) due to the large density of fugitive emissions and at the
Edgewater monitor due to impact of point sources. While the latter
case may be due to the positioning of the monitor relative to the
sources and also specific errors in the point source emission inventory,
the fact that the air quality measured in Denver County does not reflect
the emission density due to fugitive sources brings into question the
relevance of this inventory. As most of the Denver fugitive emissions
are a result of sanding on paved roads, this problem is evaluated
further under the discussion of sanding for snow control.
In addition to differences in monitor siting and problems with emission
inventories, variations in this table also reflect the topography and
air flow in the area. Due to the strong valley effect, monitors which
are located in a relatively low emission density area in the valley will
often be measuring participates generated in another part of the valley.
This is discussed further under the analysis of the climatology.
Emission Trends
A major problem in the formulation of control strategies In the Denver
AQCR has been the determination of an appropriate emission inventory
upon which to base the strategies. While the exclusion of the consider-
ation of fugitive dust in the Colorado SIP6 is a large element in this,
the more conventional point and area source inventory in the area has
never been completely defined.
30
-------
Table 7 presents summaries of the point, area, and total emissions for
each county in the Denver AQCR as determined from compiled and updated
emission inventories from the time of the SIP to the present. The
data in this table represents the point and area source emission
estimates used in the Colorado SIP for the original formulation of
attainment strategies, in the PEDCo study of fugitive dust for the
determination of possible measures for the attainment of the secondary
standard for particulates, in the GCA formulation of an example main-
tenance plan for the Denver area^ (data from 1974 NEDS printout), the
current NEDS (1975 printout) provided for this study, and recent
7 8
updates of the area and point source inventories to be used for main-
tenance planning by the state. If these were comparable emission in-
ventories, the fact that they each represent different time periods would
imply a steady progression to the emission levels projected under the
controls of the SIP. Instead, these inventories indicate the widely
varied data used for strategy planning which is reflected in the success
of the strategies.
As no comparable information was available on long term emission trends
for correlation with air quality, the modeling and projection of emis-
sions and air quality that was done for the development of an example
maintenance plan in Denver was reviewed. The work done under this study
included the modeling of the point, area, and fugitive source emissions
using 1972 emissions, the projection of the various source categories
in each county based on the regulations for the State of Colorado and
the growth rates over this time, and the determination of the impact
on air quality of the projected emissions.
In the development of the example plan, it was determined that the regu-
lations imposed by the State of Colorado would have significant impact
on the point source emissions and thereby on the levels of TSP contributed
by point sources. Table 8 provides particulate concentrations cal-
culated by applying the Climatological Dispersion Model to point source
31
-------
Table 7. DIFFERENCES IN POINT AND AREA SOURCE EMISSION INVENTORIES OF
PAKTICULATES IN THE DENVER AQCR 1970-1975
AQCR
14,459
42.720
25,856
24.601
12.982
5.581
8.963
8,739
13,457
20.836
9.000
5,594
23.422
51,459
99,312
49.497
21.982
11.445
Jefferson
152
8.652
7,917
7,896
2,280
152
1,018
1,017
2.205
3,761
1.000
641
1.170
9,669
10,123
11.657
8.296
793
Cllpln
0
2,640
862
862
0
0
4
9
4
16
-
1
9
649
865
818
12,280
1
Douglas
71
44
379
379
31
71
52
52
72
134
100
44
123
1,496
451
512
151
115
Denver
2,141
1,117
2,451
2.411
1.171
1.431
4,065
3,887
7,186
10,326
4,100
2,646
6.206
5,004
9,636
12,747
5,271
4,077
Clear
Creek
0
.
.
0
8
0
39
39
43
61
.
5
39
39
43
61
8
5
Boulder
1,777
7.882
9.937
10.615
3,283
936
795
763
1,457
2,306
800
460
2,572
8.645
11,394
12.921
4,083
1,396
Arapahoe
0
8,537
154
153
3,374
0
863
863
1,224
2,092
900
594
863
9,400
1,378
2,245
A, 274
594
Adams
10.318
12.448
3,481
2,352
2.815
3.261
2.122
2,109
1.265
2,129
2,100
1.203
12,440
14.557
4.746
4.480
4,915
4,464
SIP
(1970)6
PEDCo
Study
(1972) 3
Example
AQMPI
(1973)
Current
NEDS
(1974)
FEDCo
Update
(1975)
SIP
Projected8
SIP
(1970)6
PEDCo
Study
(1972)
Example
AQMP*
(1973)
Current
NEDS
(1974)
TRW
Update
( 973)
SIP
Projected'
SIP
(1970)»
PEDC
Study
(1972)
Example
AQMP1
(1973)
Current
NEDS
(1974)
Recent
Update5
(1974)
SIP
Projected8
Given In the SIP at the projected emissions under the controls stipulated In the SIP.
bTho recent update Is considered 1974 due. to Its combination of 1973 and 1975 Inventories.
32
-------
Table 8. CALCULATED PARTICULATE CONCENTRATIONS DUE TO POINT
SOURCES3 - 1972 AND 1975b (yg/m3)
County
Adams
Arapahoe
Boulder
Clear Creek
Denver
Douglas
Gilpin
Jefferson
Location
Westminster
Aurora
Brighton
Adams City
Cherry Creek Dam
Englewood
Boulder
Longmont
Idaho Springs
State Health Department
Hull Photo
CARIH
Sewer Plant
Sch. Admin. Bldg. (State)
Gates Building
Castle Rock
Black Hawk
Rocky Flats
Golden
Lakewood
Edgewater
Arvada
Concentration
1972
9
3
7
17
2
8
1
2
1
5
6
12
14
22
22
1
1
4
5
9
56
6
1975b
1
1
3
8
0
1
0
1
0
1
2
2
6
4
3
0
0
2
2
1
4
1
% reduction
89
67
57
53
100
88
100
50
100
80
67
83
57
82
86
100
100
50
60
89
93
83
Calculated with the Climatological Dispersion Model.
1972 NEDS data with Colorado regulations applied to all point sources
over 100 tons/year.
33
-------
emissions in 1972 and 1975. The 1975 emission levels were determined by
applying the Colorado regulations to all NEDS sources greater than 100
tons/year. The concentrations are for the specific monitoring sites
in the AQCR. Reductions in the concentration attributable to point
sources ranged from 50 to 100 percent at the different sites with
countywide average reductions around 70 percent or greater.
Because of the large contributions from area and fugitive sources, when
these emissions were included in the modeling effort (using the Hanna-
Gifford Area Source Model) , the improvement in the air quality was much
less than that due only to point sources. At the same time, since area
source emissions were increasing with the growing population and fugitive
source emissions could not be controlled to the same extent as point
sources, the importance of these sources was projected to increase
between 1972 and 1975. Table 9 presents the results of the modeling
of all three source sectors. It includes the calculated concentration,
adjusted for background, at each of the monitoring sites in 1972 and
1975 and the percent contribution of each of the source sectors to the
above background concentration. The contribution of point sources to
the modeled TSP concentration was projected to decrease significantly
between 1972 and 1975 while the percent contribution from the area and
fugitive source categories would rise. Area sources show the biggest
rise as these emissions are increasing with the growth of the area
while the fugitive dust sources are being controlled by the fugitive
dust regulations. The projected decrease in above background TSP
concentration between 1972 and 1974 varies between 0 and 56 percent
with Denver County having 10 to 20 percent reductions.
While Table 9 indicates that those monitors which were most influenced
by point sources in 1972 generally are expected to show the greatest
improvement by 1975, the trends in air quality to date do not parallel
these results. Table 10 allows for a comparison between the ratio
of modeled TSP concentration (above background levels) in 1972 and 1975
34
-------
Table 9. PERCENTAGE CONTRIBUTION OF PARTICULATE SOURCE SECTORS IN THE DENVER AQCR (1972 AND 1975)
OJ
County
Adams
Arapahoe
Boulder
Clear Creek
Denver
Douglas
Gilpln
Jefferson
Location
Westminster
Aurora
Brighton
Adams City
Cherry Creek Daa
Englevood
Boulder
Longmont
Idaho Springs
State Health Dept.
Hull Photo
CARIH
Sever Plant
Sch. Admin. Bldg. (State)
Gates Building
Castle Rock
Black Hawk
Rocky Flats
Golden
Lakevood
Edgevater
Arvada
1972d
Z contribution
Point
19
IS
29
39
15
20
2
4
8
6
7
10
18
19
21
17
1
25
29
26
54
14
Area
45
-
-
22
_
53
79
38
-
26
34
40
13
35
29
-
-
_
-
-
20
24
Fug.
36
85
71
39
85
27
19
58
92
68
59
50
69
46
50
83
99
75
71
74
25
62
Adj. AQb
70
47
51
68
41
64
75
77
41
98
108
122
97
131
122
35
98
44
45
60
118
66
1975«
Z contribution
Point
3
6
12
19
_
3
_
2
-
1
2
2
8
4
3
-
-
12
11
4
4
3
Area
60
-
-
35
_
71
87
44
-
32
40
47
17
47
40
-
-
_
-
-
48
33
Fug.
37
94
88
46
100
26
13
54
100
67
58
51
75
49
57
100
100
88
89
96
48
64
Adj. A0>
63
43
45
57
37
58
75
75
39
92
101
110
85
114
102
34
97
37
38
50
69
59
Z reduction
In TSP
concentration0
18
24
29
29
36
18
0
4
18
9
9
13
18
17
22
20
1
50
47
33
56
19
aEmission rates determined by assuming all sources under compliance and appropriate growth rates in activity.
Adj. AQ is the fitted TSP Concentration adjusted for background contribution in ug/m^.
Assuming a background of 30 yg/m^.
Based on Circa 1973 NEDS Printout (assumed 1972 data).
-------
Table 10. COMPARISON OF ACTUAL AND PROJECTED CHANGES IN TSP
CONCENTRATIONS IN THE DENVER AQCR
Monitor
School Administration
Edge water
Gates Building
Westminster
Longmont
Hull Photo
Arvada
Aurora
Boulder
Englewood
Brighton
CARIH
Golden
Idaho Springs
Lake wood
Castle Rock
Sewer Plant
State Health
Adams City
Rocky Flats
Ratio of actual annual
geometric means,
1972 to 1972
0.79
0.90
0.94
0.94
0.97
0.98
1.00
1.00
1.06
1.07
1.11
1.17
1.19
1.19
1.22
1.28
1.29
1.29
1.46
1.88
Ratio of projected
annual geometric means3
1974 to 1972
0.83
0.44
0.78
0.82
0.96
0.91
0.81
0.76
1.00
0.82
0.71
0.87
0.53
0.82
0.67
0.80
0.82
0.91
0.71
0.50
1From example maintenance plan for Denver.
36
-------
and the similar ratio for actual measured concentration in 1972 and
1974. This table has been arranged to present the monitors in order
of decreasing actual improvement in air quality (increasing ratio) to
provide some understanding of what has occurred since the time of the
SIP. The order of the monitors in Table 10 indicates that no pattern
of trends is evident during this short time frame. While about half
of the monitors in Denver have shown some decreases in TSP concentration
(School Administration, Gates Building, Hull Photo), the other monitors
(CARIH, Sewer Plant, State Health) have all noted increases in TSP levels
between 1972 and 1974; similar differences may be noted in the other
counties. In general, more monitors showed increasing values in TSP
than decreasing values.
In addition to the review of long-term trends in emissions and TSP
concentrations, some further understanding of the relationship between
these two parameters may be derived from an analysis of the seasonal
fluctuations. In Denver, the seasonal differences in emissions would
be due not only to the space heating emissions that occur in the winter
but also to the fugitive emissions from the street sanding in winter and
the construction activity primarily in the summer. Table 11 presents
these emissions apportioned to each month. The space heating emissions,
estimated to be equal to the sum of the current NEDS area source
emissions from residential and commercial/institutional use and one-third
of the industrial area source emissions (a similar ratio as found in
Philadelphia), are apportioned by heating degree days for 1974. The
fugitive emissions from sanding on paved roads were apportioned by the
amount of cubic yards of sand used each month and the construction
activity emissions were evenly divided among those months when no sanding
activity occurred as it was expected that little ground breaking activity
would occur during snow cover.
From the estimated monthly emissions in Table 11 it would appear that
in Denver County there are two to three times the emissions in the winter
37
-------
Table 11. ESTIMATED MONTHLY EMISSIONS OF PARTICUIATES IN
DENVER COUNTYa
Month
January
February
March
April
May
June
July
August
September
October
November
December
Total
Space
heating
emissions
597
380
299
244
54
27
0
0
81
163
380
489
2,714
Emissions
from ,
sanding
2,153
1,403
535
241
0
0
0
0
0
0
589
895
5,816
Emissions
from
construction
0
0
0
0
244
245
245
245
245
244
0
0
1,468
Total monthly
emissions
3,649
2,682
1,733
1,384
1,197
1,171
1,144
1,144
1,225
1,306
1,868
2,283
20,786
Ratio0
2.11
1.55
1.00
0.80
0.69
0.68
0.66
0.66
0.71
0.75
1.08
1.32
Based on space heating emissions from current NEDS and sanding and con-
struction emissions from PEDCo 1972.
The annual emissions from sanding were apportioned relative to the
monthly variations in sand used for snow control.
CMonthly emissions + average monthly emissions.
38
-------
months than in the summer months due to space heating and fugitive
emissions from sanding activities. If this is the case, it would be
expected that the TSP levels above background would be similarly higher
in the winter months, assuming comparable meteorology. Figure 14
provides a plot of the ratio of the monthly emissions to the average
monthly emissions and also the ratio of the above background levels of
the county-wide monthly geometric means to the county-wide annual
geometric mean. This figure indicates a fairly good correlation between
the seasonal trends in emissions and TSP concentration given the assump-
tions about emissions stated above. Discrepancies in the trends, espe-
cially during May, are partially explanable through the analysis of
meteorology given later. The emission ratios are fairly sensitive to
the emission inventory inputs and, while the general shape of the graph
remains the same, the magnitude of the difference between the seasons
varies widely with the inputs. For example, if it is assumed that the
emissions from sanding are half of those assumed by PEDCo, the extremes
of the ratios - summer and winter - are much closer to the above back-
ground ratios of TSP levels; i.e. emission ratios ranging from 0.77 to
1.85 corresponding to TSP ratios of 0.80 and 1.95 for July and January
respectively.
LEGAL AUTHORITY, REGULATIONS, AND SURVEILLANCE
The Colorado Air Pollution Control Act of 1970 created the nine-member
Colorado Air Pollution Control Commission to develop an air pollution
control program and promulgate such regulations as may be necessary or
desirable to "achieve the maximum practical degree of air purity in every
portion of the state." Eight members of the Commission are appointed by
the governor with the consent of the Senate for a term of 3 years and
the other member is from the State Board of Health.
The duties of the Air Pollution Control Commission include the develop-
ment and maintenance of a comprehensive program for prevention, control,
39
-------
2.2
2.0
1.8
1.6
1.4
1.2
I"
* 0.8
0.6
0.4
0.2
EMISSIONS
JFMAMJJASOND
MONTH
Figure 14. Monthly emission and above background TSP ratios in Denver (1974)
40
-------
and abatement of air pollution throughout the entire state, Including a
program for control of emissions from all significant sources of air pol-
lution; the promulgation of ambient air goals for every portion of the
state; the adoption and promulgation of ambient air quality standards and
emission control regulations; the receipt and, at Its discretion, the
hearing and determination of violations and applications for the granting
of variances; and, at its discretion, the review of any variance order or
determination of the variance board to which such applications may have
been transmitted.
The Colorado Air Pollution Control Act of 1970 also established a division
within the Department of Health to administer and enforce the air pollu-
tion control programs adopted by the Commission. Specifically, the Divi-
sion is empowered to conduct studies and research with respect to air
pollution, Including the control, abatement, or prevention thereof; de-
termine if the ambient air standards are being violated in any area of
the state; enter and inspect any property, premise, or place for the
purpose of investigating any actual, suspected, or potential source of
air pollution; furnish technical advice and services; notify any affected
Jurisdiction of standards which are not being met; and to issue contami-
nant emission notices. The Division also has the authority to enforce
compliance with the promulgated emission control regulations.
The Department of Health, within which the Air Pollution Control Division
was established, is designated as the "state agency" for all purposes of
the Federal Clean Air Act, as amended, and regulations promulgated under
that act. The Department of Health accepts and supervises the adminis-
tration of loans and grants from the Federal government (and from other
sources, public or private) which are received by the state for air
pollution control purposes.
As required by Section 66-31-8 of the Colorado Air Pollution Control Act
of 1970, the Colorado Air Pollution Control Commission has adopted a
41
-------
number of regulations which stipulate control measures for emissions and
other measures which help provide for the attainment of the NAAQS. In
addition, the Commission has also adopted ambient air standards for
suspended particulate matter and sulfur dioxide for the Metropolitan
Denver AQCR and the State of Colorado which are more stringent than
those promulgated by EPA. The standards for particulate matter outside
of the Denver AQCR and other designated areas is 150 yg/m on a 24-hour
basis and 45 yg/m for the annual arithmetic average. These standards
are also to be attained in the Denver AQCR by 1980 with intermediate
3 3
short-term and long-term standards of 200 yg/m and 70 yg/m in 1973
3 3
and 180 yg/m and 55 yg/m in 1976.
The regulations on emissions of contaminants to the air vary as to their
level of technicality. The control stipulations range from banning of
emissions (e.g., open burning) and opacity to process rates. Some of the
regulations apply generally to control of specific pollutants (particu-
lates, sulfur oxides, odor, hydrocarbons, and chemical substances) from
many sources while other apply to individual processes (wigwam waste
burners, alfalfa dehydration plants, new sources as controlled by New
Source Performance Standards, and motor vehicles). In addition, a per-
mit system, requiring a permit to construct and operate, exists.
The basic control of particulates is through Regulation 1 from which the
summary for each source type is given below.
Visible Emissions - The emission from stationary sources
of any pollutant in excess of 20 percent opacity is for-
bidden. From mobile sources, this section prohibits the
emission of any visible emissions for more than 5 seconds
from any four-cycle gasoline vehicles, of any emissions
greater than 20 percent opacity for more than 10 seconds
from a two-cycle gasoline vehicle, and of any emissions
greater than 30 percent opacity at less that 8,000 feet
or 40 percent opacity at more than 8,000 feet for more
than 10 seconds for diesel-powered vehicles.
42
-------
Open Burning - Open burning is allowed by permit only,
contingent on location, potential contribution to air
pollution, climatic conditions, and the existence of
alternative disposal methods.
Fuel Burning Equipment - The emissions from fuel burn-
ing are limited to a maximum of 0.5 pounds per million
Btu for sources generating less than 1 million Btu, and
0.10 pounds per million Btu input for units larger than
500 million Btu. Intermediate values can be determined
from the graph in Figure 15.
Incinerators - All incinerators in the state must not
emit more than 0.15 grains per standard cubic foot and
in designated areas of the state, including the Denver
AQCR, a limit of 0.10 grains per standard cubic foot
is set for all new incinerators and also for existing
incinerators effective 1977. In addition, in the desig-
nated control areas of the state, incinerators on prop-
erty devoted to residential use are prohibited effective
1977. Permits are required for all incinerators.
Manufacturing Processes - Maximum hourly emission rates
from any process are determined by the graph in Figure 16
Each process unit is considered a separate entity regard-
less of how many units are vented through the same opening.
Fugitive Dust - The regulation of fugitive dust includes
a general statewide requirement that no fugitive dust be
emitted which exceeds 20 percent visible opacity or which
is visible after it leaves the property of the owner of
the emission source. Certain activities, such as agri-
culture, are exempted. Within the Priority I portions
of Air Quality Control Regions only, which includes the
Metropolitan area but not the whole AQCR, specific re-
quirements are established for control of dust from:
a. All new unpaved roads and parking areas with
traffic volumes of 165 vehicles per day (vpd)
or more.
b. Existing privately owned roads and parking areas
with 165 vpd or more.
c. Existing publicly owned roads and parking areas
with 165 vpd or more, but with controls only to
the extent allowed by financial resources.
d. Land development, construction, demolition, and
related activities.
-------
10
"o
V>
to
u
fe
u
I I I I I I I
I i i ill
I 1 I 11411!
I I I I I I I I
I I I I I 11
I I I I I I I ll I I I I I I II I I I I I I I I I I
I I I I I I
I
10
100
1000
10,000 IOO.OOC
FUEL INPUT RATE, 10 Btu/hr
Figure 15. Fuel combustion - emission rate curve for Colorado
-------
10* c-
en
o
5
to
uj
u
IE
10"
10-'
10
11111
i i t i in
i i ii t in
11 in
I02
10s 10 * 10*
PROCESS WEIGHT RATE, Ib/hr
10'
t I t I I III
IOT
Figure 16. Process weight rate curve for Colorado
-------
In addition, there are control requirements, statewide, on open
mining activities. Wherever requirements for controls are pro-
vided, permits must be obtained and specified types of abate-
ment and preventive measures identified in the permit must be
utilized.
In addition to the control program operated by the State, the City and
County of Denver maintains an Air Pollution Control Section in its Depart-
ment of Health and Hospitals: Environmental Health Service. Control
measures required by the City are essentially identical to those of the
State except for incinerators. The City has the additional restriction
that incinerators must be multiple chamber or auxiliary fuel-fired and
that all incinerators with a changing rate of more than 200 pounds of
solid waste per hour must not emit particulate matter in excess of 0.10
grains per standard cubic foot.
The particulate regulations in the Denver AQCR are among the most stringent
of those cities reviewed in the course of this study and as compared with
published summaries of other states. While Colorado's control of large
fuel-burning sources (greater than 500 x 10 Btu) is no more stringent
than the most stringent of the other cities (with the exception of
Washington, D.C.), it is much more restrictive than most of the cities
for the smaller sources and imposes the maximum control of 0.1 pounds/
10 Btu/hr on sources an order of magnitude smaller than in most other
areas. Similarly with incinerators, when considering the controls im-
posed by the City, the restrictions are on sources an order of magnitude
smaller than in many other areas. The general process weight rate regu-
lation is more stringent than those in other areas reviewed (with the
exception of Illinois) and slightly more stringent than the average of
all state regulations applicable to general process sources.
The regulation promulgated for the control' of fugitive dust, which be-
came effective August 1, 1974, is the most comprehensive and detailed of
those reviewed to-date. The controls under this regulation were the
3
maximum feasible controls recommended for the area in a separate study
46
-------
except for the lack of a control strategy for removing sand after sanding
operations due to snow and the control of dust from cattle feedlots.
While the control of this latter source was determined to be of little
significance, the removal of sand on paved roads was projected to help
prevent the future growth in fugitive dust emissions.
The enforcement of regulations is undertaken by both the Colorado Air
Pollution Control Division (CAPCD) and the Denver Air Pollution Control
Section with the latter agency working only within the City limits.
Almost all sources have been determined to be in final compliance with
the regulations with only one major source, a unit of the power company,
being out of compliance frequently due to operating difficulties. This
is expected to be solved shortly. Determination of compliance and en-
forcement relies primarily on the opacity regulation though sources also
must meet the other standards. Many sources have done actual stack sam-
pling either on their own or at the request of the CAPCD and, if com-
pliance is questionable, testing may be required. A reduction of 90
percent in point source emissions due to the regulations was estimated.
The fugitive dust regulation is too recently promulgated, to make an eva-
luation as to its enforcement or effectiveness. The CAPCD is just be-
ginning to have the ability to do the necessary vehicle counts and is
informing the various political subdivisions what needs to be done. The
requirement for a permit for construction and demolition activity and
the requisite controls, are apparently being accepted. Even though prior
to this thus, only minimal control was exercised.
The Air Pollution Control Section in the Department of Health and Hospitals
has undertaken an active program to control smoking vehicles and has a
visible emissions testing program to inspect the cars. Owners of cars
on the road found not to be in compliance are normally mailed a notice
of violation and are requested to comply with the law. If two sitings
are made for the same car, the owner may be called into court to determine
why compliance was not met. In April of 1975, the police became part of
47
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the program increasing the number of sitings almost threefold. In June
1975, there were almost 1000 vehicle emission sitings, 84 cars tested at
the inspection station with 11 of them failing, and 5 owners ordered to
comply by the court.
In reviewing the control programs in the Denver AQCR, it was felt that
Insufficient information was available for an accurate determination of
their effectiveness. The regulations are reasonably stringent but the
surveillance of the sources does not appear strict. Much appears to
rely upon the Air Contaminant Emission Notices that are filed by the
sources and many of these are several years old, some as old as 5 years.
If stationary soir.ces are actually in compliance, than the relative
importance of fugitive emissions would justify more of the effort being
shifted to the education of fugitive dust sources as to the requirements
they must meet and the enforcement of the fugitive emission regulations.
NETWORK DESIGN
The monitoring network for the AQCR (Figure 1) is designed to define
the spatial distribution of TSP concentrations within the Denver metro-
politan area, where emissions are concentrated, and to monitor the out-
lying smaller population centers which are subject principally to fugitive
dust emissions at single in-town locations. Because of the widespread
nature of the AQCR and the fact that the TSP problem is centered in the
Denver metropolitan area, no analysis of the sites of these outlying
monitors was carried out.
Within the Denver metropolitan area (Figure 2) , the area of greatest
concern lies along the Platte River Valley. This is a result of the
concentration of industrial, commercial and residential sources along the
valley and the prevalence of a dally wind regime during light-windspeed,
high-pollution days under which the local air mass drifts down the valley
during the night and returns during the day. Details are given elsewhere
48
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in the section of this report covering meteorology. The requirement for
monitoring concentrations along the valley appears to be satisfactorily
met by six monitors distributed roughly along a NNE to SSW line and
extending for a distance of 13 kilometers from Littleton in the south
through the central business district (CBD) to Adams City in the north.
Of these six monitors, one is located in the CBD, one is located on the
outskirts of the CBD in a mixed commercial-industrial area, one is
centered within the principal industrial area of Denver at an open ex-
posure location, one is slightly removed from a major north-south com-
mercial street which passes through a residential area, and the re-
maining two are located at the southern and northern ends of the sampling
line. The monitoring network also covers areas of recent and projected
growth from Arvada and Lakewood west of Denver, to Aurora in the east.
These areas, being at elevations of the order of 100 to 200 feet above
the valley floor and somewhat removed from the areas of maximum emissions,
experience lower concentrations than those within the valley proper.
The 15 monitoring sites used in this study which were operating within
the Denver metropolitan area in 1974 have 'been grouped in Table 12,
according to the predominant neighborhood characteristic of each. In
addition, Table 12 provides the annual 1974 geometric means, monitor
heights and, for sites visited by GCA personnel in the course of this
study, special siting comments.
With few exceptions, the hi-vols are on the roofs of one- and two-story
buildings and well exposed to the general air flow. The monitor on the
roof of the State Health Department Building is at a height of 60 feet
and somewhat sheltered from air flow from the southeast. Very limited
information on the vertical gradient of TSP concentration in urban areas
suggests that concentrations at the more standard Denver monitoring
height of 15 to 25 feet in this area would exceed those measured at 60
feet by 10 to 15 percent. The principal CBD monitoring site is at a
height of 50 feet on the roof of the School Administration Building. The
hi-vol at this site is well exposed, not being subjected to any street-
canyon effect as a result of neighboring high-rise building. It should
49
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Table 12. ANALYSIS OF 1974 TSP MONITORING SITES IN DENVER
elghborhood
nUeBtlal/coBBerclal
Center City
Coaaerclal
Industrial
touts
State
Identification
mater
2
1
9
13
BB
96
110
3
5
IS
59
1
4
8
11
Location
State Health Dept., Denver
Aurora
Englevood
Lakevood
Uestalnster
CAR IB, Denver
Centenlal Wells, Uttleton
Gates Bldg, Denver
School Adnin. Bldg., Denver
Arvada
Edgewater
Hull Photo, Denver
Sewer Plant, Denver
Adams City
Cherry Creek Da, Arapafaoe County
1974 annual
geoaetrle aeaa
(lig/-3)
74
89
107
80
76
93
86
Ave (86)
119
107
Ave (113)
107
91
Ave (99)
73
131
116
Ave (107)
63
Height
of
ml tor
(ft)
60
20
20
15
IS
15
t
25
SO
15
35
25
10
15
4
Siting cements
Highest eonltor site. Heavy traffic on Colorado Blvd.
one and a half blocks to vest. Predominantly resid-
ential except for light coanerclal along boulevard.
100 feet west by heavily traveled So. Broadway. Large-
ly residential except for light coaaerlcal along
Broadway. Soae unpaved alleys and partially bare lota,
Nixed Industrial/commercial area. Approximately
200 feet east of heavily traveled So. Broadway and
1000 feet southwest of the valley highway.
Second highest nonltor site. Not far froa urban
renewal. During the past few yeara blocks to west
and north of site have been demolished and replaced
with new buildings and paved parking lots.
Centrally located In principal industrial area of
Denver, north of CBD and on west bank of Platte
River. Stockyards and other sources of fugitive dust
nearby .
Open area, 90 feet from street, adjacent to paved
parking lot. General area seal-developed with
vacant lots and unpaved roads.
Ul
o
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be recognized, however, that concentrations measured at this site are
not representative of street-level concentrations within the CBD. For
example, the average concentration at the School Administration Building
for the 3 years from 1970 to 1972 was 120 ug/m3, while that measured at a
0
height of 9 feet at the CAMP station at 2105 Broadway was 170 yg/m .
A general conclusion is that the TSP monitoring network is well designed
and properly run. Because of the important part apparently played by
fugitive emissions in the Denver area and the need for a substantial
reduction in total emissions in order to meet the primary standards,
however, an increased monitoring program designed to provide better estim-
ates of incoming and city-generated particulates and of the relative
contributions of major sources of fugitive dust within the city - such as
street sanding and salting - would be helpful. Specific changes in the
monitoring network would include the establishment of a more uniform
height for all monitors and the location of several monitors arranged in
outlying areas to the west and southwest of Denver to provide a better
understanding of the background concentration entering the Denver area;
i.e., away from the outlying centers of population. Reductions in the
monitoring heights of the several higher monitors to a more uniform height
of around 15 feet should only be done after running current samples for
a reasonable period of time (at least 1 year) so that previous data can
be adjusted for final analyses. The concurrent operation of monitors at
different levels would also provide data on the contribution of local
fugitive dust sources.
51
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METEOROLOGY AND CLIMATOLOGY
The general meteorology and climatology in the Denver AQCR is strongly
influenced by the topography of the area and, in turn, has a significant
effect on the ambient levels of TSF. Because of Denver's location on
the eastern slope of the Rocky Mountains in the belt of prevailing
westerlies, the climate is generally mild and dry. The greatest amount
of precipitation occurs in spring when moist air currents from the Gulf
of Mexico meet weak polar outbreaks from the north. Wide local variations
in wind regimes along the foothills are introduced by mountain and valley
winds. Air drainage is generally good in the canyons, but as these can-
yons emerge onto the plains the slope is much less, and the air circula-
tion may become very sluggish along the wider river and creek valleys,
resulting in a drastically increased pollution potential. Other climatic
*
effects of the mountains on this area are reduced temperature variations
and increased precipitation as compared to those of the plains proper.
Due to the limits of time and data availability, the analysis of the
impact of meteorology on the pollution levels in the AQCR was limited to
the Denver County area and the data recorded at Stapleton International
Airport. The following discussion centers upon the two major meteorolog-
ical factors known to have a significant impact on Denver air quality
levels ventilation and precipitation. Supporting data on meteorological
parameters considered below is presented graphically In the appendix.
Ventilation
With a given set of emission sources, the degree of air pollution ex-
perienced within an urban area, including its spatial distribution and
the frequency and duration of its occurrence, depends largely upon
existing meteorological conditibns. The principal controlling meteor-
ological parameters are the wind speed and direction and the vertical
stability of the atmosphere within the first few hundred feet above the
52
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ground. To a large extent the wind speed governs the rate of dilution
experienced by the pollutants upon emission, and the stability controls
the rate at which pollutants can be mixed vertically and the thickness
of the atmospheric layer through which this mixing occurs. It follows
that the pollution potential for a region is greatest during periods
of light winds and strong surface temperature inversions.
The maximum vertical depth of the atmosphere available in any day for
the mixing of polluted air usually occurs in the afternoon following the
period of maximum surface heating and is known as the maximum mixing
height. The minimum mixing height is associated with minimum surface
temperatures and usually occurs at or around sunrise. For any given
wind speed, the greater the mixing height, the greater the volume of
air available to dilute the pollutants and therefore to lower their con-
centrations. During a typical 24-hour cycle, the depth of the mixing
layer in Denver varies by nearly one order of magnitude as a result of
radiational cooling of the earth's surface at night and solar heating
of the earth's surface during the day. The generally clear skies and
low humidity of the area contributes markedly to the amplitude of this
diurnal cycle. Afternoon mixing heights are least in the fall and win-
ter and greatest in the spring and summer, ranging from a low of about
1300 meters in December to a high of about 3600 meters in May. The mean
morning mixing heights range from about 175 to 450 meters, with the
greatest heights again occurring in the spring and early summer.
Since a greater mixing height generally Implies a lower concentration,
Figure 17 presents the ratio of the average mixing height to the
monthly mixing height for both morning and afternoon and also the ratio
of the county-wide 1974 monthly geometric means to the 1974 annual geo-
metric mean in Denver. Though the data from which the mixing height
graphs were constructed is not specific to 1974 but rather an 8-year
mean, the seasonal pattern in the data is a recurring phenomenon and is
felt to be representative of the general pattern in 1974. While both
53
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2.0
1.8
1.6
1.4
1.2
I"
" 0.8
0.6
0.4
0.2
0
M
M
J J
MONTH
N
Figure 17. Average/monthly mean morning and afternoon mixing heights and
county-wide monthly/annual geometric means of TSP in Denver.
54
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mixing heights demonstrate the overall ventilations in the region, the
morning mixing height is of more interest as it is the lowest of the
cities studied. At the same time, the afternoon mixing height is the
highest of the fourteen cities and indicates relatively good mixing even
in the winter months.
The seasonal pattern in morning mixing heights indicates that concentra-
tions would normally be higher in the winter and fall than during the
spring and summer. The pattern of higher winter than summer is paralleled
in the TSP ratio curve but the spring and fall differences are reversed
for TSP. This could be due to numerous factors including other meteoro-
logical factors and emission rates (e.g., more agricultural tilling and
ground breaking for construction in the spring).
A similar fall and winter versus spring and summer pattern is evident
from the frequency of low level inversions observed during these seasons.
On most nights of the year in the Denver area, temperature inversions
form at or near the surface; these inversions range from a few degrees
to 30 F or more in extreme cases. While the frequency of low-level in-
versions are comparable in the early morning hours throughout the year
(see Table 13), the daytime heating rapidly breaks up the inversion
Table 13. PERCENTAGE OF FREQUENCY OF LOW-LEVEL INVERSION1
(STAPLETON INTERNATIONAL AIRPORT)
Season
Fall
Winter
Spring
Summer
5 p.m.
22
54
5
8
8 p.m.
78
82
58
54
5 a.m.
80
83
65
84
8 a.m.
49
75
22
15
Hosier, Charles R., 1961: Low-level inversion
frequency in the Contiguous United States.
Monthly Weather Review, vol. 89, Sept., 1961,
319-339
55
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in the spring and summer months, as shown by the 8 a.m. values. The
impact of the ceiling effect of inversions in Denver is compounded by
the topography which further limits the ventilation. Figure 16
presents a cross-section profile of pollution layer depths over Denver
on days when temperature inversions are not eliminated.
The major topographical influence on the wind regime in the area is
related to this trapping of air masses in the valley of the South Platte
River. As was shown in Figure 18, the South Platte River passes through
the City of Denver, flowing from southwest to northeast. Under light
nighttime wind conditions surface air, made relatively more dense by
radiatlonal cooling, drains down the river valley toward the northeast
and lower elevations. This cold air drainage apparently stops just
beyond the suburbs and the shallow air mass, which has accumulated pol-
lutants from city sources, is frequently brought back by a sudden wind
reversal around noon. Although this change in wind direction probably
reflects, in part, upslope winds produced by surface heating during the
morning, the driving mechanism for the reversal is not fully understood.
Under a light wind regime, crossing and re-crossing of the pollutant
sources by the same air mass may continue for several days, thus leading
to an excessive local accumulation of pollutants. The sketches in Fig-
o
ure 19, taken from Rlehl and Crow, show composite wind fields prior
to, during, and following such a wind reversal, and the southerly drift
of the returning edge of the polluted air mass on one such day.
An estimate of the impact that the topography had on the wind regime
during the monitoring in 1974 may be determined from the graph of the
frequency of wind direction during sampling periods in Figure 20.
This graph indicates that the greatest frequency of wind direction while
the monitors were operating was from the southerly direction with 35 per-
cent of the wind from a sixty degree sector centered just west of south.
Almost another 20 percent of the observations occurred in the 60 degree
sector centered around north-northwest.
56
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000 -....
I TOCO -
I tOOO -
-MOO
5000
Figure 18. Typical WNW-ESE profile of pollution layer depths over
metropolitan Denver between 0800 and 1500 on days when
temperature inversions are not eliminated
57
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/ // te
15 December 1961
Figure 19. Average wind during pollution episodes from 10 a.m.
to 2 p.m. (a, b, c). Length of arrow indicates one-
hour air movement. Curves in "d" indicate forward
edge of polluted mass at indicated times during
southward advance of polluted mass. (From Riehl
and Crow, 1962)
58
-------
o
o
o_
o
u.
8
60.00 120.00 180.00 240.00 300.00 360.00
WIND DIRECTION (DEGREES)
Figure 20. Percent of observations versus wind direction
in Denver
59
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Another meteorological parameter related to the ventilation in the area,
and for which 1974 data is available, is the windspeed. This, data (see
Appendix) indicates only a minor range of average monthly windspeeds
(7.1 mph in September to 10.1 mph in April), with the winter and summer
windspeeds being fairly comparable. The pattern in windspeed of higher
values in the spring and lower in the fall would tend to support the
mixing height argument that TSP concentrations should be lower in the
spring than in the summer.
Precipitation
Aside from ventilation, precipitation is normally considered to be the
meteorological parameter which has the maximum impact on air quality
levels. It helps to clean the air of particulates through washout and
rainout and can suppress the rise of pollution levels by wetting down
particulates that would be resuspended if dry or even washing particulates
off the streets into sewer systems if the rain is heavy enough. The ex-
pected relationship is one of inverse correlation with the pollutant
concentration.
Denver is an arid region with a normal annual precipitation level of
15.5 inches spread over 88 days. In 1974 the annual precipitation was
slightly over 14 inches and precipitation greater than or equal to 0.01
inch occured on 83 days. From the small amount of data available for
analysis, precipitation does not appear to have the same degree of im-
pact that has been observed elsewhere. Figure 21 provides an inverse
graph of the precipitation over the past 18 years by dividing the normal
(1947-70) precipitation level by that which occured in each of the years.
Overlayed on this figure are the annual geometric means for particulates
measured at the NASN station at 2105 Broadway in Denver. The graphs in
this figure indicate a relatively weak correlation between precipitation
and the TSP levels sampled at this station and therefore other cir-
cumstances and conditions at this site must be overriding any impact
that precipitation is having on the annual levels.
60
-------
_l
<
2.0
1.8
z
2 1-6
^ j 1-4
i z 1.2
1 S
O 2
<
140 =*.
k
1202
t-
80 g
60 I
a.
40 {2
20
1974
Figure 21. Normal/yearly precipitation and TSP concentration
at Denver NASN station, 1957 to 1974
-------
To discount the impact of conditions at an individual site, mean county-
wide concentrations were compared with the precipitation levels from 1969
through 1974. For the determination of the relative impact of changes in
precipitation on the changes in air quality, both the inverse ratio of
precipitation and the ratio of the county-wide annual geometric mean to the
county-wide 6-year geometric mean were plotted in Figure 22. This
graph also indicates minor correlation between annual precipitation levels
and TSF concentration in Denver County.
A better way of determining the relationship between precipitation and
air quality levels is to consider a citywide average of air quality,
thereby discounting major influences that certain activities may have on
an individual cxte, and precipitation during 1 year. Such an analysis
was performed utilizing 1974 data and monthly fluctuations over the year.
A major advantage of this 1-year analysis is that wider fluctuations in
the meteorology are expected on the smaller time scale and these wider
fluctuations should be reflected in the air quality levels if there is
a correlation. While one problem of changes in emissions over long time
scales is eliminated, the additional problem of seasonal fluctuations in
the emissions levels is present.
Again in the interest of normalizing the rainfall levels and wanting to
show comparable changes in precipitation and air quality, Figure 23
provides a graph of the average monthly geometric mean divided by the
annual geometric mean for all monitors in Denver County along with the
normalized inverse of monthly precipitation (average monthly/monthly).
From this graph it is evident that there is some correlation between
precipitation and concentration but that it is not a very strong one and
that while above normal periods of rain (April, June, July, October)
tend to decrease the ambient concentration of particulates, below normal
amounts (May, August, December) have little if any impact on the monthly
TSP levels.
62
-------
<
-------
INVERSE
PRECIPITATION
M J J
MONTH
N
Figure 23. Average monthly/monthly precipitation and countywide
monthly geometric mean/annual geometric mean for TSP
in Denver, 1974
-------
One possible explanation for the lack of a strong relationship Is the
relatively small amount of precipitation and the infrequency of occurrence.
It Is not unreasonable to assume that the more frequent the precipitation,
and the greater the amount, the more impact it would have on the annual
and monthly levels; i.e., if only a few samples are reduced during the
year or month, the geometric mean would not be noticeably changed.
Analysis of the TSP concentrations on the day of or the day after pre-
cipitation, both rainfall and snowfall, is presented in the discussion
of sanding activities.
URBAN ACTIVITY
Several areas of urban activity were investigated in the course of this
study to determine how these activities impacted on the measured ambient
air quality. Principal among these were sanding for snow control, street
sweeping and construction. A cursory analysis of this latter area in-
dicated that it was not a citywide phenomenon of interest having any cor-
relation with citywide TSP levels and more detailed analysis was felt to
be beyond the current scope of effort. Therefore, the following dis-
cussion centers on the analyses conducted on sanding and sweeping activities.
Sanding and Salting
The City and County of Denver, Department of Public Works, spread over
13,000 cubic yards of sand and salt on the roads of Denver in 1974 and
this sanding activity has been implicated in several studies3*10 as con-
tributing a large amount of partlculates to the air through the grinding
and resuspension by vehicles on the paved surfaces. The possibility that
sanding has a major impact on the countywide levels of TSP was considered
in several analyses.
Total Tonnage Calculations - The figures given in the PEDCo study of
fugitive dust in Colorado3 indicate that 5,816 tons per year of particulates
65
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were added to the air in Denver County in 1972. This tonnage figure was
calculated in part by assuming an average of about twelve heavy snowfalls
during the year, a reasonable assumption given 1974 data, and also that
the sand remained on the road after the snow melted until sweeping opera-
tions removed the sand. This latter assumption yielded approximately
18 days of dusty paved roads per year (36 hours before street sweeping
operations). The actual calculation of the tonnage emissions was based
on a study of emissions from dusty paved roads in the Duwamish Valley of
Seattle, Washington, which gave an emission rate of 0.17 pounds per
vehicle mile (VM). The vehicle miles traveled in Denver were assumed to
be 80 percent of normal after the snowfall had melted.
As the calculation of emissions from sanding was not directly related to
the sanding activity itself, an analysis of the assumptions used in the
calculations was conducted. From this analysis the following points
were raised.
While there were approximately 12 "major" snowfalls in
1974, there were about 18 major periods of sanding activity
due to the need to respond to small snowfalls also.
Sanding activity actually occurred on 50 different days in
1974.
Streets are swept on the average of five times per year so
it is not likely that sand would be removed from the street
within 36 hours.
While traffic may be less than normal during the snowfall
and while the snow is on the streets, once the snow has
melted the average daily traffic should return to normal,
especially considering the length of time that the sand
must remain on the road.
The emission rates were based on a study* which calculated
the rates from isokinetically sampling the air behind a
moving car.
The first four of the items listed above tend to indicate that the tonnage
calculation by PEDCo may have grossly underestimated the total tonnage that
should be calculated using that methodology. At the same time, the
66
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Duwamish Valley study tends to give an emission rate that is too high.
While the emissions directly behind an automobile on a dusty road may be
0.17 Ib/VM, the resulting emissions that actually remain airborne and
transported more than a few feet of the ground and away from the road can
be expected to be much less. In addition, the Duwamish Valley study was
concerned with the carryout of mud and dirt from unpaved roads and parking
lots. The very nature of this carryout material would imply that it is
selectively more adhesive to the tires and more readily picked up in
transit; i.e., mud and sand would not have the same emission rate.
The fact that the tonnage calculations performed by PEDCo could be larger
or smaller than the actual emissions from sanding provides no resolution
as to the final accuracy of this figure. One approach that does provide
at least a ceiling on the emissions possible from sanding operations is
the determination of the total tonnage applied to the roads in Denver.
Data provided by the Department of Public Works for the City and County of
Denver gave a total volume of salt and sand mixture spread in Denver roads
in 1974 as 13,638 cubic yards. Since the salt to sand ratio used in
Denver is 1 to 5 and 1 cubic yard of the samd (actually three-eights
inch aggregate) weighs 1.4 tons, the total tonnage of sand added to the
roads in 1974 was 15,911 tons. A comparison of this tonnage with the
PEDCo emission rate of 5,816 tons would imply that over 35 percent of the
sand added to the road ends up as air contaminant. Under the assumptions
that: (1) some of this three-eights inch^aggregate is bounced into the
gutters by passing cars, as would be some of the sand ground from passing
cars; (2) some of the sand and gravel would be collected by street plowing
and snow removal operations and thereby disposed of elsewhere; (3) the sand
would be evenly dispersed over the road with more tendency to accumulate on
sections of the road other than where the tires are most frequently
traveling; and, (4) some street sweeping operations do occur, this per-
centage emission rate would appear to be extremely high.
67
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This analysis brings into question the appropriateness of the emission
estimate given in the PEDCo study for strategy planning purposes. While
5,800 tons or much more may actually be temporarily reentrained due to the
traffic on sanded paved roads, the duration of this reentrainment and the
distance of transport of these emissions must be considered in the analysis
for strategy planning.
Seasonal Fluctuations - One method of determining the "equivalent" emis-
sion rate for sand on paved roads would be through modeling the emissions
and correlating the modeled TSP levels with actual air quality measurements.
As this approach was beyond the scope of this effort, an. alternative
analysis was conducted by comparing the estimated monthly emissions from
sanding operations with the countywide monthly geometric means of TSP con-
centration. Tne mechanics and direct results of this analysis were
presented above in the section on emissions. In that discussion it was
shown that a correlation did exist between the monthly emissions of fugitive
dust and the monthly TSP levels. However, it was also suggested that the
correlation might be much closer if an emission rate of one-half that cal-
culated by PEDCo was assumed.
Further analysis that was conducted under the discussion of meteorology
indicated that the seasonal patterns in TSP levels may be just as well
correlated with seasonal changes in mixing heights and the frequency of
low level Inversions. As these latter parameters are much less susceptible
to errors in their determination than the calculation of seasonal emis-
sions, it must be assumed that, regardless of whether street sanding is
practiced, the TSP levels in the winter would be higher than those in
the summer.
Therefore, the fact that the ratio of monthly emissions to the average
monthly emissions is comparable to the ratio of above background monthly
levels of TSP to the annual emissions does not immediately mean that a
correct apportionment of emissions has been made. Rather, given the
seasonal meteorological influence, lower emission ratio than TSP
68
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concentration ratio would be the expected norm. In the case of the
Denver emissions, one method of obtaining a lower ratio in the winter
months would be to assume a much lower value of emissions from sanding
activity.
Daily Fluctuations - The City and County of Denver, Department of Public
Works provided information regarding the quantity of sand and salt mix-
ture spread in Denver for each day in 1974. This data, along with snow-
fall records from the U.S. Department of Commerce and TSP levels for
six monitoring sites from the Colorado Department of Health, were com-
pared for those months when sand and salt mixture was spread (January
through April, November and December).
Several observations were made from this analyses:
Several days after sand is spread, TSP levels increase
to an apparent peak and then decline to pre-storm levels.
The lag time between sanding activity and peaking TSP
levels varies between 1 and 11 days with 2 to 4 days
being the most common range.
It is not known precisely when TSP levels peaked and
what the magnitude of that peak was because readings
are recorded every 4th day. Hence, the actual peak
and the apparent peak may be offset by as much as 3 days.
Accordingly, the actual peak TSP level will exceed the
apparent peak TSP level in those cases where the actual
and apparent peaks do no coincide.
For specific storms the lag time between sanding opera-
tions and the apparent peak TSP levels appears to
decrease as the quantity of sand and salt mixture spread
increases. There is no apparent relationship between
the lag time between sanding activity and peak TSP
levels and the magnitude of the peak level.
The magnitude of the increase in TSP levels varies from
a high of 309 pg/nr above the monthly average at the
lowest monitor (Sewer Plant) on Friday, January 25th
after 1,570 cu. yd. of sand was spread between January 21
and 23, to a low of 70 pg/m below the monthly average at
the same monitor on Thursday, April llth after 335 cu. yd.
of sand was spread on April 3rd.
69
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For the 13 storms considered, an average of 945 cu. yd.
of sand was spread and an average increase in TSF levels
of 54 ug/m-* was observed at the apparent peak. It is
difficult to quantify the extent to which sanding
operations were responsible for this increase. At least
part of the increase could be due to the normal variation
in ISP levels.
There is no apparent quantifiable relationship between
increases in TSP levels and the amount of sand spread.
It appears that meteorological factors (temperature,
wind and precipitation) may also have a strong influence
on the magnitude of the increase.
TSP levels during periods of snowfall are usually lower
than the monthly average. The magnitude of the difference
varies fror: a high of 217 yg/m^ below the monthly average
at the S«-wer Plant on Wednesday, January 9th to a low of
96 ugAsH above the monthly average at Gates on the same day.
For the 13 storms considered, the average difference
in TSP levels during periods of snowfall was 49 ug/m
below the monthly average. Thi£ is not to say that
snowfall is responsible for the entire decrease. At
least part of the decrease could be due to the normal
variation in TSP levels, the cumulative effects of
snowcover on the ground and inswept sand.
This preliminary review did not lead to any direct relationship between
snowfall and the amount of sand spread. Other meteorological factors
such as temperature, wind speed, and snowcover are also important. In
addition, it could be considered equally likely that the snowfall is
depressing normally high values as that the sanding operations are in-
creasingly normally low levels.
In an attempt to separate out the effect of the storm systems and the
precipitation itself, a comparison of the daily TSP levels before and
after precipitation was made between the winter storms (snowfall) and
summer storms (rainfall). This analysis was based on the differences
between the ambient particulate concentration on the sampling days around
the time of the precipitation with the geometric mean for the sampler for
the month in which the precipitation occurred. In the case of rainfall,
70
-------
this was a straight comparison of the sample immediately before the rain-
fall with the monthly mean and of the sample closest to after the rain-
fall had ended. For snowfall however, the problem of snowcover lasting
for several days precluded the use of the sampling date immediately
following the snowfall. Instead, the peak value after the snowfall was
used. Table 14 presents the total difference found by comparing the
daily with the monthly, the number of samples that were taken, and the
average difference in samples for each day.
The data in this table indicates that before periods of snowfall, the
air quality would appear to get increasingly better as the storm approaches,
but for rainfall the only consistent improvement is on the actual day
of rain and the day after. The difference may lie in the fact that snow-
fall is normally associated with a storm system while rainfall may occur
with less associated activity. While the rainfall appears to suppress
particulate levels for 1 day, TSF levels rise quickly after a snowfall
with perhaps a peak on the second day after snowfall. This phenomenon
may be attributable to the sanding activity but may also be a result of
the impact of the passing storm system.
Street Sweeping
If sanding were found to be having an impact on the monitored levels of
TSP due to resuspension caused by vehicle traffic, then it might be ex-
pected that the removal of excess dirt from the paved roads would bring
about a reduction in the ambient levels. In the course of this study,
data on street sweeping activities in Denver was gathered and compared
with the daily TSP readings at the monitors in the vicinity of the sweep-
ing. For maximum impact on the monitors, sweeping activity was oniy
considered in the analysis if it occurred within an approximately one-half
kilometer (about 6 blocks) radius of the monitor and within 2 days prior
to sampling.
71
-------
Table 14. COMPARISON OF TSF CONCENTRATIONS BEFORE AND AFTER SNOWFALL AND RAINFALL STORMS
ro
toys
'Before
3
2
1
0
After
1
2
3
4
5
6
7
8
9
10
11
Total difference:
dally TSP-monthly TSP
-------
Since street sweeping does not occur in Denver on any definite schedule
and the blocks are swept an average of only five times per year, very
few pairs of ambient monitoring and street sweeping activity were found.
To further hinder the analysis, only one of the pairs was at a sampler
10 feet off the ground and one pair was at a sampler 25 feet off the
ground. The other paired activities were all near monitors at heights
of 50 to 60 feet.
The analyses conducted on these paired observations included a comparison
of the ambient concentration measured after street sweeping with the
corresponding monthly and annual geometric means for that monitor and
also a review of the pattern of increases and decreases in TSF levels
measured at other monitors in the city on that day. These analyses pro-
vided no correlation at all between street sweeping activity and ambient
levels. The TSP concentrations after sweeping were both higher and lower
than the monthly and annual geometric means and no deviation from the
4-day pattern of TSP at all monitors in the city was observed.
Despite the finding of no correlation, the conclusion that no correla-
tion exists can not be made due to the inadequate data base. More paired
observations and samples closer to the ground would be appropriate for
further study.
73
-------
SECTION III
SUMMARY AND CONCLUSIONS
The analyses presented in Section II of this report indicate that many
factors have contributed to the lack of attainment of the NAAQS for total
suspended particulate in the Denver AQCR. These factors have ranged from
the problems in developing an appropriate emission inventory to the in-
fluence of topography and climatology. This section attempts to review
the circumstances that brought about the current conditions and make
recommendations where possible on measures necessary for the attainment
of the particulate standards.
PRIOR ATTAINMENT STRATEGY APPROACH
The Air Quality Implementation Plan for the State of Colorado based its
control strategy development for suspended particulates on the highest
2
reported annual geometric mean of 122 ug/m , which occurred in Denver.
This value determined required emission reductions of 51 percent and 67
percent to meet the primary and secondary standards, respectively. The
reduction of 51 percent was to be achieved in part by the application of
Regulation No. 1 with the balance being met by the application of Federal
particulate emission control regulations on automobiles and aircraft.
(Federal regulations directed at controlling particulate emissions from
automobiles were never promulgated.) The reduction of 67 percent to at-
tain the secondary standard was assumed to require emission reductions
exceeding those which can be achieved through the application of reasonably
available control technology (RACT) so an 18-month extension was requested,
and granted by EPA, in order to formulate and submit that portion of the
SIP.
74
-------
Regulation No. 1, as presented in the SIP, was projected to decrease
stationary source particulate emissions in the Metropolitan Denver AQCR
from 18,096 tons/year in 1970 to 8,425 tons/year in 1975, or a reduction
of 46 percent. The control measures imposed to receive this reduction
included a general requirement that emissions could not obscure vision
to a degree greater than 20 percent opacity, a ban on open burning without
a permit, and process rate based regulations for major fuel-burning equip-
ment, refuse-burning equipment, and manufacturing processes. Control of
fugitive dust, at the time of the SIP, was based on the 20 percent opacity
regulation and the need for five or more complaints.
In searching for particulate emission sources where additional emission
reductions could be demonstrated as part of the plan to achieve the
secondary standard, the Colorado Air Pollution Control Commission identi-
fied fugitive dust from unpaved roads and other sources as contributors
to particulate pollution which were amenable to control. The agency next
drafted regulations designed to provide the best control feasible for the
fugitive dust sources that they had identified. However, due to lack of
available data on (1) emission rates from these sources and (2) the ef-
fectiveness of the proposed regulations in reducing particulate emissions,
the Commission was unable to quantitatively demonstrate that the fugitive
dust controls would result in the necessary reduction in emissions.
To compound this problem of presentation, measured particulate levels at
some sampling sites were increasing with time, rather than decreasing ac-
cording to the projections of the initial implementation plan. This
divergence of actual measurements from projections indicated that the
emission inventory on which the control strategy was based did not ac-
count for all emission sources affecting the samplers.
A study was thus undertaken to quantify the reduction in fugitive dust
emissions that can be expected from enforcement of the proposed regula-
tions and to estimate the resulting air quality in three Colorado Air
75
-------
Quality Control Regions with these regulations in addition to existing
control regulations. The resulting emission inventory showed that, in
the Denver AQCR, unpaved roads were the largest source of particulate,
accounting for 35 percent of the particulate emissions inventoried. The
other eight fugitive dust categories - sanded paved roads (for snow con-
trol), land development, agriculture, building construction, highway con-
struction, quarrying/mining, aggregate storage, and cattle feedlots - also
contributed significant emissions on a regional basis, so that fugitive
dust was responsible for 70 percent of particulate emissions in the Metro-
Denver AQCR. In Denver County, 62 percent of the particulates were esti-
mated to be from fugitive dust and 73 percent of this was determined to
be the result of sanding activities for snow control. In response to this
emission inventory, the Colorado Air Pollution Control Commission has re-
cently promulgated a new regulation for the control of fugitive dust.
However, even with these additional provisions, it is unlikely that even
the primary standards will be achieved in the AQCR. The major problems
in achieving the standards are the large contribution of fugitive dust to
total particulate emissions" in the regions and the low control efficiencies
attainable for most fugitive dust sources. In fact the Federal secondary
particulate standard of 150 ug/m (24 hour) is exceeded in almost com-
pletely undeveloped areas. The high winds in these semlarld areas of
sparse vegetation are the cause of the violation of standards due to their
uplifting action on the dusty ground cover.
A major problem in formulating appropriate control strategies for the at-
tainment of particulate standards in the Denver AQCR has been the estab-
lishment of a complete and accurate emission inventory. Aside from the
original exclusion of fugitive dust in the SIP's emission inventory, there
have been several emission inventories generated and used for planning
purposes. These inventories have most often had wide discrepancies in the
total emissions as well as other emission levels attributed to different
76
-------
source categories. Inconsistent, and therefore inaccurate, data must be
one of the principal causes of the lack of success of the attainment
strategies.
In addition to the exclusion of fugitive dust and the continuing incon-
sistencies of emission Inventories, planning activities in the AQCR, es-
pecially under the SIP, have failed to take into account the significant
impact of the topography and ventilation characteristics of the region.
Common air quality models cannot accurately represent these outside param-
eters which are so important in Denver. The roll-back calculations uti-
lized in the SIP are even less appropriate.
RECOMMENDATIONS
Much of the problem with the attainment of the particulate standard in
the Denver AQCR lies in the exact definition of the situation with re-
spect to particulates. If the standards are to be attained, more inten-
sive study will have to be conducted than has been done in the past.
Specific areas which, in the course of this effort, have been identified
as needing further study prior to another attempt at planning are listed
below:
Conventional Emission Inventory - More updating of the
current emission inventory is needed than has recently
been done utilizing the CAPCD's air contaminant emission
notices, many of which are 5 years old. Due to the strong
seasonal influence of meteorology, this update should have
detailed information on the seasonal emission patterns.
At the same time, trends information should be compiled
to serve as a guide In strategy planning.
Fugitive Dust Inventory - Further study of the emission
rates from possible fugitive dust sources is needed if
fugitive emissions are to be considered in strategy plan-
ning. These emission rates must be better defined than
they are currently and should reflect an effective emis-
sion rate rather than an actual emission rate to include
only those particulates that remain airborne sufficiently
long to be considered air contaminants.
77
-------
Network Design - Pending future requirements for a fixed
monitoring height, CAPCD should reconsider its location
of monitors at varying heights within the city. The in-
consistency of heights hinders the determination of a
uniform control strategy for fugitive dust as the higher
samplers will not show the improvement that may be found
at a lower monitor.
Meteorology and Topography - Further attention must be
given to these factors in the future development of con-
trol strategies. As strong seasonal patterns are likely
to result solely due to changes in the meteorology, an-
nual and average 24-hour modeling cannot be expected to
provide control measures that have comparable Impacts
throughout the year.
78
-------
REFERENCES
1. GCA/Technology Division. Development of an Example 10-Year Air
Quality Maintenance Plan for the Denver AQMSA. Prepared for U.S.
Environmental Protection Agency, Research Triangle Park, N.C.
EPA-45073-74-053. September 1974.
2. Cowherd, C. C. et al. Emissions Inventory of Agricultural Tilling,
Unpaved Roads and Airstrips, and Construction Sites. Prepared for
the U.S. Environmental Protection Agency, Office of Air and Waste
Management, Office of Air Quality Planning and Standards. November
1974.
3. PEDCo-Environmental Specialists, Inc. Investigation of Fugitive
Dust - Sources Emissions, and Control - for Attainment of Secondary
Ambient Air Quality Standards, Colorado. Prepared for the U.S.
Environmental Protection Agency, Office of Air Quality Planning
and Standards.
4. Martin, W. and A. C. Stern. The Worlds Air Quality Management
Standards, Volume II: The Air Quality Management Standards of the
United States. Office of Research and Development, U.S. Environ-
mental Protection Agency. Washington, D.C. EPA-650/9-75-001b,
October 1974.
5. The Research Corporation of New England. Impact of New Source
Performance Standards on 1985 National Emissions from Stationary
Sources. Final Draft Report. Prepared for the U.S. Environmental
Protection Agency. February 1975.
6. Colorado Department of Health, Air Pollution Control Division.
Air Quality Implementation Plan for the State of Colorado. Sub-
mitted January 1972.
7. Area Source Emission Inventory for Colorado. Prepared for the U.S.
Environmental Protection Agency by TRW. 1973.
8. Updated Point Source Emission Inventory data was provided by PEDCo
during the course of this study.
9. Riehl, H. and L. W. Crow. 1962: A Study of Denver Air Pollution.
Dept. Atmos. Sci., Colorado State University, Tech. Rept. No. 33.
10. Reiter, Elmar R. et al. Further Studies of Denver Air Pollution.
Atmospheric Science Paper No. 105. December 1966.
11. Roberts, John W. The Measurement, Cost and Control of Air Pollu-
tion From Unpaved Roads and Parking Lots in Seattle's Duwamish
Valley. A thesis submitted in partial fulfillment of the require-
ments for the degree of Master of Science in Engineering, Univer-
sity of Washington, 1973.
79
-------
APPENDIX A
METEOROLOGICAL DATA
80
-------
60
90
30
20
10
RECORD
MEAN
1957
I960
1963
1966
YEAR
1969
1972 1974
Figure 24. Yearly rainfall in Denver
81
-------
V)
Ul
X
u
LJ
o
<
oc
(U
10
9
8
7
6
5
4
3
2
I
.0
AVERAGE
1974
M
M
JJ
MONTH
N
Figure 25. Monthly rainfall in Denver
82
-------
i
o
<
o
UJ
UJ
U
20
18
16
14
12
IO
8
6
4
2
0
AVERAGE
1974
M
M J J
MONTH
N
Figure 26. Monthly number of days of rain in Denver
83
-------
8000
6500
g 5SOO
RECORD
MEAN
W
o
u
o
u.
o
4900
35OO
2500
I50O
500
I
1957 I960
1963
1966
YEAR
1969
1972 1974
Figure 27. Yearly heating degree days in Denver
-------
A S 0
N
MONTH
Figure 28. Monthly heating degree days in Denver
85
-------
X
Q.
O
hJ
£
CO
O
u
O
<
a:
UJ
20
IB
16
14
12
10
8
6
4
2
0
AVERAGE
1974
M
M J J
MONTH
N
Figure 29. Monthly windspeed In Denver
86
-------
APPENDIX B
PARTICLE CHARACTERIZATION
For most of the study cities members of the GCA study team acquired
hi-vol filters from the 1974 filter banks of the cognizant local agen-
cies. In addition, several filter samples for 1974 and selected earlier
years were obtained from state and federal filter banks. Although some
filters underwent chemical and/or detailed physical analysis, the prin-
cipal purpose of obtaining filters was to utilize optical microscopy to
identify each of the constituents that comprised more than five percent
of the particulate mass. The selected filters, which were representa-
tive of several different site types and TSP levels within each study
area, were returned to a clean room at GCA/Technology Division and care-
fully inspected for artifacts and evidence of sampler or filter mal-
functions.
Each filter was then assigned a randomly generated five digit number
which served as the only identifier for the filter sample so that each
analyst had no information concerning the city, site, TSP loading or
probable local sources associated with the sample. Furthermore, the
use of two laboratories for the microscopy, coupled with the randomly
generated identifying numbers, permitted a fairly comprehensive quality
control program in the form of blind replicate analyses. Since both
laboratories utilized more than one analyst, these procedures resulted
in as many as four microscopists observing samples from the sam? filter
and, in some cases, the same analyst examining replicate samples from
the same filter as many as three times.
87
-------
The results of this quality control effort, which are presented in Vol-
umes I and II, warn against relying very heavily on the results of any
one filter analysis. However, the random match-up between analyst and
filter sample should minimize systematic bias in composited results.
Twenty filters from four sites were selected for analysis in Denver and
Table 15 summarizes the meteorological data for the selected sampling
days. To gain some insight into the contribution of secondary partic-
ulates, much of which is too small to be observed by the microscopists,
the annual average sulfate and nitrate concentrations for the NASN site
are shown in Table 16. The results of each of the samples submitted
for routine analysis are presented in Table 17. The results for the
filters at each site have been averaged to give a composite of the par-
ticulate composition as shown in Table 18. Six filters underwent re-
plicate analyses, and the results of this task are presented in
Table 19.
The composite particulate characterization for all filters from Denver
that underwent routine analysis, presented in Table 20, shows that
minerals predominate the particulate material. Of the 14 study cities,
only one showed higher average percent minerals than Denver. The high
mineral contribution apparently is a citywide phenomenon with the aver-
age of each of the four sites studied ranging from 79 percent to 87 per-
cent. The major mineral constituent is quartz, which by itself com-
prises over half of the mass of the observed particles.
The relative contribution of combustion products to the Denver aerosol
appears to be very low. It is, in fact, the lowest percent contribution
for the category in any of the 14 study cities. If the microscopy re-
sults are a reliable indicator of the makeup of all the particulate col-
lected on the hi-vol filters, then the weighted average concentration
o
of combustion products on the 20 Denver filters would be only 11 ug/m .
88
-------
Denver was also one of just two study cities that were found to have a
higher percent contribution of rubber than combustion products. The
average percent rubber content in Denver was not excessively high com-
pared to the other study cities (Denver was fifth highest), but it does
support the theory of fugitive emissions, especially after road sanding
operations, being an important consideration.
Three of the filters from Denver were also submitted for determination
of particle size as a function of particle type, as shown in Figures 30
through 32. Two of these filters were also subjected to chemical
analysis. The filter from the State Health Department on June 14, 1974,
3 3
had 4 ug/m benzene solubles and Just over 12 ug/m total carbon with
nearly all of it reported as organic carbon. The filter from the School
3
Administration Building on the same day had over 12 iig/m benzene solubles
and about 15 ug/m total carbon, again nearly all reported as organic
carbon. The State Health Department filter from June 14, 1974, was also
selected for detailed physical analysis, and the results are presented
in Table 21.
89
-------
Table 15. METEOROLOGICAL DATA ON SELECTED SAMPLING
DAYS (STAPLETON INTERNATIONAL AIRPORT,
DENVER)
Date
1/25/74
6/14/74
6/26/74
7/20/74
12/19/74
12/27/74
Precipitation.
in.
Day of
oba.
0
0
t
0
0
0
Preced-
ing day
0
0.02
0
0
t
t
Wind speed, aph
Average
6.0
7.1
10.2
5.5
15.2
11.2
Resultant
4.2
3.3
4.8
1.3
12.8
10.8
Wind direction, deg
3-hour observation
C, 220, 210, 200
190. 80, 250, 250
320, 230, 200, 120
120, 90. 160, 200
180, 220. C, 10
50, 260. 130, 180
180, 190, 240, 30
80, 20, 310, C
310, 360, 270, 270
360, 310, 290, 330
210. 190, 190, 210
220, 160, 200, 190
Resul-
tant
210
150
190
30
300
200
Note: C
t
Calm
Trace
Table 16. ANNUAL AVERAGE CONCENTRATIONS OF
SULFATE AND NITRATE IONS AT THE
DENVER, COLORADO, NASN SITE NO.
060580001 (ng/n>3)
Year
1972
1973
1974
Sulfate
Arithmetic
mean
6.65"
8.41"
4.92"
Geometric
mean
5.70«
7.92«
4.80*
Nitrate
Arithmetic
mean
3.55«
7.36*
4.27*
Geometric
mean
3.13«
6.1la
4.08*
Indicates insufficient data for statistically valid year.
90
-------
Table 17a. RESULTS OF FILTER ANALYSES FOR SELECTED SITES IN DENVER AND VICINITY
(STATE HEALTH DEPARTMENT - NO. 2)
Date
ISP (M/B3)
a-ponent.
Hlnerali
Quart!
Calclte
Taldipari
BUBtlte
Mica
Caabuitlon
Product!
Soot:
Oil
Coal
Pine loot
Glaity
fly ish
Incinerator
fly agh
BotMd wood
Burned piper
tegnetite
Carbon black
Biological
lUttrUl
Pollen
Spore*
Paper
Starch
Ml »c. plant
tiMUt
HUcellaneous
Irom or iteel
loMer
25 January 1974
Quaa-
ttty.
tenthi
(9)
8+
a-)
i-
(Ot)
(1-)
1-
204
Siie
range.
M»
12
Av(.
alxe.
i»
9
1
14 June 1)74
77
Quan-
tity.
tenthi
(7+)
4
1
1
1-
1-
(»)
(Of)
(2+)
24
Size
range.
V
)
5*
1
1
1-
(0*)
d->
(1)
1
Slie
range,
no
<1-9S
A»g.
Ill,
M"
15
20 July 1974
68
Quan-
tity.
tenthi
(9->
s
1-
1
2-
1-
(Of)
«*>
(1)
1
Sire
range,
m
<1-7S
9-21
*7g.
lie.
\*
9
12
19 December 1974
76
Quan-
tity.
tenth a
(7)
4+
I
1
1-
U->
1-
(0«.)
(3)
}
SUe
range,
V
<1-31
9-75
Avg.
Ice,
lU
15
21
27 December 1974
90
Quan-
tity,
tenthi
-------
Table 17b. RESULTS OP FILTER ANALYSES FOR SELECTED SITES IN DENVER AND VICINITY
(SEWER PLANT - NO. 4)
Bate
Tsr (u*/« >
Component*
MneraU
Quartz
telelte
Feldspiri
Bnaatlte
HIM
CnecMUtlon
t Product!
Boot:
Oil
Coal
Soot
Glassy
fly ash
Incinerator
fly ash
Burned wood
Burned paper
Magnetite
Biological
Material
Pollen
Spores
Paper
Starch
Kite, plant
tissue
Ittaeellaneoua
Iron or steel
Bobber
25 January 1974
Quan-
tity,
teatha
(9)
6
1+
1-
u->
1-
(0*)
d->
!
MS
SllB
range,
M»
<1-80
<1-18
5-45
A»B.
alee,
M»
12
9
21
14 Juoa 19/4
111
Quan-
tity.
tentha
(8)
4
2+
14-
(1)
1-
(1-)
1-
(1)
1
Slse
range,
MB
1-80
5-80
»*».
else.
M"
12
1
30
26 Joe 1974
241
Quan-
tity.
tenth*
(9)
7
1
1-
(1-)
1-
(»)
1-
(2)
2
Slae
range,
)!
-.1-140
10-175
A*8-
alia.
U"
20
19 Daeeaber 1974
U3
Quan-
tity,
tentha
(8)
4+
14
1-
1-
1-
(0*-)
(0*)
(2)
2
SUe
range,
v»
1-140
10-130
A»g.
ICO,
ua
U
30
27 Dece^er 1974
226
Quan-
tity,
tentha
(8*)
7
1-
1-
(1-)
1-
(0*)
(1)
1
Slae
range,
V*
-------
Table 17c. RESULTS OF FILTER ANALYSES FOR SELECTED SITES IN DENVER AND VICINITY
(SCHOOL ADMINISTRATION BUILDING - NO. 5)
Date
TSP (ug/n1)
Components
Minerals
Quartz
Calclte
Feldspars
Henatlte
Mica
Combustion
Products
Soot:
Oil
Coal
V.f.soot
Soot par-
ticles
Glassy
fly ash
Incinerator
fly ash
Burned wood
Burned paper
Magnetite
Biological
Material
Pollen
Spores
Paper
Starch
Misc. plant"
tissue
Miscellaneous
Iron or steel
Rubber
25 January 1974
Quan-
tity,
tenths
W
5
3+
i
89
Size
range,
un
-------
Table 17d. RESULTS OF FILTER ANALYSES
FOR SELECTED SITES IN DENVER
AND VICINITY (ENGLEWOOD -
NO. 9)
Date
TSP (MS/0-3)
Component*
P'.ne-ala
Quart*.
Caleiee
Peldapara
Hematite
Mica
Coobuition
ProJueta
Soot:
Oil
Coal
Fine aaot.
Claaay
fly aah
Incinerator
Cly aah
Burned wood
Burned paper
Magnetic*
Biological
Material
Pollen
Sporea
Paper
Starch
Mtac. plant
tissue
MlaaalLa Mmi||
Iron or at**l
Inbher
SS January 1»74
230
Quan-
tity.
tantha
(10-)
a
i
i-
(Of)
(Of)
(Of)
Sice
range.
UB
<1-60
Avg.
lie,
um
10
1* JIM 1»74
114
Qjan-
tlty.
ceotha
(8-)
6-
1
1-
(1)
1
(Of)
(1)
Sice
range
0-65
<1-13
10-40
Avg.
alee.
um
a
i
M
-------
Table 18. COMPOSITE SUMMARY OF FILTER ANALYSES FOR SELECTED SITES
IN DENVER AND VICINITY
Site
No. of filters
Components
Minerals
Quartz
Calcite
Feldspars
Hematite
Mica
Hornblende
Combustion
Products
Soot:
Oil
Coal
Fine soot
Soot par-
ticles
Glassy
fly ash
Incinerator
fly ash
Burned wood
Burned paper
Magnetite
Carbon black
Biological
Material
Pollen
Spores
Paper
Starch
Misc. plant
tissue
Miscellaneous
Iron or steel
Rubber
State Health
Dept. No. 2
6
Quantity,
percent
Average
(80)
56
6
9
6
3
( 5)
1
1
<1
3
( 1)
<1
<1
<1
<1
1
(14)
14
Range
68-89
40-84
1-11
0-12
2-16
tr-5
1-19
0-5
0-4
0-1
0-19
-------
Table 19. RESULTS OF REPLICATE ANALYSES OF DENVER FILTERS
\C
Site
Date
TSP (ug/n3)
Laboratory
Analysis
Components
Minerals
Quartz
C^lcitc
Feldspars
Herwtlte
Mica
Corrbuarion
Produces
Soot:
Oil
Coal
V.f.sooc
Glassy
fly ash
Incinerator
fly asl-
Burned wood
Burned caper
Magnetite
Biological
Material
Pollen
SpTBS
Paper
Starch
Misc. plant
tissue
Miscellaneous
Iron or steel
Rubber
School Administration Bldg. - Ho. 5
25 January 1974
436
A
1
(90
52
35
3
1
( 3)
2
1
( 1)
<1
1
( 5)
<1
4
B
1
(25)
(75)
|
15
1
|OD
)
(<1)
(<1)
14 June 1974
89
A
1
(80)
46
18
3
9
4
(10)
B
2
(
( 5)
<1
5
Scwr Plant
Ho. 4
19 Deeeaber 1974
143
A
1
(78)
45
IS
4
8
6
( 1)
^l
1
( 2)
^l
^l
2
(19)
<1
19
A
2
(89)
50
25
4
10
<1
( 7)
4
1
2
(
-------
Table 20. CITWIDE COMPOSITE SUMMARY OF
FILTER ANALYSES IN DENVER
No. of filters
Components
Minerals
Quartz
Calcite
Feldspars
Hematite
Mica
Other
Combustion
Products
Soot:
Oil
Coal
Misc. soot
Glassy
fly ash
Incinerator
fly ash
Burned wood
Burned paper
Magnetite
Carbon black
Other
Biological
Material
Pollen
Spores
Paper
Starch
Misc. plant
tissue
Leaf
trichomes
Miscellaneous
Iron or steel
Rubber
Other
20
Quantity,
percent
Average
(81)
55
11
7
5
3
<1
( 7)
1
4
1
1
( 1)
<1
<1
<1
<1
1
(ID
<1
11
Range
62-97
37-84
1-35
0-15
1-18
0-6
1-19
0-20
0-14
0-5
0-19
0-7
0-4
0-7
0-32
0-32
97
-------
I
VO
00
80
ro
60
so
40
so
20
< 10
III
-I
o
*-
oc
z
I I I
i i r
0 QUARTZ
A COMBUSTION PRODUCTS
DFELDSPAR
I
0.01 O.I a5 I 2 5 10 20 30 SO 70 80 90 98 M 99 99.9
NUMBER PERCENT LESS THAN OR EQUAL TO STATED SIZE
99.9«
Figure 30. Cumulative size distributions for three particle types,
State Health Building, Denver, January 25, 197A
-------
I
to
TO
0
50
40
SO
2O
kl
VD
OC
<
10
9
8
7
6
5
4
I 1 I T
O QUARTZ
A COMBINATION PRODUCTS
D CLAY
0.01 O.I O.5 I 2 S IO 2O 50 SO 70 80 9O 95 98 99 99.9 9999
NUMBER PERCENT LESS THAN OR EQUAL TO STATED SIZE
Figure 31. Cumulative size distributions for three particle types,
State Health Building, Denver, June 14, 1974
-------
E
4.
0
70
60
90
40
SO
20
o
o
< 10
s:
h, 7
d 6
P »
S 4
i i
O QUARTZ
X OIL SOOT
D INCINERATOR FLY ASH
0.01 O.I as i 2 5 10 20 90 90 70 80 90 99 98 99 993
NUMBER PERCENT LESS THAN OR EQUAL TO STATED SIZE
99.99
Figure 32. Cumulative size distributions for three particle types,
School Administration Building, Denver, June 14, 1974
-------
Table 21. DETAILED PHYSICAL EXAMINATION: STATE HEALTH BUILDING,
DENVER, JUNE 14, 1974
A. Quartz confirmed by dispersion staining and (-) uniaxial interference
figure. EDXRA shows only silicon and trace of Iron (from hematite).
B. Calcite confirmed by EDXRA - shows only calcium.
C. Feldspars show plagioclase twinning, refractive indices above 1.530,
EDXRA shows aluminum, silicon, calcium, sodium.
D. Hematite confirmed by high refractive indices, birefringence, and deep
red color. EDXRA shows only iron.
E. Mica confirmed by crystal optics. Refractive indices and platy habit,
showing biaxial interference figure (centered) with small 2V and
negative optic sign. EDXRA shows only potassium, silicon, aluminum
and trace of iron.
F. Glassy fly ash was confirmed by its morphology and EDXRA spectrum:
showing only aluminum and silicon.
G. Rubber was confirmed by its elastomeric nature, surface appearance and
EDXRA spectrum showing mostly carbon with minor amounts of calcium,
aluminum, silicon (all probably from road wear products), sulfur,
chlorine, iron, titanium and zinc.
101
-------
TECHNICAL REPC-'ITDATA
{I'll-.'?r rend liiilfiiclions on ilif ic< ir htjaic
I POIM NO
4. TITLE ANDSUOTITLE
National Assessment of the Urban Particulate Problem;
Volume III - Denver
; AUTHORIS)
Gordon L. Deane, Frank Record, Project Director
9 PERFORMING ORGANIZATION NAME AND ADDRESS
6CA Technology Division
Burlington Road
Bedford, MA 01730
12. SPONSORING AGENCY NAMi: AND ADDRESS
U. S. Environmental Protection Agency
Office of Air Quality Planning and Standards
Research Triangle Park, North Carolina 27711
3 RECIPIENT'S ACCESSION-NCI
5 REPORT DATE
June 1976
6 PERFORMING ORGANIZATION CODt
8 PERFORMING ORGANISATION REPORT N.
GCA-TR-76-25-G(3)
10 PROGRAM ELLMLNTNO
11 CONTRACT/GRANT NO
68-02-1376
13. TVPC OF RCPORT AND Pt RIOD COVERED
Final
1-1 t.P'ONSOHING Alii Nl'Y Clint'
is. SUPPLEMENTARY NOTLS Volume I, National Assessment - EPA 450/3-76-024; Volume II,
Particle Characterization - EPA 450/3-76-025; Volumes III-XVI, Urban Area Reports
EPA 450/3-76-0263 thru J26n.
16 ABSTRACT
This document is one volume of a sixteen-volume report presenting an overall
assessment of the particulate problem, which was conducted by GCA/Technology
Division for EPA.
This particular document is one of fourteen single-area volumes that provide
working summaries of data gathered in the fourteen urban areas studied. These
city reports primarily provide documentation and background information for
Volume I of the study - National Assessment of the Particulate Problem - Final
Report. Volume I should be considered the primary output of the report.
7.
KIIY WORDS AND DOCUMENT ANAl YtJIS
Or.SCRIPTORS
Particulate Matter
Total Suspended Particulate
Emission Sources
Control Methods
Air Quality Measurements
h IDFNTIFIERS/OPF N I NDfcD Tl flMS
"Optical Wfcrbscdpy"
Secondary Particulatcs
Fuel Combustion
Process Emissions
Fugitive Emissions
Fugitive Dust
Monitor Siting
Meteorology
i COSA II Held/Group
B. DISTRIBUTION STATEMENT Release Unlimited.
Available for a fee, Thru the National
Technical Information Service. 5285 Port
Rfwal Rnari. SnHnofJPld. VA
19 SECURITY CLASS f I tin He/mill
Unclassified
21 NO OF- PAGES
118
30 SbcuaiTY CLAW;
Unclassified
EPA Form 2220-1 (9-73)
102
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