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GUIDELINE SERIES
OAQPS NO. 1.2-012
(Revised 6/75)
GUIDANCE FOR AIR QUALITY MONITORING
NETWORK DESIGN AND INSTRUMENT SITING
SUPPLEMENT A
CO SITING
sue
US. ENVIRONMENTAL PROTECTION AGENCY
Office of Air Quality Planning and Standards
Research Triangle Park, North Carolina
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• CO SITING
I OAQPS #1.2-012
(REVISED 9/75)
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DRAFT COPY
TABLE OF CONTENTS
Page
I. INTRODUCTION 1
II. MONITORING OBJECTIVES 1
A. Attainment And Maintenance Of Standards 2
B. Determination Of Trends 2
C. Evaluate Results Of Control Measures 3
D. Review Of New Sources - 3
III. GENERAL NUMBER AND TYPES OF SITES NEEDED TO
DESCRIBE REGIONAL CO LEVELS 4
A. Street Canyon 5
1. Peak 5
2. Average 7
B. Neighborhood 7
1. Peak 9
2. Average 9
C. Corridor 9
D. Background 9
IV. SPECIFIC SITE CRITERIA 9
A. Street Canyon 11
B. Neighborhood 12
C. Corridor 13
D. Background 13
E. Review Of New Sources 14
1. Pre-Construction 14
2. Post-Construction 16
V. DATA REPORTING, SUMMARIZATION AND USE 16
A. Site Not Meeting Criteria 16
B. Use Of Data 16
VI. SUMMARY 17
VII. REFERENCES 20
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I. INTRODUCTION
The purpose of this supplement is to provide further
assistance in resolving questions which commonly arise in
the siting of CO monitors. The main body of the guideline
document (OAQPS #1.2-012) contains summaries of the infor-
mation provided in detail in this attachment. This supple-
ment represents the most current OAQPS position on the siting
of CO instruments and supercedes all previous guidance material
previously issued.
The most important point in this guidance is that the
location of all monitoring sites should be standardized to
the maximum extent possible. This is essential in order to
interpret data between and within cities in a meaningful way
and to develop effective and equitable control plans. For CO,
this standardization is even more important due to the nature of
the pollutant, i.e., its sources, sinks, concentration gradients
near roadways and the relative proximity of sources and receptors
It is important to note, however, that existing CO monitors
not adhering strictly to the location criteria described
herein may still be suitable for various purposes such as
the evaluation of ambient air quality with respect to stan-
dards. Only through case-by-case evaluation of the siting
criteria can definitive statements be made about a monitor-*s
suitability.
II. MONITORING OBJECTIVES
The first step in monitoring network design is to deter-
mine the objectives of the monitoring program as a whole,
and to identify specific monitoring objectives on a site by
site basis. The general location of the monitoring instru-
ment to fulfill these objectives may then be determined. The
monitoring objectives for which CO siting criteria will be
developed in this guideline are:
1. Evaluate attainment and maintenance of standards.
2. Determination of trends.
3. Evaluation of control tactics.
4. Review of new sources
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There are, however, many other important monitoring objec-
tives. Sites which fulfill other monitoring objectives
usually require such highly specific and unique site cri-
teria that they are beyond the scope of this guideline and
must be developed on a case-by-case basis. Examples are:
research into the magnitude of sources and sinks, developing
a data base for environmental impact statements, developing
a data base for health effects research and developing, evalu-
ating and refining air pollution dispersion models.
A. Attainment And Maintenance Of Standards
It can be inferred from the air quality standards
that the most important locations for air quality measure-
ments are those that combine the highest concentrations
with the greatest exposures of population. Among the more
likely locations for such a combination is the downtown street
canyon which has high traffic densities, confined spaces
between buildings, and large numbers of people present. In
the neighborhoods, concentrations may be less, but people
spend greater periods of time exposed to them. Thus, likely
types of sites are, street canyon, neighborhood and corridor.
These types of sites must of necessity be fixed and long-
term (on the order of 2 to 3 years). In areas where scheduled
events are expected to produce high traffic densities, mobile
monitors could be used. Examples of these types of activi-
ties are sporting events, entertainment extravaganzas or
an occasional state fair or circus extending over many days.
B. Determination Of Trends
Neighborhood and to a lesser extent, corridor
sites are of the most use in determining trends occurring over
a wide area. Street canyon sites often are exposed to erratic
fluctuations in emissions over relatively small areas but
may be valuable in determining trends in maximum values or
number and/or percent of time above the standards. As
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implied by the term trend monitoring, these types of sites
must remain fixed for long periods of time (4 years or longer).
C. Evaluate Results Of Control Measures
There are many possible control measures that could
be evaluated. Some are essentially region-wide, such as trans-
portation system changes or exhaust emission controls. For
these, sites characterizing neighborhood concentrations
are suitable because they will measure the results of the
controls without being unduly influenced by large, unrelated
fluctuations in local emissions. For specific, smaller scale
control measures, monitors that will characterize street
canyons or corridors affected by the control measure will be
more appropriate. The evaluation of some control measures
on this scale may only require monitoring for a limited
period of time, perhaps a week or two in different seasons.
Among such control measures are traffic engineering changes
that would improve traffic flow in a limited part of the downtown
area. Further, the types of sites used in the development of
control measures could certainly be used in the evaluation of
the effectiveness of such measures.
D. Review of New Sources
For CO, a new source review would usually pertain to
a facility, building, structure or installation which attracts
or may attract mobile source activity that results in emissions
which could threaten the ambient CO standard(s). However,
on occasion, a new industrial source that emits large quantities
of CO will have to undergo review. For such review, it is
frequently necessary to obtain a baseline estimate of 1- and
8-hour CO concentrations at the site of a proposed source.
Such estimates may then be used either in the CO screening
technique or in modeling approaches used to estimate whether
a proposed source may pose a threat to the National Air Quality
Standards (NAAQS) for CO. Generally, the most suitable type
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of station at which to obtain CO data for the review of a
new source would be one which is located at the site of the
proposed source and is likely to provide a good estimate of
urban background concentrations which are independent of the
sources operation. A monitoring site used to obtain ambient
CO data for new source review is likely to be a short term
rather than a permanent one, on the order of several weeks
to several months.
It may sometimes be of interest to locate a monitoring
station near major arterial streets servicing a new source.
Such sites are most likely to be ones which will be used to
determine the attainment and maintenance of standards or to
determine trends. In addition, such sites may sometimes be
used to provide data to validate modeling approaches.
III. GENERAL NUMBER AND TYPES OF SITES NEEDED TO DESCRIBE
REGIONAL CO LEVELS
The number of CO monitors prescribed in the minimum
2
network requirements in the Federal Register may or may not
be entirely adequate to describe CO levels in an AQCR. Total
numbers of sites should be based on the need for data but should
not, in general, be fewer than the minimum"requirements. The intent
of this guideline is not to necessarily advocate more moni-
toring sites but to stress quality of siting and operation
of existing sites. For instance, it is better to have 3 or
4 monitors, well sited and producing valid data than 10
monitors located and operated in a haphazard manner. To
this end, we are advocating standardized site exposure
criteria.
Practically, the number of monitors available to an
agency is dictated primarily by its resources. The number
of monitors and personnel available to operate them will
influence the location of these monitors. A real problem
that may arise is that, if there is a lack of personnel
to operate, maintain and calibrate these monitors at optimum
locations, some monitors may not be located to fulfill the
monitoring objectives intended.
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— 5—
Since AQCR's are so diverse in their makeup (popu-
lation, emission sources and densities, topography, climatology,
land use and transportation habits, etc.), no absolute number
of CO sites can be prescribed which is generally applicable
for all AQCR's based upon some regional characteristic. Nor
can some uniform distribution of site types be prescribed
that would be appropriate for all regions. However, we have
detailed below some general types of sites and proposed relative
priorities which should be considered in conjunction with a
particular region's ultimate monitoring objectives. These
priorities are not universally applicable to all regions and
certainly we are not recommending that if a region has 6 CO
monitors, one should be sited in each category. On the contrary,
we recommend the bulk of the CO monitoring be confined to
priority 1 and 2 type sites. Sites of lower priority, i.e.,
3, 4 and 5 are presented only to further standardize siting
criteria for those regions who, upon analyses of their own
monitoring objectives, have determined a need to monitor in
these areas. Table 1 summarizes those suggested priorities.
The types of CO sites which meet the objectives
of the monitoring program discussed previously are elaborated
below. It is recommended that these types of sites be used
whenever possible to encourage standardization.
A. Street Canyon
This site type is usually within the central
business district (CBD) in an area of congested stop and go
traffic, with relatively uniform and tall buildings (five
stories or higher) lining both sides of the street. This
type of site can be further divided into two types, i.e.,
peak and average.
1. Peak
Monitoring at this type of site is the
highest priority within the AQCR. By 'peak,' we do not mean
the actual point of maximum concentration, even though monitoring
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TABLE 1
Suggested Priorities of CO Monitoring Sites
Site Types Priority
Peak Street Canyon #1
Peak Neighborhood #1
Average Street Canyon #2
Corridor #3
Background #4
Average Neighborhood #5
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regulation (40 CFR 51.17) specify at least one site (per pollu-
tant) be located to measure maximum concentrations to which people
could be exposed. This point is difficult if not impossible to
find (at the micro-scale level) . Nor do we mean the single inter-
section or street with the maximum number of vehicles per unit
time or otherwise atypical characteristics which can not be extra-
polated to any other location of the city. We do mean one of a
number of similar highly congested street canyons where high values
are likely to occur and from which the data can be extrapolated
to a limited number of similar areas. Since this is a peak site,
an effort should be made to determine the predominately leeward
side of the street relative to the general wind flow during maxi-
mum traffic conditions (usually during the morning or evening rush
hour) and monitor on that side. Figure 1 shows a schematic of
cross-street circulation in a street canyon and identifies the
leeward side.
2. Average*
This type of site is second in priority and should
typify the exposure to which the average commuter, pedestrian,
shopper in the CBD may be subjected. The site should typify
those areas of average traffic count, congestion and building
height. At an average street canyon site, no special pains are
necessary to determine the predominately leeward side of the
street during maximum traffic flow, but merely let convenience dic-
tate on which side of the street to monitor.
B. Neighborhood
This type of site is representative of those areas of
uniform land use (residential and commercial, etc.) away from
street canyon effects, in which a captive population i.e., the
worker, resident, or invalid is exposed. This is a longer term
exposure compared to the commuter and shopper in the street
canyon. This type of site is also divided into two types, peak
and average.
This term 'average' is not meant to suggest that data from
different stations be averaged together or combined. Data from
each station should be treated separately.
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MEAN
WIND ,
(u)
BACKGROUND
CO CONCENTRATION
(Cb)
TRAFFIC
LANE
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Figure 1-6. Schematic of cross-street circulation in street canyon
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1. Peak
This type of site shares top priority with
the peak street canyon classification. It is the area away
from localized street canyon and major traffic arterial (z 50,000
vehicle per day (VPD)) effects. It is where the concentrations
to which a large portion of the population may be exposed,
are expected to be the greatest.
2. Average
This site is similar to the peak neighbor-
hood site except the expected concentrations would be lower
and more representative of those that the majority of the
population of a region would be exposed. Data from this
type of site could be extrapolated to other neighborhoods
of similar characteristics. This type of site is of fifth
or lowest priority.
C. Corridor
This type of site is intended to bridge the gap
between the street canyon site and the neighborhood site. It
is of third priority and intended to describe those areas
in which a heavily traveled arterial, (either stop and go or
limited access) impinges upon a neighborhood. This arterial
should be greater than 50,000 VPD or the most heavily traveled
one in the AQCR if none is over 50,000 VPD.
D. Background
Here, we are talking about regional or rural back-
ground. This type of site is important as it provides a noncon-
trollable or natural base line value used in the development of
control strategies for attainment and maintenance of ambient air
standards. This type of site is listed as priority #4.
IV. SPECIFIC SITE CRITERIA
The site criteria contain specific recommendations con-
cerning such things as spacing between monitors and sources
or the heights of inlets and are summarized in tabular format
in the summary section. The recommendations have been
derived through a variety of methods. In most cases, a
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priori judgment is required during some phase of the process.
The objective of this section is to make these a priori judg-
ments as recognizable and consistent as possible. This section
presents the reasoning and judgments that were used to arrive
at the recommendations.
In some cases, such as the recommended heights of inlets,
the choices are straightforward. The importance of population
exposure to CO concentrations demands that the air be sampled
at average breathing heights. However, practical factors,
like prevention of vandalism and the potential obstruction
to pedestrians, require that the air samples be higher--
hence, the recommended 3 m which is an admitted compromise
between these two requirements. The recommendation of a
range of heights (+ ^ m) about 3 m is also a compromise bet-
ween the spatial variability of CO concentration with height
and the practical considerations involved in physically
locating a monitor.
Similarily, the recommended spacing, or setback distance,
between sites and specific sources is clearly understandable
if it is restated in terms of the expected maximum contributions
of the source to the measured CO concentrations at the site.
Thus, we have decided on acceptable levels of the interference
by a specific source (for the purpose of this guideline, 1 ppm
was selected) and proceeded to find the minimum spacing between
the source and the monitoring site where that level is not likely
to be exceeded.
Some of the procedures require other kinds of justifi-
cation. For instance, potential street canyon sites are
identified on the basis of traffic on the streets in the
area. The recommended procedure uses traffic volumes
as a surrogate for CO emissions and CO concentrations. The
reasons for this and other recommendations are discussed
further in the Stanford Research Institute report on CO
monitoring.
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By spelling out the reasoning and the assumptions behind
the choices that have been made, it should help others to make
rational decisions in cases where the requirements of their
situation are not covered by the recommendations of this guideline,
A. Street Canyon
It is recommended that inlets for street canyon
sampling should be near mid-sidewalk, at least 2 meters from
the side of a building and at a height between 2.5 and 3.5 m.
The choice of 3 m for the median height has already been
explained as compromise between average breathing height and
prevention of vandalism.
The recommended 1 m range of heights is also a
compromise to some extent. For purposes of consistency and
comparability, it would be desirable to have all inlets at
exactly the same height, but practical considerations will
often prevent this. Therefore, some reasonable range has
to be specified and 1 m should be adequate leeway to meet
most requirements.
The variability of CO concentration with height
in a street canyon is sufficiently large that the representative-
ness of the measurements will be strongly affected by varia-
bility of the inlet height. Georgii et.al (1967)'* shows
vertical gradients of CO concentration from about 0.3 ppm/m
to 0.5 ppm/m in the lower levels of a street canyon. Similar
gradients were found by Ludwig and Dabberdt (1972) . The grad-
ients will depend on traffic emissions and on street canyon
dimensions, but available observations and the empirical
model presented in Appendix A of the SRI report"" suggests
that hour-average vertical gradients of 1 ppm/m are quite
possible. Aim range of inlet height then corresponds to
a range in concentrations of about 1 ppm or less. This seems
a reasonable value for measurements in this kind of environ-
ment. The reasonableness of the 1 ppm range can be subjectively
judged by comparing it to air quality standards—it is about
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Quality Control Practices in Processing Air Pollu-
tion Samples, Environmental Protection Agency,
APTD-1132, March 1973.
Guidelines for Development of a Quality Assurance
Program, Environmental Protection Agency, EPA-R4-73-028,
a through e, June 1973.
Although the discussion in this document is concerned primarily with the
six pollutants for which air quality standards have been set, and with
associated meteorological monitoring, the principles on which it is based
are equally applicable to monitoring programs directed at other pollutants.
The ultimate purpose of providing this document is to further the goal of
increasing the usefulness of, and the compatibility among the various
sources of, ambient air quality data throughout the country; the use of
this information by States and EPA Regions should lead to a more con-
sistent, more reliable national data base that will minimize the risk of
making inappropriate policy choices or of designing control strategies that
are either inadequate or unduly stringent.
This document, however, is not intended to, and indeed could not, supplant
the need for the States and Regional Offices to develop and maintain
expertise in these matters on their own technical staffs. The issues of
network design and instrument siting involve difficult tradeoffs between
air quality information needs and available resources, and between demands
for data representativeness and instrument site availability. There is
no reasonable way that specific guidance covering all the possible aspects
of these complex tradeoffs can be provided in detail by a document of this
type. On the other hand, it is equally clear that the compatibility of the
resulting data requires a large degree of adherence to some consistent set
of guidelines, so that the practical, close-at-hand problems with re-
sources and site availability do not totally dominate the necessary
decisions.
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Accordingly, this guideline document has been prepared not as a pre-
spectlve policy document, but rather as a technical document, intended to
identify the problems that typically arise in the process of network
design and instrument siting, and to offer the generally-accepted levels
of resolution of these problems. It primarily provides the technical
information required to permit the State and Regional Office personnel
responsible for these issues to make intelligent, informed decisions based
on a reasonable knowledge of the consequences.
The reader will likely note that the tone of this document implies that
much more consideration, in both manpower and monetary resources, should
be applied to the issue of siting monitoring facilities than is currently
the common practice. This is a deliberate element of philosophy under-
lying this guidance material. It is considered inconsistent to undertake
a monitoring effort involving resources in the tens of thousands of
dollars without investing the far smaller effort involved in resolving
the issues of proper siting of the monitoring instruments.
It must be emphasized that this material is guidance, to be applied with
judgment, not a set of rigid rules to be applied in isolation. If an
existing monitoring site does not meet the placement criteria contained
herein, that does not in itself mean the data from that site cannot be
used for various purposes. Rather, it merely means that consideration of
the effects of the siting must be included in the interpretation of data
from the sites. If there are valid reasons for siting a monitoring in-
strument outside the bounds recommended here, they can and should take
precedence, and sites should not be arbitrarily moved. On the other hand,
if there are no compelling reasons for the existing siting, gradual
changes toward closer conformance with the guidelines are appropriate, in
order to reduce the overall national range of variation in siting
parameters.
Because the technical information available to bring to bear on these
problems is not completely adequate, nor as quantitative as would be
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desirable, the Monitoring and Data Analysis Division of OAQPS has under-
taken an extensive program to develop more quantitative data, especially
on the effects of site exposure parameters. As this effort progresses,
and such information becomes available, this document will be expanded
and revised as appropriate.
1.1.2 Document Organization
The variety of reasons and purposes for ambient air quality monitoring
have understandably led to a variety of different types of networks
relating to one or another circumstance, each with its own special needs
and special sets of problems. To accommodate these differences as meaning-
fully as possible, this guideline considers three general types of
monitoring as distinct situations, although it is of course recognized
that there will be some circumstances where monitoring efforts fall into
gray areas between these categories. The three major types of monitoring
considered are:
• Basic, fixed, ongoing monitoring networks
• Monitoring systems around major single sources
• Monitoring for indirect source review and planning
In this categorization, a basic, fixed, ongoing network is a network
deployed throughout a significant geographical area, and intended to pro-
vide consistent, ongoing data over a period of many years. Although such
networks are labeled "fixed," this is done only in a relative sense, to
distinguish them from shorter-term special purpose efforts. The network
design and siting decisions in such a network are not immutable; and in
fact they must be reevaluated periodically as existing air quality patterns
become known and as new land use and population growth and development
occurs. In contrast to the basic, ongoing network, the other two types
of networks are generally developed for specific shorter-term purposes,
and are usually much more intensive in both time and space. Each is
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intended to monitor the air quality impact from a specific source, rather
than the overall air quality from a receptor viewpoint.
Monitoring for such purposes as transportation control planning and air
quality maintenance planning, which are basically components of the on-
going implementation planning process, require essentially ongoing
monitoring efforts, and hence are considered part of the basic fixed net-
work. The fixed network may be supplemented by mobile or portable type
monitoring for short-term surveillance of the local impact of specific
control tactics.
This document discusses the objectives of monitoring, in the context of
all three categories, and the way in which the careful definition of
objectives can assist in making the necessary design and siting decisions,
and then considers the first of the three major categories of monitoring
listed above, the basic fixed network. Supplement A contains additional
detailed guidance on CO siting, summaries of which are contained within
this volume. Supplement B, which is still in preparation, will present
a discussion of monitoring around isolated point sources.
1.2 MONITORING OBJECTIVES
1.2.1 Definition of Objectives
It is generally agreed that the design of an ambient air quality monitoring
network should ultimately depend on the purpose of the network; that is,
on the reasons for which the monitoring is to be conducted, or the pur-
poses which the data are intended to serve. Although this is a commonly
stated goal, its implementation in practice has generally been difficult.
When considered carefully, this difficulty is usually seen to result from
variations in the detail with which the objectives are specified. The
clear, policy-oriented goal that is provided by the Clean Air Act, for
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instance, is usually too general to be of specific help in planning
monitoring operations, while the specific questions like "How many times
do the ambient levels exceed the standards?" frequently seem too prosaic
or too narrow to be considered "objectives."
In order to clarify this difficulty, and to provide a framework within
which our thinking about monitoring objectives might be structured, it
is proposed that monitoring objectives can be conveniently and accurately
thought of as occurring in three levels of detail:
• Fundamental goal of monitoring
• General monitoring objectives
• Detailed requirements of data base
1.2.1.1 Fundamental Goal of Monitoring
The basic, fundamental goal of ambient air quality monitoring efforts, as
with other air pollution control efforts, is the protection of human
health and welfare under the Clean Air Act. Since this is far too general
to be of specific help, more definitive objectives have been stated as
EPA regulations, and in further guidance, such as this document. All
this other information, however, is still rooted in the basic purpose
of the law, which should not be overlooked in the process of making net-
work design decisions.
1.2.1.2 General Monitoring Objectives
This category includes those statements about the purpose of monitoring
that are derived from the basic fundamental goal, but which are not de-
tailed specifications of needed data. They are derived from the basic
goal in the sense that they represent judgments about what is required to
protect human health and welfare in an operational sense. These objec-
tives are typically most relevant to the decisions on the station-location
aspects of network design, as opposed to the more detailed data
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specifications, which are more relevant to decisions on sampling frequency
and other operating parameters of the network. The list in Table 1-1 il-
lustrates the level of definition meant to be associated with this
category; it includes the objectives of this type that are believed to be
widely meaningful on a national scale.
Table 1-1. GENERAL MONITORING OBJECTIVES
• Provide data for research
• Provide data for air quality planning efforts
• Provide data for emergency episode prevention
• Monitor time trends and patterns
• Monitor source compliance with regulations
• Ascertain attainment and maintenance of NAAQS (population exposure)
• Determine impact of specific proposed or constructed facilities or
source concentration
• Provide data to support enforcement actions
1.2.1.3 Detailed Requirements of Data Base
The most detailed type of monitoring purposes are those that specify the
precise data needed for a specific purpose; e.g., "the number of days
particulate levels exceeded the 24-hour standard." These detailed
specifications of data requirements, when they can be precisely estab-
lished, are of great value for planning purposes; primarily for
planning the operational aspects of a network rather than the overall
configuration or instrument siting aspects. In general, these data needs
will differ with the pollutant under consideration, and they may well
differ with the changing nature of the pollution problems from one part
of the country to another or from one AQCR to another.
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1.2.2 Typical Monitoring Objectives
It is apparent that in general it is the monitoring objective, the second
level of detail of the three above, that primarily affects the location of
sites and the placement of sensors. It is not the purpose of this document
to prescribe, as a matter of policy, what the objectives of a monitoring
program should be or what priorities various objectives should have. How-
ever, some discussion of typical objectives and the structures into which
they fall is necessary in order to illustrate the way in which the general
objectives are refined into more specific decisions with respect to
monitoring sites and the way in which careful consideration of these ob-
jectives can assist in the determination of definition of specific data
needs.
One useful structure that includes the objectives in Table 1-1 can be de-
veloped by considering various combinations of the location, or orienta-
tion, of a monitoring effort and the intended use of the data from that
effort; this matrix-type structure is presented in Table 1-2. Clearly, a
monitoring site can be primarily directed at pollutant sources, at pol-
lutant receptors (population), or at a background situation where neither
sources nor population is generally present, although for some purposes
this three-way classification might be usefully subdivided.
The subdivision on the other dimension of the matrix in Table 1-2, the sub-
division of data uses into compliance, trends, and planning, is somewhat
less clear-cut. To focus on the essentials of station placement, the three
categories were defined on the basis of the fundamental conceptual require-
ments made of the data by each intended use. Thus, attainment and mainte-
nance of standards involves primarily the absolute magnitude of the re-
sulting data, while trend evaluation requires only that the data be
consistent over time. Most planning purposes require in addition, joint
information over various spatial points or for several pollutants.
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Table 1-2. MATRIX OF MONITOR ORIENTATION AND DATA USES
Data uses
Standards
attainment
and
maintenance
Trends
Air quality
planning
Monitor orientation
Source-oriented
Enforce property-
line regulations
Monitor control
progress trends
of grouped
sources
New source per-
mit review and
planning
Population-oriented
Peak population
exposure
Typical
population
exposure
Trends in
exposure
• Geographic pat-
tern for control
strategy
planning
Background
Control strategy
planning
Determine urban
impact
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reasoning behind the common practice of monitoring for the two pollutants
at the same sites. Similarily, the general lack of similarity among the
other gaseous pollutants indicates that each will require separate con-
sideration, rather than routinely placing all gaseous instrumentation
together.
These latter points illustrate the type of conclusions concerning network
configuration that can be drawn from various approaches to structuring the
objectives. The first four rows and to some extent the last row of
Table 1-3 are the objectives that are normally intended to be met by the
basic fixed network, the others being relevant to source-oriented networks.
Similarly, in Table 1-2, the source-oriented column would be generally
assigned to specific source-oriented networks, other than possibly an
isolated single fixed site in a heavy industrial area, which might be used
to observe air quality trends admist a complex of sources. Based on con-
sideration of these two structures, several different types of stations
(Peak, Neighborhood, and Background) have been defined for each of the six
major pollutants, primarily for purposes of discussion throughout this
document:
• Peak Station - Located at one of the points within the
Region where the highest concentrations and exposures
are expected to occur.
• Neighborhood Station - Located to typify a broad area of
uniform land use, not necessarily residential, but in-
cluding also homogeneous industrial or commercial areas.
• Background Station - Located in nonurban or rural areas
to provide information on levels of a pollutant trans-
ported into a Region.
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SECTION II
BASIC MONITORING NETWORKS
Basic fixed monitoring networks, in the context of this discussion, are
those monitoring systems that are directed at the overall, ongoing,
regional problem of guiding the federal-state-local pollution control
programs designed to attain and maintain the National Ambient Air Quality
Standards. This includes the basic network established in support of the
original State Implementation Plan, and any extensions and expansions
subsequently made in conjunction with transportation control planning,
air quality maintenance planning, prevention of significant deteriora-
tion, and so on, as these latter efforts are essentially just SIP
extensions for specific purposes.
The ongoing development of a permanent air quality monitoring network
involves the determination of the number and location of sampling sites,
selection of appropriate instrumentation, determination of the frequency
and schedule of sampling, and establishment of instrument and probe siting
criteria. These four basic elements of any air quality monitoring net-
work are discussed separately in subsequent portions of this section.
2.1 DESIGN OF THE NETWORK CONFIGURATION
The configuration of an air quality monitoring network involves two ele-
ments: the number of sensors or sampling sites of various types, and
their geographical location. Under differing circumstances, decisions
on the two elements can be made in either order; an overall number of
sensors or sites may be selected, based on a criterion such as resource
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availability, and then distributed geographically, or specific sites may
be selected first, based on a criterion such as the need for the data,
with the aggregate number of sites then being just the total number of
sites selected. In the past, and to some extent still at the present
time, the first approach has been necessarily taken, and approaches to
determining network size are discussed herein. In the longer term,
however, it is considered appropriate that actual data needs be the ulti-
mate determinant of network size, and that the availability of resources
should affect only the speed with which that ultimate size is reached.
With this approach, one considers the various requirements of the network,
establishes sites to provide the required data, and lets the size of the
network be whatever it turns out to be. In this way, the relevant param-
eters of the area - the overall size, the distribution of "unique" pockets
of sources and receptors, the topography, etc., - are all taken into
account.
2.1.1 Network Size
Historically, when the national control effort under the Clean Air Act
began, emphasis was on developing not only new networks but also the
resources, both manpower and monetary, to support them. Consequently, it
was necessary that networks be sized directly or indirectly in relation
to the resources available, and the sites then distributed with as much
consideration of sources, topography, etc., as was possible.
The Environmental Protection Agency Regulations (40 CFR 51.17) detailing
the requirements for a State Implementation Plan include specification of
a minimum number of monitoring sites in the AQCR as a function of the
AQCR population and the priority classification assigned to it for each
criteria pollutant. Population is a meaningful index for determining the
number of sites because geographic area, fuel use, industrial capacity,
and many other relevant parameters which affect air quality are roughly
correlated with population.
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These minimum regulatory requirements are tabulated in Table II-1; they
are designed to meet the bare minimum essential requirements of a net-
work, in the context of the resource situation of the early 1970's. It
is generally recognized that, in the present context, these minimum
requirements are not adequate in every urban area or AQCR, nor are they
necessarily adequate for proper conduct of those implementation planning
responsibilities that have arisen since the original SIP planning pro-
cess. For example, in some AQCR's carbon monoxide and oxidant monitoring
is inadequate for control planning purposes, and the geographical extent
of monitoring in relatively unpolluted areas is inadequate for use in
air quality maintenance planning.
As was indicated above, the ultimate determination of a monitoring net-
work configuration should be made on the basis of data needs to meet
specified monitoring objectives, rather than on the basis of any prior
determination of the number of sensors to be included. However, recog-
nizing that for at least the next several years, resource availability
MI 11—continue to operate as a^onstraint^ A reallocation of network
facilities may be more feasible than an increase in network size.
Redistribution of instruments from densely monitored urban core areas
to sparsely monitored suburbs and rural areas, necessitated by non-
degradation and air quality maintenance area considerationsmay be needed.
Trade-offs between too much monitoring in some areas, such as TSP and
S02, and too little monitoring for pollutants like ozone and CO may need
to be considered in the light of budgeting requirements. However, the
monitoring budget should not be the overriding factor. For example, the
resources required to establish and operate additional CO and oxidant
stations should be considered not in isolation, but rather in light of
the resources required to develop, promulgate, and implement (and possibly
litigate) a state implementation plan based on the data developed.
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2.1.2 Factors Influencing Network Design
The factors that are typically involved in estimating an adequate network
size are of course also the factors involved in designing an ultimate
network configuration as well, primarily climatological and topographic
factors. These factors are typically cited as meaningful in network
design, but it is frequently difficult to make practical use of them.
This is because they are significant primarily in the extremes, as noted
below, rather than in the broad middle range prevalent throughout most of
the country.
2.1.2.1 Meteorology and Climatology - The meteorological factors that
have the greatest effects on ambient pollution concentrations are the
horizontal wind (speei and direction, and the vertical distribution of
both) and the vertical mixing structure (stability, mixing heights). At
most locations, however, these parameters vary significantly over time
scales in hours and distance scales in tens of meters. Thus, while they
are of significance in a number of air pollution areas, they are not of
much help in the design of networks, which depends on longer-term average
parameters.
Dilution climatology is defined as the long-term average combination of
those meteorotogical conditions that affect the interchange and disper-
sion of pollutants over relatively large areas and long time intervals.
These factors, the frequency, persistence, and height variations of wind
speed and direction, of stable (inversion) layers of air, and of mixing
heights, collectively provide a measure of the dilution climatology of
an area. Dilution climatology accounts for the effects of large scale
topographic features, such as large bodies of water and mountain ranges,
that exert their influence at that scale. The relative frequency of
recurrence of short-term phenomena such as stagnation episodes is also
considered. Small scale obstructions such as hills and buildings are
classified as localized influences and are not considered in dilution
climatology. Atmospheric areas possessing similar dilution climatologies
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have been defined on a geographic basis for the contiguous United States.
They are illustrated in Figure II-l and described in Table II-2; interim
definitions for areas outside the contiguous United States in which
AQCR's have been designated are also included in Table II-2. Figure II-2
presents isopleths of mean annual solar radiation which, in conjunction
with the dispersion characteristics of the various atmospheric areas,
relates to the potential for formation of photochemical pollutants.
As was noted above, these climatological factors are of primary signifi-
cance in the extremes. The Great Plains Area has frequent high winds
which, coupled with the nature of the fuel use patterns, reduces concern
with SCL; however, because of increased fugitive dust entrainment, par-
ticulate problems require increased concern. Considering north-to-south
variations in solar radiation, it is apparent that the Southwest and the
Gulf Coast will have an accordingly greater concern with photochemical
oxidant levels.
2.1.2.2 Topography - The dispersion patterns in some sectors of an Air
Quality Control Region can be significantly altered by local topographi-
cal factors. The most significant with respect to their influence on a
monitoring network are:
Valley Effects - Valleys tend to channel the wind flow
along their axis, restrict horizontal dispersion, in-
crease the tendency for inversions to form, and may
cause aerodynamic downwash from stacks not extending
above the valley walls. "Air quality discontinuities
between valley-ridge sectors often exist. Thus, val-
leys almost always need monitors in ;excess of the
requirement for level terrain.
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Table 11-2. ATMOSPHERIC AREAS OF THE UNITED STATES
Atneaphcrlc area
California-Oregon coastal area
Washington coastal area
Kocky Kountain area
Great Plaint area
Great Lakes Northeast area
Appalachian area
Extent of area
Extends about 20 to 50 nlles Inland fro
the Pacific Ocean.
Extends »bout 20 to 30 miles Inland from
the Puget Sound region, fron vhlch
the eastern boundary extends south-
westward to the vicinity of Longvlew
on the Columbia River and then west-
ward to the coast.
Extends eastward froa the California
Oregon and Washington coastal areas to
terminate as a north-south oriented
eastern boundary, essentially core-
•ponding to the 3,000 to -*,000 toot nean
•ea level contour interval which In gen-
eral defines the eastern cost extension
of the major countaln ranges. This
eastern boundary stretches froa the
Canadian border In Montana souch-
vard through extreme eastern Colorado,
eastern N
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Table II-2 (continued). ATMOSPHERIC AREAS OF THE UNITED STATES
Atmospheric araa
Kid-Atlantic eras
South Florida-Caribbean urea
Ravailan-Paciflc «r««
Alaskin facUt* KarictM araa
Alaskan Bering Harltiwa araa
Alaskan Arctic Maritime area
Continent*! araa
Extent of area
Encompasses the Atlantic coastal plain
from extreme southwestern Connecticut;
Including the New York City and Long
Island region, southward to the South
Carolina border at the coastline, and
extends Inland to the Appalachian area.
Extends south from the Daytona Beach
Cedar Key line to Include tho southern
half of Florida, Puerto Rico* and the
Virgin lalands.
Includes all of the islands making up
tha State of Hawaii, and tha territoriaa
of Guam and American Samoa.
Bounded by the United States'Canada bor-
der to the southeast, the Chugateh Moun-
tain Range to the north, and the Aleutian
Range to the northwest. As auch this area
includes the Alexander Archipelago, the
coastal regions of the Gulf of Alaska,
Kodlak Island, the Alaskan Peninsula, end
the Aleutian Islands.
Bounded by the southwestern and western
elopes of mountain 'range* and the ridge
line of the Scward Peninsula. As such,
the area Includce the coastal plateaus end
volleys of the southwest and western main*
land, th« southern half of the Seward
penlnnula, and offshore islands.
Bounded by the western slopes of mountains
from the Sewflrd Peninsula northward to the
Brooks Mountain Range then eastward to
United States-Canadian border* As such,
this area includes the northern half of th*
Sewflrd Peninsula, the coastal regions to
tha north, and the, tundra region between
the Brooks Range and the Arctic Ocean.
Bounded by the inland portion of the
Alaska-Canadian border to the east and
tha previously described Atmospheric Area
boundaries to the north, south, and vest.
Meteorological and topographical
characteristics
Shallow mixing depths, leas frequent low-
level stability and higher wind speeds
are feature* of the dilution climate that
distinguish this coastal area from those
edjacent.
The climete of this area is predominantly
tropical-marine in nature. Atmospheric
stagnation is practically nonexistent;
there is a small frequency of low-level
stability; and relatively good vertical
mixing prevails.
Relatively good ventllatLon; occasional
surface-based nocturnal inversions in in-
land areas; persistent periods of •teg-
nation are rare.
Under the influanc* of Pacific M*titl*a
weather patterns; relatively good vtntlla*
tion associated with frequent storms; oc-
casional strong nocturnal Inversions way
persist throughout the daytime during thai
winter season; persistence of fuch condi-
tions is not marked, however, because of
the frequency of stortnlness.
Under the influence of Bering Maritime
weather conditions. Air Pollution cli-
matology vnrles from thst of the Pacific
Maritime area because of less frequent
storm activity and the resultant poten-
tial of greater persistence of aurfnca-
based inversions. In spite of differences,
persistent stagnations ere not frequent.
Under the influence of two, seasonally-
oriented weather conditions; continental
during the winter months when the ocean
is frozen; maritime during the warmer
months when the ocean is partially frea
of ice. Relatively high wind speeds pro-
vide good ventilation; the lack of solar
radiation in the winter end cold marItlew
winds during summer days result in the
highest annual frequency of daytime
surface-based Inversions of any of the
areas discussed here.
Under the Influence of continental
weather conditions; sheltered from mari-
time Influence by medium-to-high mountain
ranges on all sides; has the highest an-
nual frequency of nighttime, surface-
based inversions of any of the adjacent
areas; low wind speed during the winter»
combined with extremely persistent ground-
level inversions, gives this area the M>et
restrictive pollution climatology of any
Atstoapharie Area.
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• Shoreline Effects - Airflow along shorelines undergoes
frequent changes brought about by the changes in rela-
tive temperature of the air and vater. Discontinuities
and convergence zones in the dispersion patterns occur
which indicate need for monitoring beyond required
minimums.
• Hilly and Mountainous Terrain Effects - Complexities
introduced by hills and mountains include disrupted
airflow patterns, intersection of their interface by
elevated plumes, induced mechanical turbulence and more
frequent inversions in low-lying protected areas.
Hilly and mountainous terrain usually increase the need
for monitors.
In general, these concerns are greatest in the case of SC^ and particu-
lates which are often dispersed from major point sources. They are of
lesser importance for automotive pollutants such as CO, or secondary
pollutants like CL and N0».
2.1.3 General Patterns of Basic Networks
The overall configuration of a basic fixed network is primarily a function
of the purpose of the monitoring and the typical spatial distribution of
the pollutant under consideration. It is important to initially design a
separate network for each pollutant under consideration, and only then to
consider whether and to what extent the networks may be combined, with
sensors at common sites. The following sections consider each pollutant
in turn, discussing the configuration of networks as they typically exist
and suggesting changes as appropriate.
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2.1.3.1 Sulfur Dioxide - The general configuration of a typical sulfur
dioxide network is one of roughly uniform distribution over the built-up
or populated portion of a Region, usually with a decreasing density in
the areas farther from the urban center. One or more of the sites is
usually in the area of anticipated maximum levels, to monitor for the
attainment and maintenance of NAAQS, while the others serve to monitor
the exposure in neighborhoods (residential, downtown, commercial, etc.).
The primary goals of S02 monitoring are all relatively well-served by
such a population-oriented network with a typical site-to-site distance
of at least 2 to 4 kilometers. Typically regional 862 networks consist
of a mixture of continuous instrumentation and bubbler sites, and this
is considered appropriate; an acceptable distribution between the two
types is presented in Table II-3. The use of continuous instrumentation
at more sites than indicated in Table II-3 at all sites, is acceptable
(if somewhat expensive); the use of less continuous and more bubbler sites
is not recommended.
Table II-3. DISTRIBUTION OF CONTINUOUS AND
BUBBLER S02 INSTRUMENTATION
Number of S02 Sensors
Total
1
2
3
4
5
6
10
15
20
25
30
35
40
Continuous
0
0
0
1
1
2
3
5
7
10
13
15
17
Bubbler
1
2
3
3
4
4
7
10
13
15
17
20
23
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This overall assessment, of adequacy of S0? networks is based on the
use of emission inventories to develop S02 emission density patterns
with special consideration given to any major industrial process S02 .
source that might cause significant deviations from a relatively smooth
geographic distribution. In those few Regions with no significant S0?
emissions, relatively less dense networks are adequate.
It there are significant industrial sources, or concentrations of smaller
sources, the network should include additional sites to monitor exposures
in any adjacent residential areas. In this context, significant S02
source is intended to refer to such as refineries, smelters, etc., that
have numerous emission points. Major fuel-burning sources, such as power
plants, which have only a very few elevated emission points, should be
considered in the context of the discussions in Supplement B. A third
situation requiring a significant deviation in the density of the network
is that of unusual topography. Major topographic features, such as hills
and valleys, that destroy the smooth uniformity of air quality patterns,
require additional monitoring to define the discontinuity.
In general, current SCL state monitoring efforts are typically adequate
in comparison to the monitoring efforts directed at other pollutants. The
primary need in the near future will be for some reallocation of monitors
in the form of increased density in designated Air Quality Maintenance
Areas for S02 and around major isolated point sources, from the urban
core area or the CBD.
2.1.3.2 Suspended Particulate Matter - The general pattern of particu-
late networks is usually similar to that for S0?, in many cases consist-
ing of the same sites. This is reasonable, since the two pollutants both
have a widespread multitude of small sources, frequently the same sources.
There are, however, differences in the nature of the two pollutants that
may lead to some differences in the network configuration. Since entrain-
ment from the ground and other "fugitive dust" sources can be important
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for particulates, the issues of actual siting become of greater importance
than with S0?. In the past, a suspended particulate network that was
largely coincident with the S02 configuration was generally considered
adequate. However, as the traditionally important particulate sources
(industrial processes and fuel combustion, small coal-fired boilers) have
been eliminated or controlled, other types of sources (re-entrained urban
dust, rural fugitive emissions) have become of jajor concern. Hence, a
reallocation of monitors to neighborhood and rural sites, as opposed to indus-
trial peak sites, will be needed to understand these new problems and
develop appropriate control tactics.
2.1.3.3 Carbon Monoxide - In contrast to the case with S0? and particu-
lates, the general configuration of a typical CO monitoring network is
neither well-defined nor adequate. In most cases, CO monitoring is con-
ducted at only three or four sites in an urban AQCR. Because the measured
CO levels are very sensitive to the exact placement of the inlet probe,
the possibility of biased information resulting from this scarcity of
sites is greatly increased.
Designing a CO monitoring network is, thus, quite complicated in com-
parison to other pollutants. This is because of the nature of the NAAQS
for CO, and the differing circumstances in which they are typically vio-
lated. As there is no long-term (annual or seasonal) standard for CO,
the objective of determining trends and patterns is of a good bit less
importance, and the objective of monitoring attainment and maintenance of
NAAQS is more complicated. The issue is further complicated by the dif-
fering circumstances under which the 1-hour and 8-hour standard are typi-
cally violated, which is determined by the interaction of the strong
daily cycle in CO source strength with the seasonal and daily cycles of
atmospheric mixing potential. The 1-hour NAAQS for CO is typically vio-
lated under circumstances of maximum traffic during the morning rush hour,
often on mornings when a nocturnal radiation inversion has persisted
until the time of the rush hours. Because they depend on having heavy
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traffic for a short period, the peak 1-hour levels typically occur near
points of major traffic volumes. In contrast, the highest 8-hour CO levels
tend to occur in the evening and overnight, and may well occur quite apart
from short-term traffic peaks. This is due primariJy to differential cooling,
down slope drainage and a general reduction in mixing height, commonly occuring
in the evenings and early morning.
It is recommended that the overall CO network configuration should involve
sites of four types which are discussed in detail and prioritized in Supplement
These types are:
• Street Canyon
- Peak
- Average
• Neighborhood
- Peak
- Average
• Corridor
• Background
As discussed in Supplement A, there is generally little likelihood of
totally defining an area's CO air quality patterns with a monitoring net-
work, because the variation in CO levels is so dramatic over such short
distances that the number of monitoring sites required would be totally
prohibitive. Rather, it is considered appropriate to monitor a few care-
fully selected neighborhood and street canyon sites. These should be
selected to typify population exposures under a variety of conditions, so
that one can develop from these a relationship adequate to project the
impact in other similar areas.
2.1.3.4 Photochemical Oxidants/Ozone - The typical configuration used
for oxidant or ozone monitoring has been too often only one site in the
urban center of an AQCR, and frequently the precursor pollutants are mon-
itored at the same site. Because oxidant, as a secondary pollutant, is
not closely related to any geographic source pattern, oxidant levels have
been presumed to be relatively uniform over large areas, and one downtown
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sampling site was not considered too grossly inadequate. This is not neces-
necessarily the wisest practice, however, due to the scavenging effect of
freshly generated NO from mobile sources. Figure II-3 presents the typical
diurnal afctern experienced at such a combined site. The maximum oxidant
levels are not coincident in time with the peak levels of the precursors
and hence are not likely to be coincident in space either. This leads to
the recommendation that peak sites be located 15 to 25 km from the center
of the city in at least two general directions. These two general areas
should be selected based on wind directions during the ozone season. This
season varies, according to local climatology, from May to September in the
North to April to October in the South. Generally, ozone levels above the
NAAQS are not found when daytime ambient temperatures are below 15°C (60°F).
Consideration may well be given to reduced operation of isolated 03 monitors
during the winter months.
In addition to these peak sites, several neighborhood sites may be necessary
for monitoring population exposures in residential, commercial, and downtown
areas, depending on the population and size of the Region. For purposes of
determining possible transport of ozone into the region, it may be necessary
to have sites in remote areas upwind.
2.1.3.5 Nitrogen Dioxide - Nitrogen dioxide has a dual role in air pollu-
tion, so that two different sets of network needs must be considered. There
is an NAAQS for N02, so that peak and neighborhood population exposure must
be monitored. Because of the lag time indicated in Figure II-3, the peak
N02 exposure will not necessarily be at major traffic points of high NO
emissions. However, the timing of the peak can vary significantly through
the year (Figure II-4), so that it does not provide a very rigorous
guide for placing sites. In general, in areas where levels exceed the
standards, a population-oriented network involving both bubbler and con-
tinuous monitoring should be done in peak areas, while the intermittent
monitoring should be at neighborhood and background sites. The peak sites
should be located similar to the peak ozone sites, except that they should
be only 10 to 15 km from the center city.
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CM
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8
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0.10
0.05 -
0.10
0.05 -^
0.10
JANUARY N0
-T-|--T -i -1 ir r
1 ' ' ' ' I I
FEBRUARY
0 I i i i i i I i i i i i I i i i i i I i i i I I 1 0 !__!—LJ—!_!_!_!
i i i t t i i i i i
I I I I I I I I I I ' I ! ^ I I I I I -J J 1_1
6pm. 12
NOVEMBER NO
' i i i i i i i I L_t_i i ' i i i i ' i i '
12 60 m. 12 6pm 12
DECEMBER
12 60 m
60. m. 12 6p.m. 12
HOUR OF DAY. EST
Jiil—i I. i i—i i i. I i i i i i I i i i i i
12 6o.m. 12 6p.m. (2
HOUR OF DAY, EST
Figure II-4. Seasonal differences in NO and N02 peaks
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2.1.3.6 Nonmethane Hydrocarbons and Nitric Oxide - The existing monitoring
of nonmethane hydrocarbon and nitric oxide is typically a very limited
effort with one or a few continuous sites in an area. Since there are no
NAAQS, population-oriented monitoring is not necessary and in most areas
is not conducted.
However, data on both NO and nonmethane hydrocarbons are required along
with N02 and oxidant data to provide research and planning information with
respect to photochemical oxidant reduction. Single sites at the urban
center are clearly not adequate for this purpose, as they do not permit any
resolution of spatial distribution and transport-reaction time questions.
It is recommended (although not required) that hydrocarbon and paired NO
X
sensors be located in the CBD of the urban core area when reliable instru-
ments for measuring non-methane hydrocarbons become available.
2.1.3.7 Meteorological Sensors - In addition to data on pollutant concen-
trations, it is necessary to have available some source of meteorological
data for use in dispersion modeling and other data analysis efforts utiliz-
ing the monitoring network data. The data should include wind speed, wind
direction, and vertical stability information, although most networks
include only wind speed and direction, since vertical temperature param-
eters are difficult to monitor in urban areas.
Wind data may often be adequately supplied by the National Weather Service
or by commercial consultants. In other cases, however, the National
Weather Service airport site may be too remote, or the data otherwise less
than adequate, and wind speed and direction sensors should be included in
the air quality monitoring network. Such sensors, if included, should be
placed at sites where several continuous instruments are housed together,
in order to obtain the greatest use of the data for modeling and research
purposes. An adequate number of meteorological sensors would probably be
on the order of one-half or less of the number of such stations.
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Information on vertical stability can usually be adequately obtained in-
directly by utilizing inferred relationships between wind conditions, time
of day, insolation and vertical stability classes. Observations of temper-
ature at several heights near the surface are very useful to infer stability
for short-term modeling and air quality forecasting, but extensive measure-
ment of vertical parameters is usually only done on a research basis.
2.1.3.8 Combined Sites - As has been noted above, it has been common prac-
tice to consider the configuration of an entire network covering all pol-
lutants, as a whole rather than on a strict pollutant-by-pollutant basis.
This is, of course, done as a matter of economy, both of cost and manpower,
it generally being more economical to have as many sensors collected at
one site as possible.
It is considered appropriate to combine instruments to a certain extent.
However, it is not appropriate to routinely house all instruments for all
pollutants together as has often been common practice, except for back-
ground sites.
The peak and neighborhood type sites for total suspended particulate and
SO™ may very reasonably be combined. As was noted, it is specifically
recommended that in the case of research and planning sites, hydrocarbon
and oxides of nitrogen sensors be collected together together into sta-
tions, which may also reasonably include hi-vols and S0£ sensors.
However, as also noted above, the locations of peak levels of the various
pollutants are in most cases not at the same location within the area.
Most prominent example of this is carbon monoxide. Although it is obvi-
ously convenient to have all the continuous sensors together, it is
extremely rare to find a site large enough for a full monitoring station
that is also in an appropriate location for peak CO monitoring and,
indeed, sites suitable for CO monitoring are not necessarily suitable for
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other pollutants, depending on the purpose. Hence it is not prudent to
presume that CO sensors can be located with the others, although if pos-
sible of course it should be done.
2.1.4 Ad d i ti ona1 Quid ance
Other recent and current EPA contract efforts relevant to the issues of
network design, optimization, and evaluation include:
Guidelines for Air Quality Maintenance Planning and Analysis,
Volume 11; "Air Quality Monitoring and Data Analysis"
Subject Matter; This document provides states with
planning information and guidance for the preparation
and implementation of a monitoring system which is
compatible with the goal of air quality maintenance
and the need for the development of Air Quality Main-
tenance Plans.
Status; The guideline document (also identified as
EPA-450/4-74-012 and OAQPS #1.2-030) has been completed
by the GGA Corporation, September 1974.
EPA Project Officer: Alan J. Hoffman, MRB, HDAD, OAQPS.
Collection and Integration of Operational Characteristics of
Existing Pollutant Monitoring Networks
Subject Matter; This study deals with the analysis of
operational data gathered from five superior air and
water monitoring networks to identify the most efficient
and economical methodology by which a monitoring network
can satisfy its responsibilities and optimize the cost-
effectiveness of daily operations. The goal of the pro-
ject is the development of manuals that would furnish
the desired techniques for evaluating operations, and to
provide methodologies by which the efficiency and/or
cost-effectiveness of all operations could be readily
considered along with the effects of alternative actions
where the evaluation indicates that improvement is needed,
while remaining within budgetary constraints and meeting
network objectives.
Status; The project is being carried out by URS Research
Corp. and is expected to be completed by November 1975.
EPA Project Officers: Edward A. Schuck and
Leslie Dunn, MSA, NERC-LV
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2.2 INSTRUMENT SITING AND PROBE EXPOSURE
After the general location of a sampling site is selected, based on con-
sideration of the Region-wide configuration, it is necessary to select a
site for the sensor or station, and then within the confines of that
choice to determine the precise location of the inlet probe in the case
of gaseous pollutants.
2.2.1 Site Selection
The selection of a precise site, once a general area has been
selected, is primarily a question of availability, accessibility, secu-
rity, and the potential effect of surrounding structures. The issues of
accessibility and security are the ongoing concerns of the daily opera-
tion of a network, and there is little additional guidance to be offered.
The issues of ground-level versus rooftop sites might be considered a
site-selection problem, as availability is one of the primary reasons for
seeking rooftop sites; however, the impact of the choice is more in the
nature of a probe placement issue, and it is so considered here.
Sulfur dioxide is considered to be rather well mixed near the ground, at
least at receptors not overly affected by specific point sources. There-
fore, either ground or roof-top sampling is adequate, and the choice can
be made on the basis of site availability. However, care must be taken to
ensure that rooftops are 'clean,' i.e., free from space heating vents,
laboratory hood vents, and the like, that may have S02 emissions. Once above
the effect of reentrainment from the ground, it is generally considered
that TSP is also fairly well mixed for the next few hundred feet above the
ground. Hence rooftop sampling has traditionally been recommended in order
to avoid influence of possible reentrainment effect, and rooftops up to
several stories high have been used, particularly at center city sites. If
the reentrainment is to be considered, however, perhaps as part of the popu-
lation exposure, then a site that permits ground level (2 to 3 meters)
sampling is required. If such a site is not attainable, an alternate
arrangement such as a portable sampler should be considered. This is a
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clear instance where the purpose of the monitoring needs to be very
precisely stated to determine the appropriate siting action.
The obvious case where station siting depends on the purpose of the
monitoring is with CO, where a station may be either a street canyon,
neighborhood, corridor, or background station. In contrast to the case
with S02, the horizontal distribution of CO across an urban area consists
of so many alternating areas of peak and valley levels, one at each
street or major traffic center, that one must consider site locations
for CO primarily in probe placement terms, in scale of plus or minus a
meter or two. Hence a peak station site needs to be essentially adja-
cent to the street in question and needs to permit nose-level sampling,
while a neighborhood site must be located at least 35 meters from the
nearest street. This setback will limit the influence of the nearest street
to about 1 ppm and make the reading more representative of the general
community in which the monitor is located. The strong dependence of carbon
monoxide concentration upon distance from the nearest roadway has been
illustrated in a number of studies. ' Generally it was found that the
concentrations experienced by pedestrians exceeded those measured at a
typical air monitoring site, while concentrations at randomly selected
locations throughout the survey grid were less than those at the site.
More specifically, the data in one study indicated that average concentra-
tions determined by the monitor would be reduced to near the urban back-
ground level by moving the monitor approximately 200 feet farther back
Q
from the street. Figure II-5 indicates how the CO levels at the various
stations in Los Angeles are closely related to the slant distance from
the street, despite presumably different traffic volumes in the various
locales. It is also known that for peak CO sampling within street canyons,
the side of the street which is opposite the side facing the rooftop-level
winds will experience the higher concentrations (see Figure II-6). Hence
in any location with a significantly prevailing wind direction, even the
choice of the side of the street becomes a relevant siting question.
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BACKGROUND
CO CONCENTRATION
PRIMARY RECEPTOR
VORTEX
TRAFFIC
LANE
-W-
Figure II-6. Schematic of cross-street circulation in street canyon'
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2.2.2 Probe Placement
Within the several meters scale involved in a typical monitoring site,
there is general latitude in the precise placement of the inlet probe.
For the gaseous pollutants (excepting CO), this is an issue primarily
involving security from vandalism, the avoidance of any restrictions
to the air flow, such as from the station itself, trees, etc., and any
undue influence from a minor local source, such as a stack located on
the roof of a building where the air inlet is located. These require-
ments are generally taken to indicate a height above the ground of 3
to 15 meters, and either a vertical clearance above the roof of 1 to
2 meters or, in a different configuration, a horizontal clearance
beyond the supporting structure of at least 2 meters.
In the case of particulates, the hi-vol represents a special situation.
Historically, the NA.SN hi-vols have been on rooftops, sometimes 8 to
10 stories high. This avoids reentrained surface dust, and the atten-
dant variability, and in so doing provides a smoother, more reliable
record for trend purposes. However, it can be argued that elevating
the sampler in this way makes the resulting data an inaccurate reflec-
tion of true population exposure. Table II-4 provides, as an example,
a comparison of 5 months' data from the CAMP Station in Philadelphia
and the Franklin Institute site operated by the Philadelphia Department
of Public Health. The CAMP Station hi-vol, at 11 feet, reads consis-
tently higher than the City Station, at the same location, which is at
about 50 feet. It is probably also true, though perhaps less thoroughly
demonstrated, that the distance of the hi-vol from a nearby street is of
importance. Since streets, walkways, and other such areas are a source
of reentrained particulate matter, it is probable that placing a hi-vol
on a one-story roof, for instance, is not the same as placing it in an
open area or on a trailer, even if the height above the ground is the
same.
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Quality Control Practices in Processing Air Pollu-
tion Samples, Environmental Protection Agency,
APTD-1132, March 1973.
Guidelines for Development of a Quality Assurance
Program, Environmental Protection Agency, EPA-R4-73-028,
a through e, June 1973.
Although the discussion in this document is concerned primarily with the
six pollutants for which air quality standards have been set, and with
associated meteorological monitoring, the principles on which it is based
are equally applicable to monitoring programs directed at other pollutants.
The ultimate purpose of providing this document is to further the goal of
increasing the usefulness of, and the compatibility among the various
sources of, ambient air quality data throughout the country; the use of
this information by States and EPA Regions should lead to a more con-
sistent, more reliable national data base that will minimize the risk of
making inappropriate policy choices or of designing control strategies that
are either inadequate or unduly stringent.
This document, however, is not intended to, and indeed could not, supplant
the need for the States and Regional Offices to develop and maintain
expertise in these matters on their own technical staffs. The issues of
network design and instrument siting involve difficult tradeoffs between
air quality information needs and available resources, and between demands
for data representativeness and instrument site availability. There is
no reasonable way that specific guidance covering all the possible aspects
of these complex tradeoffs can be provided in detail by a document of this
type. On the other hand, it is equally clear that the compatibility of the
resulting data requires a large degree of adherence to some consistent set
of guidelines, so that the practical, close-at-hand problems with re-
sources and site availability do not totally dominate the necessary
decisions.
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Accordingly, this guideline document has been prepared not as a pre-
spectlve policy document, but rather as a technical document, intended to
identify the problems that typically arise in the process of network
design and instrument siting, and to offer the generally-accepted levels
of resolution of these problems. It primarily provides the technical
information required to permit the State and Regional Office personnel
responsible for these issues to make intelligent, informed decisions based
on a reasonable knowledge of the consequences.
The reader will likely note that the tone of this document implies that
much more consideration, in both manpower and monetary resources, should
be applied to the issue of siting monitoring facilities than is currently
the common practice. This is a deliberate element of philosophy under-
lying this guidance material. It is considered inconsistent to undertake
a monitoring effort involving resources in the tens of thousands of
dollars without investing the far smaller effort involved in resolving
the issues of proper siting of the monitoring instruments.
It must be emphasized that this material is guidance, to be applied with
judgment, not a set of rigid rules to be applied in isolation. If an
existing monitoring site does not meet the placement criteria contained
herein, that does not in itself mean the data from that site cannot be
used for various purposes. Rather, it merely means that consideration of
the effects of the siting must be included in the interpretation of data
from the sites. If there are valid reasons for siting a monitoring in-
strument outside the bounds recommended here, they can and should take
precedence, and sites should not be arbitrarily moved. On the other hand,
if there are no compelling reasons for the existing siting, gradual
changes toward closer conformance with the guidelines are appropriate, in
order to reduce the overall national range of variation in siting
parameters.
Because the technical information available to bring to bear on these
problems is not completely adequate, nor as quantitative as would be
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desirable, the Monitoring and Data Analysis Division of OAQPS has under-
taken an extensive program to develop more quantitative data, especially
on the effects of site exposure parameters. As this effort progresses,
and such information becomes available, this document will be expanded
and revised as appropriate.
1.1.2 Document Organization
The variety of reasons and purposes for ambient air quality monitoring
have understandably led to a variety of different types of networks
relating to one or another circumstance, each with its own special needs
and special sets of problems. To accommodate these differences as meaning-
fully as possible, this guideline considers three general types of
monitoring as distinct situations, although it is of course recognized
that there will be some circumstances where monitoring efforts fall into
gray areas between these categories. The three major types of monitoring
considered are:
• Basic, fixed, ongoing monitoring networks
• Monitoring systems around major single sources
• Monitoring for indirect source review and planning
In this categorization, a basic, fixed, ongoing network is a network
deployed throughout a significant geographical area, and intended to pro-
vide consistent, ongoing data over a period of many years. Although such
networks are labeled "fixed," this is done only in a relative sense, to
distinguish them from shorter-term special purpose efforts. The network
design and siting decisions in such a network are not immutable; and in
fact they must be reevaluated periodically as existing air quality patterns
become known and as new land use and population growth and development
occurs. In contrast to the basic, ongoing network, the other two types
of networks are generally developed for specific shorter-term purposes,
and are usually much more intensive in both time and space. Each is
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intended to monitor the air quality impact from a specific source, rather
than the overall air quality from a receptor viewpoint.
Monitoring for such purposes as transportation control planning and air
quality maintenance planning, which are basically components of the on-
going implementation planning process, require essentially ongoing
monitoring efforts, and hence are considered part of the basic fixed net-
work. The fixed network may be supplemented by mobile or portable type
monitoring for short-term surveillance of the local impact of specific
control tactics.
This document discusses the objectives of monitoring, in the context of
all three categories, and the way in which the careful definition of
objectives can assist in making the necessary design and siting decisions,
and then considers the first of the three major categories of monitoring
listed above, the basic fixed network. Supplement A contains additional
detailed guidance on CO siting, summaries of which are contained within
this volume. Supplement B, which is still in preparation, will present
a discussion of monitoring around isolated point sources.
1.2 MONITORING OBJECTIVES
1.2.1 Definition of Objectives
It is generally agreed that the design of an ambient air quality monitoring
network should ultimately depend on the purpose of the network; that is,
on the reasons for which the monitoring is to be conducted, or the pur-
poses which the data are intended to serve. Although this is a commonly
stated goal, its implementation in practice has generally been difficult.
When considered carefully, this difficulty is usually seen to result from
variations in the detail with which the objectives are specified. The
clear, policy-oriented goal that is provided by the Clean Air Act, for
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instance, is usually too general to be of specific help in planning
monitoring operations, while the specific questions like "How many times
do the ambient levels exceed the standards?" frequently seem too prosaic
or too narrow to be considered "objectives."
In order to clarify this difficulty, and to provide a framework within
which our thinking about monitoring objectives might be structured, it
is proposed that monitoring objectives can be conveniently and accurately
thought of as occurring in three levels of detail:
• Fundamental goal of monitoring
• General monitoring objectives
• Detailed requirements of data base
1.2.1.1 Fundamental Goal of Monitoring
The basic, fundamental goal of ambient air quality monitoring efforts, as
with other air pollution control efforts, is the protection of human
health and welfare under the Clean Air Act. Since this is far too general
to be of specific help, more definitive objectives have been stated as
EPA regulations, and in further guidance, such as this document. All
this other information, however, is still rooted in the basic purpose
of the law, which should not be overlooked in the process of making net-
work design decisions.
1.2.1.2 General Monitoring Objectives
This category includes those statements about the purpose of monitoring
that are derived from the basic fundamental goal, but which are not de-
tailed specifications of needed data. They are derived from the basic
goal in the sense that they represent judgments about what is required to
protect human health and welfare in an operational sense. These objec-
tives are typically most relevant to the decisions on the station-location
aspects of network design, as opposed to the more detailed data
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specifications, which are more relevant to decisions on sampling frequency
and other operating parameters of the network. The list in Table 1-1 il-
lustrates the level of definition meant to be associated with this
category; it includes the objectives of this type that are believed to be
widely meaningful on a national scale.
Table 1-1. GENERAL MONITORING OBJECTIVES
• Provide data for research
• Provide data for air quality planning efforts
• Provide data for emergency episode prevention
• Monitor time trends and patterns
• Monitor source compliance with regulations
• Ascertain attainment and maintenance of NAAQS (population exposure)
• Determine impact of specific proposed or constructed facilities or
source concentration
• Provide data to support enforcement actions
1.2.1.3 Detailed Requirements of Data Base
The most detailed type of monitoring purposes are those that specify the
precise data needed for a specific purpose; e.g., "the number of days
particulate levels exceeded the 24-hour standard." These detailed
specifications of data requirements, when they can be precisely estab-
lished, are of great value for planning purposes; primarily for
planning the operational aspects of a network rather than the overall
configuration or instrument siting aspects. In general, these data needs
will differ with the pollutant under consideration, and they may well
differ with the changing nature of the pollution problems from one part
of the country to another or from one AQCR to another.
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1.2.2 Typical Monitoring Objectives
It is apparent that in general it is the monitoring objective, the second
level of detail of the three above, that primarily affects the location of
sites and the placement of sensors. It is not the purpose of this document
to prescribe, as a matter of policy, what the objectives of a monitoring
program should be or what priorities various objectives should have. How-
ever, some discussion of typical objectives and the structures into which
they fall is necessary in order to illustrate the way in which the general
objectives are refined into more specific decisions with respect to
monitoring sites and the way in which careful consideration of these ob-
jectives can assist in the determination of definition of specific data
needs.
One useful structure that includes the objectives in Table 1-1 can be de-
veloped by considering various combinations of the location, or orienta-
tion, of a monitoring effort and the intended use of the data from that
effort; this matrix-type structure is presented in Table 1-2. Clearly, a
monitoring site can be primarily directed at pollutant sources, at pol-
lutant receptors (population), or at a background situation where neither
sources nor population is generally present, although for some purposes
this three-way classification might be usefully subdivided.
The subdivision on the other dimension of the matrix in Table 1-2, the sub-
division of data uses into compliance, trends, and planning, is somewhat
less clear-cut. To focus on the essentials of station placement, the three
categories were defined on the basis of the fundamental conceptual require-
ments made of the data by each intended use. Thus, attainment and mainte-
nance of standards involves primarily the absolute magnitude of the re-
sulting data, while trend evaluation requires only that the data be
consistent over time. Most planning purposes require in addition, joint
information over various spatial points or for several pollutants.
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Table 1-2. MATRIX OF MONITOR ORIENTATION AND DATA USES
Data uses
Standards
attainment
and
maintenance
Trends
Air quality
planning
Monitor orientation
Source-oriented
Enforce property-
line regulations
Monitor control
progress trends
of grouped
sources
New source per-
mit review and
planning
Population-oriented
Peak population
exposure
Typical
population
exposure
Trends in
exposure
• Geographic pat-
tern for control
strategy
planning
Background
Control strategy
planning
Determine urban
impact
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reasoning behind the common practice of monitoring for the two pollutants
at the same sites. Similarily, the general lack of similarity among the
other gaseous pollutants indicates that each will require separate con-
sideration, rather than routinely placing all gaseous instrumentation
together.
These latter points illustrate the type of conclusions concerning network
configuration that can be drawn from various approaches to structuring the
objectives. The first four rows and to some extent the last row of
Table 1-3 are the objectives that are normally intended to be met by the
basic fixed network, the others being relevant to source-oriented networks.
Similarly, in Table 1-2, the source-oriented column would be generally
assigned to specific source-oriented networks, other than possibly an
isolated single fixed site in a heavy industrial area, which might be used
to observe air quality trends admist a complex of sources. Based on con-
sideration of these two structures, several different types of stations
(Peak, Neighborhood, and Background) have been defined for each of the six
major pollutants, primarily for purposes of discussion throughout this
document:
• Peak Station - Located at one of the points within the
Region where the highest concentrations and exposures
are expected to occur.
• Neighborhood Station - Located to typify a broad area of
uniform land use, not necessarily residential, but in-
cluding also homogeneous industrial or commercial areas.
• Background Station - Located in nonurban or rural areas
to provide information on levels of a pollutant trans-
ported into a Region.
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SECTION II
BASIC MONITORING NETWORKS
Basic fixed monitoring networks, in the context of this discussion, are
those monitoring systems that are directed at the overall, ongoing,
regional problem of guiding the federal-state-local pollution control
programs designed to attain and maintain the National Ambient Air Quality
Standards. This includes the basic network established in support of the
original State Implementation Plan, and any extensions and expansions
subsequently made in conjunction with transportation control planning,
air quality maintenance planning, prevention of significant deteriora-
tion, and so on, as these latter efforts are essentially just SIP
extensions for specific purposes.
The ongoing development of a permanent air quality monitoring network
involves the determination of the number and location of sampling sites,
selection of appropriate instrumentation, determination of the frequency
and schedule of sampling, and establishment of instrument and probe siting
criteria. These four basic elements of any air quality monitoring net-
work are discussed separately in subsequent portions of this section.
2.1 DESIGN OF THE NETWORK CONFIGURATION
The configuration of an air quality monitoring network involves two ele-
ments: the number of sensors or sampling sites of various types, and
their geographical location. Under differing circumstances, decisions
on the two elements can be made in either order; an overall number of
sensors or sites may be selected, based on a criterion such as resource
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availability, and then distributed geographically, or specific sites may
be selected first, based on a criterion such as the need for the data,
with the aggregate number of sites then being just the total number of
sites selected. In the past, and to some extent still at the present
time, the first approach has been necessarily taken, and approaches to
determining network size are discussed herein. In the longer term,
however, it is considered appropriate that actual data needs be the ulti-
mate determinant of network size, and that the availability of resources
should affect only the speed with which that ultimate size is reached.
With this approach, one considers the various requirements of the network,
establishes sites to provide the required data, and lets the size of the
network be whatever it turns out to be. In this way, the relevant param-
eters of the area - the overall size, the distribution of "unique" pockets
of sources and receptors, the topography, etc., - are all taken into
account.
2.1.1 Network Size
Historically, when the national control effort under the Clean Air Act
began, emphasis was on developing not only new networks but also the
resources, both manpower and monetary, to support them. Consequently, it
was necessary that networks be sized directly or indirectly in relation
to the resources available, and the sites then distributed with as much
consideration of sources, topography, etc., as was possible.
The Environmental Protection Agency Regulations (40 CFR 51.17) detailing
the requirements for a State Implementation Plan include specification of
a minimum number of monitoring sites in the AQCR as a function of the
AQCR population and the priority classification assigned to it for each
criteria pollutant. Population is a meaningful index for determining the
number of sites because geographic area, fuel use, industrial capacity,
and many other relevant parameters which affect air quality are roughly
correlated with population.
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These minimum regulatory requirements are tabulated in Table II-1; they
are designed to meet the bare minimum essential requirements of a net-
work, in the context of the resource situation of the early 1970's. It
is generally recognized that, in the present context, these minimum
requirements are not adequate in every urban area or AQCR, nor are they
necessarily adequate for proper conduct of those implementation planning
responsibilities that have arisen since the original SIP planning pro-
cess. For example, in some AQCR's carbon monoxide and oxidant monitoring
is inadequate for control planning purposes, and the geographical extent
of monitoring in relatively unpolluted areas is inadequate for use in
air quality maintenance planning.
As was indicated above, the ultimate determination of a monitoring net-
work configuration should be made on the basis of data needs to meet
specified monitoring objectives, rather than on the basis of any prior
determination of the number of sensors to be included. However, recog-
nizing that for at least the next several years, resource availability
MI 11—continue to operate as a^onstraint^ A reallocation of network
facilities may be more feasible than an increase in network size.
Redistribution of instruments from densely monitored urban core areas
to sparsely monitored suburbs and rural areas, necessitated by non-
degradation and air quality maintenance area considerationsmay be needed.
Trade-offs between too much monitoring in some areas, such as TSP and
S02, and too little monitoring for pollutants like ozone and CO may need
to be considered in the light of budgeting requirements. However, the
monitoring budget should not be the overriding factor. For example, the
resources required to establish and operate additional CO and oxidant
stations should be considered not in isolation, but rather in light of
the resources required to develop, promulgate, and implement (and possibly
litigate) a state implementation plan based on the data developed.
II-3
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2.1.2 Factors Influencing Network Design
The factors that are typically involved in estimating an adequate network
size are of course also the factors involved in designing an ultimate
network configuration as well, primarily climatological and topographic
factors. These factors are typically cited as meaningful in network
design, but it is frequently difficult to make practical use of them.
This is because they are significant primarily in the extremes, as noted
below, rather than in the broad middle range prevalent throughout most of
the country.
2.1.2.1 Meteorology and Climatology - The meteorological factors that
have the greatest effects on ambient pollution concentrations are the
horizontal wind (speei and direction, and the vertical distribution of
both) and the vertical mixing structure (stability, mixing heights). At
most locations, however, these parameters vary significantly over time
scales in hours and distance scales in tens of meters. Thus, while they
are of significance in a number of air pollution areas, they are not of
much help in the design of networks, which depends on longer-term average
parameters.
Dilution climatology is defined as the long-term average combination of
those meteorotogical conditions that affect the interchange and disper-
sion of pollutants over relatively large areas and long time intervals.
These factors, the frequency, persistence, and height variations of wind
speed and direction, of stable (inversion) layers of air, and of mixing
heights, collectively provide a measure of the dilution climatology of
an area. Dilution climatology accounts for the effects of large scale
topographic features, such as large bodies of water and mountain ranges,
that exert their influence at that scale. The relative frequency of
recurrence of short-term phenomena such as stagnation episodes is also
considered. Small scale obstructions such as hills and buildings are
classified as localized influences and are not considered in dilution
climatology. Atmospheric areas possessing similar dilution climatologies
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have been defined on a geographic basis for the contiguous United States.
They are illustrated in Figure II-l and described in Table II-2; interim
definitions for areas outside the contiguous United States in which
AQCR's have been designated are also included in Table II-2. Figure II-2
presents isopleths of mean annual solar radiation which, in conjunction
with the dispersion characteristics of the various atmospheric areas,
relates to the potential for formation of photochemical pollutants.
As was noted above, these climatological factors are of primary signifi-
cance in the extremes. The Great Plains Area has frequent high winds
which, coupled with the nature of the fuel use patterns, reduces concern
with SCL; however, because of increased fugitive dust entrainment, par-
ticulate problems require increased concern. Considering north-to-south
variations in solar radiation, it is apparent that the Southwest and the
Gulf Coast will have an accordingly greater concern with photochemical
oxidant levels.
2.1.2.2 Topography - The dispersion patterns in some sectors of an Air
Quality Control Region can be significantly altered by local topographi-
cal factors. The most significant with respect to their influence on a
monitoring network are:
Valley Effects - Valleys tend to channel the wind flow
along their axis, restrict horizontal dispersion, in-
crease the tendency for inversions to form, and may
cause aerodynamic downwash from stacks not extending
above the valley walls. "Air quality discontinuities
between valley-ridge sectors often exist. Thus, val-
leys almost always need monitors in ;excess of the
requirement for level terrain.
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Table 11-2. ATMOSPHERIC AREAS OF THE UNITED STATES
Atneaphcrlc area
California-Oregon coastal area
Washington coastal area
Kocky Kountain area
Great Plaint area
Great Lakes Northeast area
Appalachian area
Extent of area
Extends about 20 to 50 nlles Inland fro
the Pacific Ocean.
Extends »bout 20 to 30 miles Inland from
the Puget Sound region, fron vhlch
the eastern boundary extends south-
westward to the vicinity of Longvlew
on the Columbia River and then west-
ward to the coast.
Extends eastward froa the California
Oregon and Washington coastal areas to
terminate as a north-south oriented
eastern boundary, essentially core-
•ponding to the 3,000 to -*,000 toot nean
•ea level contour interval which In gen-
eral defines the eastern cost extension
of the major countaln ranges. This
eastern boundary stretches froa the
Canadian border In Montana souch-
vard through extreme eastern Colorado,
eastern N
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Table II-2 (continued). ATMOSPHERIC AREAS OF THE UNITED STATES
Atmospheric araa
Kid-Atlantic eras
South Florida-Caribbean urea
Ravailan-Paciflc «r««
Alaskin facUt* KarictM araa
Alaskan Bering Harltiwa araa
Alaskan Arctic Maritime area
Continent*! araa
Extent of area
Encompasses the Atlantic coastal plain
from extreme southwestern Connecticut;
Including the New York City and Long
Island region, southward to the South
Carolina border at the coastline, and
extends Inland to the Appalachian area.
Extends south from the Daytona Beach
Cedar Key line to Include tho southern
half of Florida, Puerto Rico* and the
Virgin lalands.
Includes all of the islands making up
tha State of Hawaii, and tha territoriaa
of Guam and American Samoa.
Bounded by the United States'Canada bor-
der to the southeast, the Chugateh Moun-
tain Range to the north, and the Aleutian
Range to the northwest. As auch this area
includes the Alexander Archipelago, the
coastal regions of the Gulf of Alaska,
Kodlak Island, the Alaskan Peninsula, end
the Aleutian Islands.
Bounded by the southwestern and western
elopes of mountain 'range* and the ridge
line of the Scward Peninsula. As such,
the area Includce the coastal plateaus end
volleys of the southwest and western main*
land, th« southern half of the Seward
penlnnula, and offshore islands.
Bounded by the western slopes of mountains
from the Sewflrd Peninsula northward to the
Brooks Mountain Range then eastward to
United States-Canadian border* As such,
this area includes the northern half of th*
Sewflrd Peninsula, the coastal regions to
tha north, and the, tundra region between
the Brooks Range and the Arctic Ocean.
Bounded by the inland portion of the
Alaska-Canadian border to the east and
tha previously described Atmospheric Area
boundaries to the north, south, and vest.
Meteorological and topographical
characteristics
Shallow mixing depths, leas frequent low-
level stability and higher wind speeds
are feature* of the dilution climate that
distinguish this coastal area from those
edjacent.
The climete of this area is predominantly
tropical-marine in nature. Atmospheric
stagnation is practically nonexistent;
there is a small frequency of low-level
stability; and relatively good vertical
mixing prevails.
Relatively good ventllatLon; occasional
surface-based nocturnal inversions in in-
land areas; persistent periods of •teg-
nation are rare.
Under the influanc* of Pacific M*titl*a
weather patterns; relatively good vtntlla*
tion associated with frequent storms; oc-
casional strong nocturnal Inversions way
persist throughout the daytime during thai
winter season; persistence of fuch condi-
tions is not marked, however, because of
the frequency of stortnlness.
Under the influence of Bering Maritime
weather conditions. Air Pollution cli-
matology vnrles from thst of the Pacific
Maritime area because of less frequent
storm activity and the resultant poten-
tial of greater persistence of aurfnca-
based inversions. In spite of differences,
persistent stagnations ere not frequent.
Under the influence of two, seasonally-
oriented weather conditions; continental
during the winter months when the ocean
is frozen; maritime during the warmer
months when the ocean is partially frea
of ice. Relatively high wind speeds pro-
vide good ventilation; the lack of solar
radiation in the winter end cold marItlew
winds during summer days result in the
highest annual frequency of daytime
surface-based Inversions of any of the
areas discussed here.
Under the Influence of continental
weather conditions; sheltered from mari-
time Influence by medium-to-high mountain
ranges on all sides; has the highest an-
nual frequency of nighttime, surface-
based inversions of any of the adjacent
areas; low wind speed during the winter»
combined with extremely persistent ground-
level inversions, gives this area the M>et
restrictive pollution climatology of any
Atstoapharie Area.
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• Shoreline Effects - Airflow along shorelines undergoes
frequent changes brought about by the changes in rela-
tive temperature of the air and vater. Discontinuities
and convergence zones in the dispersion patterns occur
which indicate need for monitoring beyond required
minimums.
• Hilly and Mountainous Terrain Effects - Complexities
introduced by hills and mountains include disrupted
airflow patterns, intersection of their interface by
elevated plumes, induced mechanical turbulence and more
frequent inversions in low-lying protected areas.
Hilly and mountainous terrain usually increase the need
for monitors.
In general, these concerns are greatest in the case of SC^ and particu-
lates which are often dispersed from major point sources. They are of
lesser importance for automotive pollutants such as CO, or secondary
pollutants like CL and N0».
2.1.3 General Patterns of Basic Networks
The overall configuration of a basic fixed network is primarily a function
of the purpose of the monitoring and the typical spatial distribution of
the pollutant under consideration. It is important to initially design a
separate network for each pollutant under consideration, and only then to
consider whether and to what extent the networks may be combined, with
sensors at common sites. The following sections consider each pollutant
in turn, discussing the configuration of networks as they typically exist
and suggesting changes as appropriate.
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2.1.3.1 Sulfur Dioxide - The general configuration of a typical sulfur
dioxide network is one of roughly uniform distribution over the built-up
or populated portion of a Region, usually with a decreasing density in
the areas farther from the urban center. One or more of the sites is
usually in the area of anticipated maximum levels, to monitor for the
attainment and maintenance of NAAQS, while the others serve to monitor
the exposure in neighborhoods (residential, downtown, commercial, etc.).
The primary goals of S02 monitoring are all relatively well-served by
such a population-oriented network with a typical site-to-site distance
of at least 2 to 4 kilometers. Typically regional 862 networks consist
of a mixture of continuous instrumentation and bubbler sites, and this
is considered appropriate; an acceptable distribution between the two
types is presented in Table II-3. The use of continuous instrumentation
at more sites than indicated in Table II-3 at all sites, is acceptable
(if somewhat expensive); the use of less continuous and more bubbler sites
is not recommended.
Table II-3. DISTRIBUTION OF CONTINUOUS AND
BUBBLER S02 INSTRUMENTATION
Number of S02 Sensors
Total
1
2
3
4
5
6
10
15
20
25
30
35
40
Continuous
0
0
0
1
1
2
3
5
7
10
13
15
17
Bubbler
1
2
3
3
4
4
7
10
13
15
17
20
23
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This overall assessment, of adequacy of S0? networks is based on the
use of emission inventories to develop S02 emission density patterns
with special consideration given to any major industrial process S02 .
source that might cause significant deviations from a relatively smooth
geographic distribution. In those few Regions with no significant S0?
emissions, relatively less dense networks are adequate.
It there are significant industrial sources, or concentrations of smaller
sources, the network should include additional sites to monitor exposures
in any adjacent residential areas. In this context, significant S02
source is intended to refer to such as refineries, smelters, etc., that
have numerous emission points. Major fuel-burning sources, such as power
plants, which have only a very few elevated emission points, should be
considered in the context of the discussions in Supplement B. A third
situation requiring a significant deviation in the density of the network
is that of unusual topography. Major topographic features, such as hills
and valleys, that destroy the smooth uniformity of air quality patterns,
require additional monitoring to define the discontinuity.
In general, current SCL state monitoring efforts are typically adequate
in comparison to the monitoring efforts directed at other pollutants. The
primary need in the near future will be for some reallocation of monitors
in the form of increased density in designated Air Quality Maintenance
Areas for S02 and around major isolated point sources, from the urban
core area or the CBD.
2.1.3.2 Suspended Particulate Matter - The general pattern of particu-
late networks is usually similar to that for S0?, in many cases consist-
ing of the same sites. This is reasonable, since the two pollutants both
have a widespread multitude of small sources, frequently the same sources.
There are, however, differences in the nature of the two pollutants that
may lead to some differences in the network configuration. Since entrain-
ment from the ground and other "fugitive dust" sources can be important
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for particulates, the issues of actual siting become of greater importance
than with S0?. In the past, a suspended particulate network that was
largely coincident with the S02 configuration was generally considered
adequate. However, as the traditionally important particulate sources
(industrial processes and fuel combustion, small coal-fired boilers) have
been eliminated or controlled, other types of sources (re-entrained urban
dust, rural fugitive emissions) have become of jajor concern. Hence, a
reallocation of monitors to neighborhood and rural sites, as opposed to indus-
trial peak sites, will be needed to understand these new problems and
develop appropriate control tactics.
2.1.3.3 Carbon Monoxide - In contrast to the case with S0? and particu-
lates, the general configuration of a typical CO monitoring network is
neither well-defined nor adequate. In most cases, CO monitoring is con-
ducted at only three or four sites in an urban AQCR. Because the measured
CO levels are very sensitive to the exact placement of the inlet probe,
the possibility of biased information resulting from this scarcity of
sites is greatly increased.
Designing a CO monitoring network is, thus, quite complicated in com-
parison to other pollutants. This is because of the nature of the NAAQS
for CO, and the differing circumstances in which they are typically vio-
lated. As there is no long-term (annual or seasonal) standard for CO,
the objective of determining trends and patterns is of a good bit less
importance, and the objective of monitoring attainment and maintenance of
NAAQS is more complicated. The issue is further complicated by the dif-
fering circumstances under which the 1-hour and 8-hour standard are typi-
cally violated, which is determined by the interaction of the strong
daily cycle in CO source strength with the seasonal and daily cycles of
atmospheric mixing potential. The 1-hour NAAQS for CO is typically vio-
lated under circumstances of maximum traffic during the morning rush hour,
often on mornings when a nocturnal radiation inversion has persisted
until the time of the rush hours. Because they depend on having heavy
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traffic for a short period, the peak 1-hour levels typically occur near
points of major traffic volumes. In contrast, the highest 8-hour CO levels
tend to occur in the evening and overnight, and may well occur quite apart
from short-term traffic peaks. This is due primariJy to differential cooling,
down slope drainage and a general reduction in mixing height, commonly occuring
in the evenings and early morning.
It is recommended that the overall CO network configuration should involve
sites of four types which are discussed in detail and prioritized in Supplement
These types are:
• Street Canyon
- Peak
- Average
• Neighborhood
- Peak
- Average
• Corridor
• Background
As discussed in Supplement A, there is generally little likelihood of
totally defining an area's CO air quality patterns with a monitoring net-
work, because the variation in CO levels is so dramatic over such short
distances that the number of monitoring sites required would be totally
prohibitive. Rather, it is considered appropriate to monitor a few care-
fully selected neighborhood and street canyon sites. These should be
selected to typify population exposures under a variety of conditions, so
that one can develop from these a relationship adequate to project the
impact in other similar areas.
2.1.3.4 Photochemical Oxidants/Ozone - The typical configuration used
for oxidant or ozone monitoring has been too often only one site in the
urban center of an AQCR, and frequently the precursor pollutants are mon-
itored at the same site. Because oxidant, as a secondary pollutant, is
not closely related to any geographic source pattern, oxidant levels have
been presumed to be relatively uniform over large areas, and one downtown
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sampling site was not considered too grossly inadequate. This is not neces-
necessarily the wisest practice, however, due to the scavenging effect of
freshly generated NO from mobile sources. Figure II-3 presents the typical
diurnal afctern experienced at such a combined site. The maximum oxidant
levels are not coincident in time with the peak levels of the precursors
and hence are not likely to be coincident in space either. This leads to
the recommendation that peak sites be located 15 to 25 km from the center
of the city in at least two general directions. These two general areas
should be selected based on wind directions during the ozone season. This
season varies, according to local climatology, from May to September in the
North to April to October in the South. Generally, ozone levels above the
NAAQS are not found when daytime ambient temperatures are below 15°C (60°F).
Consideration may well be given to reduced operation of isolated 03 monitors
during the winter months.
In addition to these peak sites, several neighborhood sites may be necessary
for monitoring population exposures in residential, commercial, and downtown
areas, depending on the population and size of the Region. For purposes of
determining possible transport of ozone into the region, it may be necessary
to have sites in remote areas upwind.
2.1.3.5 Nitrogen Dioxide - Nitrogen dioxide has a dual role in air pollu-
tion, so that two different sets of network needs must be considered. There
is an NAAQS for N02, so that peak and neighborhood population exposure must
be monitored. Because of the lag time indicated in Figure II-3, the peak
N02 exposure will not necessarily be at major traffic points of high NO
emissions. However, the timing of the peak can vary significantly through
the year (Figure II-4), so that it does not provide a very rigorous
guide for placing sites. In general, in areas where levels exceed the
standards, a population-oriented network involving both bubbler and con-
tinuous monitoring should be done in peak areas, while the intermittent
monitoring should be at neighborhood and background sites. The peak sites
should be located similar to the peak ozone sites, except that they should
be only 10 to 15 km from the center city.
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8
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0.10
0.05 -
0.10
0.05 -^
0.10
JANUARY N0
-T-|--T -i -1 ir r
1 ' ' ' ' I I
FEBRUARY
0 I i i i i i I i i i i i I i i i i i I i i i I I 1 0 !__!—LJ—!_!_!_!
i i i t t i i i i i
I I I I I I I I I I ' I ! ^ I I I I I -J J 1_1
6pm. 12
NOVEMBER NO
' i i i i i i i I L_t_i i ' i i i i ' i i '
12 60 m. 12 6pm 12
DECEMBER
12 60 m
60. m. 12 6p.m. 12
HOUR OF DAY. EST
Jiil—i I. i i—i i i. I i i i i i I i i i i i
12 6o.m. 12 6p.m. (2
HOUR OF DAY, EST
Figure II-4. Seasonal differences in NO and N02 peaks
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2.1.3.6 Nonmethane Hydrocarbons and Nitric Oxide - The existing monitoring
of nonmethane hydrocarbon and nitric oxide is typically a very limited
effort with one or a few continuous sites in an area. Since there are no
NAAQS, population-oriented monitoring is not necessary and in most areas
is not conducted.
However, data on both NO and nonmethane hydrocarbons are required along
with N02 and oxidant data to provide research and planning information with
respect to photochemical oxidant reduction. Single sites at the urban
center are clearly not adequate for this purpose, as they do not permit any
resolution of spatial distribution and transport-reaction time questions.
It is recommended (although not required) that hydrocarbon and paired NO
X
sensors be located in the CBD of the urban core area when reliable instru-
ments for measuring non-methane hydrocarbons become available.
2.1.3.7 Meteorological Sensors - In addition to data on pollutant concen-
trations, it is necessary to have available some source of meteorological
data for use in dispersion modeling and other data analysis efforts utiliz-
ing the monitoring network data. The data should include wind speed, wind
direction, and vertical stability information, although most networks
include only wind speed and direction, since vertical temperature param-
eters are difficult to monitor in urban areas.
Wind data may often be adequately supplied by the National Weather Service
or by commercial consultants. In other cases, however, the National
Weather Service airport site may be too remote, or the data otherwise less
than adequate, and wind speed and direction sensors should be included in
the air quality monitoring network. Such sensors, if included, should be
placed at sites where several continuous instruments are housed together,
in order to obtain the greatest use of the data for modeling and research
purposes. An adequate number of meteorological sensors would probably be
on the order of one-half or less of the number of such stations.
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Information on vertical stability can usually be adequately obtained in-
directly by utilizing inferred relationships between wind conditions, time
of day, insolation and vertical stability classes. Observations of temper-
ature at several heights near the surface are very useful to infer stability
for short-term modeling and air quality forecasting, but extensive measure-
ment of vertical parameters is usually only done on a research basis.
2.1.3.8 Combined Sites - As has been noted above, it has been common prac-
tice to consider the configuration of an entire network covering all pol-
lutants, as a whole rather than on a strict pollutant-by-pollutant basis.
This is, of course, done as a matter of economy, both of cost and manpower,
it generally being more economical to have as many sensors collected at
one site as possible.
It is considered appropriate to combine instruments to a certain extent.
However, it is not appropriate to routinely house all instruments for all
pollutants together as has often been common practice, except for back-
ground sites.
The peak and neighborhood type sites for total suspended particulate and
SO™ may very reasonably be combined. As was noted, it is specifically
recommended that in the case of research and planning sites, hydrocarbon
and oxides of nitrogen sensors be collected together together into sta-
tions, which may also reasonably include hi-vols and S0£ sensors.
However, as also noted above, the locations of peak levels of the various
pollutants are in most cases not at the same location within the area.
Most prominent example of this is carbon monoxide. Although it is obvi-
ously convenient to have all the continuous sensors together, it is
extremely rare to find a site large enough for a full monitoring station
that is also in an appropriate location for peak CO monitoring and,
indeed, sites suitable for CO monitoring are not necessarily suitable for
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other pollutants, depending on the purpose. Hence it is not prudent to
presume that CO sensors can be located with the others, although if pos-
sible of course it should be done.
2.1.4 Ad d i ti ona1 Quid ance
Other recent and current EPA contract efforts relevant to the issues of
network design, optimization, and evaluation include:
Guidelines for Air Quality Maintenance Planning and Analysis,
Volume 11; "Air Quality Monitoring and Data Analysis"
Subject Matter; This document provides states with
planning information and guidance for the preparation
and implementation of a monitoring system which is
compatible with the goal of air quality maintenance
and the need for the development of Air Quality Main-
tenance Plans.
Status; The guideline document (also identified as
EPA-450/4-74-012 and OAQPS #1.2-030) has been completed
by the GGA Corporation, September 1974.
EPA Project Officer: Alan J. Hoffman, MRB, HDAD, OAQPS.
Collection and Integration of Operational Characteristics of
Existing Pollutant Monitoring Networks
Subject Matter; This study deals with the analysis of
operational data gathered from five superior air and
water monitoring networks to identify the most efficient
and economical methodology by which a monitoring network
can satisfy its responsibilities and optimize the cost-
effectiveness of daily operations. The goal of the pro-
ject is the development of manuals that would furnish
the desired techniques for evaluating operations, and to
provide methodologies by which the efficiency and/or
cost-effectiveness of all operations could be readily
considered along with the effects of alternative actions
where the evaluation indicates that improvement is needed,
while remaining within budgetary constraints and meeting
network objectives.
Status; The project is being carried out by URS Research
Corp. and is expected to be completed by November 1975.
EPA Project Officers: Edward A. Schuck and
Leslie Dunn, MSA, NERC-LV
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2.2 INSTRUMENT SITING AND PROBE EXPOSURE
After the general location of a sampling site is selected, based on con-
sideration of the Region-wide configuration, it is necessary to select a
site for the sensor or station, and then within the confines of that
choice to determine the precise location of the inlet probe in the case
of gaseous pollutants.
2.2.1 Site Selection
The selection of a precise site, once a general area has been
selected, is primarily a question of availability, accessibility, secu-
rity, and the potential effect of surrounding structures. The issues of
accessibility and security are the ongoing concerns of the daily opera-
tion of a network, and there is little additional guidance to be offered.
The issues of ground-level versus rooftop sites might be considered a
site-selection problem, as availability is one of the primary reasons for
seeking rooftop sites; however, the impact of the choice is more in the
nature of a probe placement issue, and it is so considered here.
Sulfur dioxide is considered to be rather well mixed near the ground, at
least at receptors not overly affected by specific point sources. There-
fore, either ground or roof-top sampling is adequate, and the choice can
be made on the basis of site availability. However, care must be taken to
ensure that rooftops are 'clean,' i.e., free from space heating vents,
laboratory hood vents, and the like, that may have S02 emissions. Once above
the effect of reentrainment from the ground, it is generally considered
that TSP is also fairly well mixed for the next few hundred feet above the
ground. Hence rooftop sampling has traditionally been recommended in order
to avoid influence of possible reentrainment effect, and rooftops up to
several stories high have been used, particularly at center city sites. If
the reentrainment is to be considered, however, perhaps as part of the popu-
lation exposure, then a site that permits ground level (2 to 3 meters)
sampling is required. If such a site is not attainable, an alternate
arrangement such as a portable sampler should be considered. This is a
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clear instance where the purpose of the monitoring needs to be very
precisely stated to determine the appropriate siting action.
The obvious case where station siting depends on the purpose of the
monitoring is with CO, where a station may be either a street canyon,
neighborhood, corridor, or background station. In contrast to the case
with S02, the horizontal distribution of CO across an urban area consists
of so many alternating areas of peak and valley levels, one at each
street or major traffic center, that one must consider site locations
for CO primarily in probe placement terms, in scale of plus or minus a
meter or two. Hence a peak station site needs to be essentially adja-
cent to the street in question and needs to permit nose-level sampling,
while a neighborhood site must be located at least 35 meters from the
nearest street. This setback will limit the influence of the nearest street
to about 1 ppm and make the reading more representative of the general
community in which the monitor is located. The strong dependence of carbon
monoxide concentration upon distance from the nearest roadway has been
illustrated in a number of studies. ' Generally it was found that the
concentrations experienced by pedestrians exceeded those measured at a
typical air monitoring site, while concentrations at randomly selected
locations throughout the survey grid were less than those at the site.
More specifically, the data in one study indicated that average concentra-
tions determined by the monitor would be reduced to near the urban back-
ground level by moving the monitor approximately 200 feet farther back
Q
from the street. Figure II-5 indicates how the CO levels at the various
stations in Los Angeles are closely related to the slant distance from
the street, despite presumably different traffic volumes in the various
locales. It is also known that for peak CO sampling within street canyons,
the side of the street which is opposite the side facing the rooftop-level
winds will experience the higher concentrations (see Figure II-6). Hence
in any location with a significantly prevailing wind direction, even the
choice of the side of the street becomes a relevant siting question.
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BACKGROUND
CO CONCENTRATION
PRIMARY RECEPTOR
VORTEX
TRAFFIC
LANE
-W-
Figure II-6. Schematic of cross-street circulation in street canyon'
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2.2.2 Probe Placement
Within the several meters scale involved in a typical monitoring site,
there is general latitude in the precise placement of the inlet probe.
For the gaseous pollutants (excepting CO), this is an issue primarily
involving security from vandalism, the avoidance of any restrictions
to the air flow, such as from the station itself, trees, etc., and any
undue influence from a minor local source, such as a stack located on
the roof of a building where the air inlet is located. These require-
ments are generally taken to indicate a height above the ground of 3
to 15 meters, and either a vertical clearance above the roof of 1 to
2 meters or, in a different configuration, a horizontal clearance
beyond the supporting structure of at least 2 meters.
In the case of particulates, the hi-vol represents a special situation.
Historically, the NA.SN hi-vols have been on rooftops, sometimes 8 to
10 stories high. This avoids reentrained surface dust, and the atten-
dant variability, and in so doing provides a smoother, more reliable
record for trend purposes. However, it can be argued that elevating
the sampler in this way makes the resulting data an inaccurate reflec-
tion of true population exposure. Table II-4 provides, as an example,
a comparison of 5 months' data from the CAMP Station in Philadelphia
and the Franklin Institute site operated by the Philadelphia Department
of Public Health. The CAMP Station hi-vol, at 11 feet, reads consis-
tently higher than the City Station, at the same location, which is at
about 50 feet. It is probably also true, though perhaps less thoroughly
demonstrated, that the distance of the hi-vol from a nearby street is of
importance. Since streets, walkways, and other such areas are a source
of reentrained particulate matter, it is probable that placing a hi-vol
on a one-story roof, for instance, is not the same as placing it in an
open area or on a trailer, even if the height above the ground is the
same.
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The pollutants NMHC, NO, N0£ and 03 are tied together in a precursor -
secondary product relationship and should therefore be considered as
an integrated system in site selection. While hydrocarbons are emitted
in much the same pattern as CO, an elevated site in the CBD is more appro-
priate than a ground level one. This is to limit the influence of any
single street and provide a more representative measurement of the CBD
as a whole. NO and N02 should be monitored at this location to provide
information on ratios of NMHC to NO and N02-
As photochemically produced secondary pollutants, N02 and 03 are con-
sidered to be well mixed vertically and of relatively uniform concen-
tration over a large area. Therefore, either rooftop or ground level
sampling are adequate and the prime concern is the location of a
favorable distance downwind of the CBD to locate the zone of maximum
concentration. Under normal wind speeds, this zone thought to be 10-
15 km for N02 and 15-25 km for oxidants. Special precaution should be
taken not to locate 03 sites within 100 meters of major traffic
arteries or large parking areas due to the scavenging effect of NO
emissions.
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Table II-4. COMPARISON OF HI-VOL DATA AT TWO DIFFERENT
HEIGHTS - FRANKLIN INSTITUTE, PHILADELPHIA
Date
Nov. 1, 1974
Nov. 13, 1974
Nov. 19, 1974
Nov. 25, 1974
Dec. 1, 1974
Dec. 7, 1974
Dec. 13, 1974
Dec. 19, 1974
Dec. 25, 1974
Dec. 31, 1974
Jan. 1, 1975
Jan. 6, 1975
Jan. 8, 1975
Jan. 12, 1975
Jan. 18, 1975
Jan. 24, 1975
Jan. 30, 1975
Feb. 5, 1975
Feb. 23, 1975
Mar. 1, 1975
Mar. 7, 1975
Mar. 13, 1975
Mar. 19, 1975
Mar. 25, 1975
Mar. 31, 1975
Geometric mean
City
199
48
122
69
73
113
174
94
101
54
31
88
107
42
54
153
44
45
64
80
119
84
56
84
46
76
CAMP
264
76
187
116
117
154
237
133
143
82
52
190
136
71
76
228
81
76
138
254
206
122
92
128
94
125
Ratio
1.33
1.58
1.53
1.68
1.60
1.36
1.36
1.41
1.42
1.52
1.68
2.16
1.27
1.69
1.41
1.49
1.84
1.69
2.16
3.18
1.73
1.45
1.64
1.52
2.15
1.64
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t
It is recognized that the effect of height seen in Table 2, and other
similar concerns, indicate that many of the hi-vol networks and sam-
pling sites that have been used in the past are generally not as com-
parable with each other as is the case with other pollutants. Ulti-
mately, the need for a greater degree of homogeneity will likely require
that adjustments be made in the way hi-vols are typically placed. How-
ever, because of the large number of sites involved, and the length of
historical record at many of them, such an adjustment would be an issue
of major concern and significance. Since a large amount of good quanti-
tative information on the topic is not currently available, it is con-
sidered inappropriate to make major recommendations at the present. The
effect of height, etc., can be taken into consideration in interpreting
hi-vol data, and it is recommended that this be consistently done.
Several study programs are underway that will provide much better infor-
mation on these questions in the near future, and the guidance material
will then be revised as appropriate. It is expected that guidance in this
area will be in the form of a supplement to this document, similar to the
CO Supplement, and will be issued in early 1976.
However, the issue of probe placement is the most serious concern in the
case of CO. Even within the scale of a typical monitoring site, CO
levels can vary dramatically. As indicated in Figure II-7, CO levels
can change with vertical height at a rate more than 1/2 ppm per meter.
Figure II-8 illustrates the sizable changes possible with short hori-
zontal changes in the vicinity of a typical peak site location. Thus,
while there is no single "right" position for a CO probe, it is obious
that some major degree of standardization is needed to ensure uniformity.
The currently recommended positions are discussed in Supplement A. These
positions were selected not only to standardize probe and station
locations, but also to provide a reasonable measure of population exposure
in the breathing zone.
A summary of the current recommendations concerning station siting and
probe placement is presented Table II-5.
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40
30
o
UJ
X
20
10
LEEWARD SIDE
OF STREET
WINDWARD SIDE
OF STREET
till ^V
O
10 15
CO,ppm
20
Figure II-7. The vertical distribution of CO concentration on a
street with traffic volume of 1,500 vehicles/hour'7
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2.2.3 Additional Guidance
Other recent and current EPA contract studies relevant to the issues
of site selection and probe placement include:
"Selecting Sites for Carbon Monoxide Monitoring"
Subject Matter; This report presents procedures and
criteria for selecting appropriate locations for CO
monitoring stations which fulfill specific monitoring
objectives. Procedures are given for selecting loca-
tions that will provide CO measurements representative
of downtown street canyon areas, urban neighborhoods,
and larger interurban regions. Specific recommenda-
tions are given for inlet heights, distance from major
and minor roadways and placement re ative to urban
areas. The rationale behind each specific recommenda-
tion is also given.
Status; The first draft report prepared for EPA by
Stanford Research Institute is being reviewed. A
final report is expected by the end of September 1975
EPA Project Officer; Neil J. Berg, Jr., MRB, MDAD, OAQPS
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"Determine Optimum Site Exposure Criteria for TSP Monitoring"
Subject Matter: The purpose of this contract is to develop
specific optimum site exposure criteria for TSP monitoring
which could be applied generally. Criteria will be developed
for a limited number of different tj'pes of sites, each of
which achieves some specific monitoring objective or set of
objectives. This will be accomplished by the following:
(1) conduct a literature search on the nature and purpose
of ambient TSP monitoring; (2) determine a specific set of
objectives to be achieved by ambient TSP monitoring and the
relative importance of each objective; (3) delineate repre-
sentative types of monitoring sites which achieve one or
more of the monitoring objectives; (4) for each representa-
tive type of site, determine optimum exposure criteria which
could be applied uniformly to that type of site; and (5) for
each type of site, determine the relative effects of various
TSP sources both nearby emitters and those further away.
Status; Stanford Research Institute has been chosen to
perform this study.
The expected completion date is March 1, 1976.
EPA Project Officer; Neil J. Berg, Jr., MRB, MDAD, OAQPS.
"Determine Optimum Site Exposure Criteria for SO,, Monitoring"
Subject Matter: This project is similar to the one for TSP
monitoring described above.
Status: The Center for Environment and Man has been chosen
to perform this study. Estimated completion date is February 1, 1976,
EPA Project Officer: Neil J. Berg, Jr., MRB, MDAD, OAQPS.
Monitoring and Data Analysis Division.
"Study of the Feasibility of Determining Optimum Site Exposure
Criteria for 0 . NO,., and Hydrocarbon Monitoring"
x /
Subject Matter: The purpose of this contract is to in-
vestigate the feasibility of determining optimum site
exposure criteria for Ox, N0£ and hydrocarbon monitoring
which could be applied generally. This will be accom-
plished by the following: (1) conduct a literature search
on the nature and purposes of Ox, N0£ and HC monitoring;
(2) determine a specific set of objectives to be achieved
by Ox, N©2 and HC monitoring, and the relative importance
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of each (if there is a lack of data which precludes this
determination of monitoring objectives, fully document
this data void and suggest means to obtain the necessary
information); (3) delineate representative types of moni-
toring sites which achieve one or more of the monitoring
objectives; and (4) prepare a final report summarizing as-
sumptions, findings, and conclusions of this study.
Status; Stanford Research Institute has been chosen to
perform this study. Estimated completion date is December 1,
1975.
EPA Project Officer: Neil J. Berg, Jr., MRB, MDAD, OAQPS
"Development of a Study Plan to Determine the Air Quality Grad-
ients at Air Monitoring Sites"
Subject Matter; The purpose of this contract is to develop
a study plan to define the area for which a point samplers
data may be "representative." The study plan should address
various pollutants, differing monitoring objectives, and
site exposure criteria in determining the three-dimensional
air quality gradients around monitoring sites. The plan
should define limits of "representativeness" as well.
Status; Rockwell International Air Monitoring Center has
been chosen to perform this study. The expected completion
date is December 1, 1975
EPA Project Officer; Alan J. Hoffman, MRB, MDAD, OAQPS
2.3 NETWORK OPERATION
In addition to defining the configuration of the network and actually
siting the monitors, the process of monitoring network design also in-
cludes the selection of appropriate instrumentation and the definition
of various procedures for the operation of the network.
2.3.1 Monitoring Equipment Selection
The selection of monitoring instruments for use in a network is an im-
portant aspect of overall network planning. EPA has established a set
of procedures for establishing whether monitoring methods are reference
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methods or equivalents, and thus acceptable for meeting SIP requirements.
This was published as a regulation in 40 CFR 53 on February 18, 1975.
The burden of proof of whether an analyzer is a reference method or
equivalent falls upon the manufacturer. Many analyzers currently in
use are no longer manufactured per se (that is the specific make and
model). Since the vendor will have no incentive to test these analyzers
for reference method or equivalency, EPA will in most cases make the
necessary tests.
2.3.1.1 Reference Method Determination - For SO- and TSP, the measure-
ment principle specified is a manual method. (Pararosaniline for S0_,
hi-vol for TSP) thus, there is only one reference method for S0? and TSP
since the method consists of a series of mechanical steps or chemical
operations to be performed. For CO, ozone and N0_, only the measurement
principle and calibration procedure has been specified. Any analyzer
utilizing the specified measurement principle and calibration procedure
and which meets the performance specifications in 40 CFR 53 will be
designated as a reference method. Thus, as an example, there could be
as many reference methods for CO as there are different models of
NDIR analyzers.
2.3.1.2 Equivalency Determination - In general, equivalency to a refer-
ence method is determined by passing the tests for demonstrating a
consistent relationship to a reference method and by meeting performance
specifications. If the candidate equivalent method is a manual method
only the consistent relationship need by established. If the method is
an automated method then both the consistent relationship and performance
specification tests must be passed in order to be designated as an
equivalent method.
At the present time, reference methods exist only for S0_ and TSP which
are described in 40 CFR 50. They are the high volume procedure for TSP
and the pararosaniline (sulfamic acid) procedure for SO-. Any other
manual methods for these pollutants are unacceptable.
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For CO and ozone, EPA is awaiting data from manufacturers before designat-
ing any reference methods. For the present time, any instrument utiliz-
ing the NDIR measurement principle for CO and the chemiluminescent prin-
ciple for ozone will be acceptable. It is possible that instruments
utilizing the NDIR principle for CO or the chemiluminescent for 0,. will
be unacceptable. This situation could occur if the manufacturer fails
(or if EPA tests the analyzer and it fails) to pass the performance
specifications tests.
For N0~, no reference measurement principle or methods exists since the
Jacobs-Hochheiser (J-H) technique was rescinded. The chemiluminescent
measurement principle will be proposed very soon to replace the J-H tech-
nique. The triethanolamine guiacol sulfite orifice method (TGS) and the
sodium arsenite orifice (ARS) method will be tested for equivalency as
soon as a reference method is designated.
Unacceptable manual methods should be changed to the reference method
or equivalent witHin 6 months. Unacceptable analyzers (automated methods)
should be changed to a reference method or equivalent as soon as prac-
ticable but no later than 5-years (February 1980).
Automated analyzers not utilizing the reference measurement principle
and calibration procedure and which fail equivalency tests should be
replaced with a reference method as soon as practicable but no later
than 5-years (February 1980).
2.3.2 Operating Procedures
There are at least two types of operational decisions that affect the
design of the network in the sense that they affect the type of data
produced. In the case of intermittent sampling, the frequency of opera-
tion is such a decision, and in the case of continuous monitoring, the
selection of the instrument operation range is also. Note that the many
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other operating procedures associated with the quality assurance aspects
of a monitoring network are not considered here, although they are none-
theless of major importance also.
2.3.2.1 Intermittent Sampling Frequency - The entire point of sampling
intermittently, such as the every-6-days schedule used for hi-vols and
bubblers, is to provide some measure of air quality knowledge at a cost
less than that associated with more frequent sampling. Such a program
necessarily introduces some uncertainty into the statements that can be
made based on the resulting data. However, standard statistical pro-
cedures are available to provide estimates of this uncertainty, and to
indicate how to adjust the sampling frequency to provide an appropriate
degree of uncertainty.
Figure II-9 indicates how the range of uncertainty with respect to the
NAAQS varies with the sampling frequency. At 61 samples per year, an
3
annual mean TSP level of 75 may be 8 |ig/m higher or lower (95 percent
confidence limits); if the sampling frequency is tripled, the uncer-
3
tainty drops to + 3 (ig/m . Thus, with sites having levels near the
standard, greater sampling frequency may be needed to precisely define
compliance, while at sites with levels well above or well below the
standard, less frequent sampling may be adequate. It should also be
noted that the uncertainty increases or decreases linearly with the
value of the standard geometric deviation; the 1.6 used to calculate
Figure II-9 is a typical value.
Table II-6 presents similar information relevant to the 24-hour standards;
specifically the table presents the probability, for each of three sam-
pling frequencies, that at least 2 of the days over the 24-hour standard
will be detected; i.e., that the site will be considered in violation of
the standard. Note that, again, if the site is only marginally in viola-
tion, quite frequent sampling is needed to detect this, while a site a
large number of excursions is almost assured of being so identified.
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YEAR
ual primary standard for '.
etric deviation equals 1.6
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Table II-6. PROBABILITY OF SELECTING TWO OR MORE DAYS WHEN SITE
EXCEEDS STANDARD
Actual number of
excursions
2
4
6
8
10
12
14
16
18
20
22
24
26
Sampling frequency, days/year
61/365
0.03
0.13
0.26
0.40
0.52
0.62
0.71
0.78
0.83
0.87
0.91
0.93
0.95
122/365
0.11
0.41
0.65
0.81
0.90
0.95
0.97
0.98
0.99
0.99
0.99
0.99
0.99
183/365
0.25
0.69
0.89
0.96
0.99
0.99
0.99
0.99
0.99
0.99
0.99
0.99
0.99
2.3.2.2 Instrument Operating Range - Since continuous instruments can
usually be adjusted electronically to operate in various concentration
ranges, the selection of such range is a necessary decision in the pro-
cess of network design. Generally, the decision is simply to utilize
the smallest range that will encompass the maximum expectable levels,
and this is usually adequate. However, in the case where very high
levels (usually SO,,) from a major source are received at a site that
normally experiences low background levels, the use of a single range may
not be possible. If the range is set too low, accurate documentation of
the peaks is lost offscale, while if it is chosen high, there will not be
adequate precision in the data concerning the low levels. There is no
way to resolve this with a single instrument. In such a case, one or the
other orientation (population or source) must be selected as primary, and
the instrument site coded 01 or 02 as appropriate. A good solution would
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be to have a continuous Instrument adjusted to measure the peak levels,
and a bubbler for long term population exposure.
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SECTION III
REFERENCES
1. Code of Federal Regulations. Title 40. Section 51.17.
2. Federal Register. Volume 33, Number 10. January 16, 1968.
3. McCormlck, Robert A. Air Pollution Climatology. Chapter 9 in
Stern A.C., Air Pollution. 2nd Edition. Academic Press. 1968.
4. Lynn, David A. Air Pollution-Threat and Response (in press)
Addison-Wesley. Reading, Mass. 1976.
5. CAMP in Washington, D.C. 1962-1963. Publication Number AP-23.
Department of Health, Education and Welfare. 1966.
6. Kinosian, John R. and Dean Simeroth. The Distribution of Carbon
Monoxide and Oxidant Concentrations in Urban Areas. California
Air Resources Board. 1973.
7. Johnson, W. B. et al. Field Study for Initial Evaluation of
an Urban Diffusion Model for Carbon Monoxide (APRAC-la). Contract
CAPA-3-68 (1-69). Stanford Research Institute. 1971.
8. Ott, Wayne R. An Urban Survey Technique for Measuring the Spatial
Variation of Carbon Monoxide Concentrations in Cities. Depart-
ment of Civil Engineering. Stanford University. 1971.
9. Guidelines for the Interpretation of Air Quality Standards. OAQPS
Guideline Numbers 1.2 - 008. 1974.
III-l
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GUIDELINE SERIES
OAQPS NO. 1.2-005A (Revised)
REVISIONS TO STATE IMPLEMENTATION PLANS -
PROCEDURES FOR APPROVAL/DISAPPROVAL ACTIONS
OCTOBER 1975
US. ENVIRONMENTAL PROTECTION AGENCY
Office of Air Quality Planning and Standards
Research Triangle Park, North Carolina
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TABLE OF CONTENTS
Page
List of Abbreviations iii
T.O INTRODUCTION 1
1,1 Purpose 1
1.2 Overview 3
2.0 SPECIAL ISSUES 6
2.1 Division of Authority 6
2.2 Delegation of Authority to the Regional Administrator
to Sign Proposed Rulemaking Packages 7
2.3 Court Decisions 7
2.3.1 Opportunity for Public Comment 8
2.3.2 Requirements for Approval/Disapproval Action ... 8
3.0 hEDERAL REGISTER PACKAGES 9
ITT Content 9
3.1.1 State Submitted Revisions to SIPs 9
3.1.2 SIP Revisions Originated by the Regional Office. . 10
3.1.3 Preparation of FEDERAL REGISTER Actions 11
3.2 Procedural Problems - When State Submittal is Not
Approvable 13
4.0 CLASSIFICATION OF SIP REVISION 14
5.0 HEADQUARTERS REVIEW AND COORDINATION 18
5.1 Office of the Administrator 18
5.1.1 Office of General Counsel 18
5.1.2 Office of Regional and Intergovernmental Operations 18
5.2 Office of Air and Waste Management ly
5.2.1 Office of Air Quality Planning and Standards ... 19
5.2.2 Office of Transportation and Land Use Policy ... 19
5.3 Office of Enforcement * 20
5.3.1 Office of General Enforcement 20
5.4 Office of Planning and Management 21
5.4.1 Office of Planning and Evaluation 21
5.4.2 Office of Administration 21
5.5 Assistance to Regional Offices by Headquarters Staff
Offices 21
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6.0 PROCESSING OF NORMAL SIP REVISIONS 22 *
6.1 Proposed Rulemaking 22
6.2 Handling Public Comments 24 •
6.3 Final Rulemaking 24 •
6.4 Procedure for Headquarters to Change a Normal Action
to a Special Action Issue , 25 •
7.0 PROCESSING OF SPECIAL ACTION SIP REVISIONS 26
7.1 Proposed Rulemaking 26 _
7.2 Public Advertisement 27 •
7.3 Handling Public Comments 27 •
7.4 Final Rulemaking Action 27
7.5 Non-Concurrence 28 •
FIGURE 1 Organization Chart for Headquarters Review and «
Coordination iv I
FIGURE 2 FEDERAL REGISTER Components - hinal Rulemaking .... 12
FIGURE 3 Procedures for Normal SIP Revisions ..... 2y •
FIGURE 4 Procedures for Special Action SIP Revisions 30
11
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T OF ABEREV IATI UNS
A Administrator
OGU Office of General Counsel
AQNRU Air Quality, Noise, and Radiation Division
ORIO Office of Regional and Intergovernmental Operations
OAWM Office ot Air and Waste Management
CTLUP Office of Transportation and Land Use Policy
OAQPS Office of Air quality Planning and Standards
CPDD Control Programs Development Division
OE Office of Enforcement
OGE Office of General Enforcement
DSSE Division of Stationary Source Enforcement
MSED Mobile Source Enforcement Division
0PM Office of Planning and Management
OPE Office of Planning and Evaluation
DSR Division of Standards and Regulations
OA Office of Administration
MOD Management and Organization Division
PIRU Public Information Reference Unit
AA Assistant Administrator
RO Regional Office
RA Regional Administrator
AQMP Air Quality Maintenance Plan
TCP Transportation Control Plan
tii
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REVISIONS TO STATE IMPLEMENTATION PLANS -
I PROCEDURES FOR APPROVAL/DISAPPROVAL ACTIONS
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1.0 INTRODUCTION
i.1 Purpose
The Administrator has ordered that the Regional Offices be
I delegated maximum responsibility allowed under the law to process
rulemaking actions. Consequently, EPA headquarters review
I responsibilities will be reduced to be consistent with the
• increase in the Regional Office's responsibility in processing
SIP rulemaking actions. However, despite increased Regional
• Office responsibility, EPA headquarters will retain the con-
currence role in "special action" cases.
| This document supersedes Interim Guideline OAQPS 1.2-005A
« (Revised) entitled Revisions to State Implementation Plans -
Procedures for Approval Disapproval Actions (April 1975) to
• implement this policy, which was announced in a July 22, 1975,
OAWM/OE memorandum to the Regional Administrators. This
| Guideline also supersedes OE Guideline S-5 entitled Procedures
• for Review and Approval of Compliance Schedules Pursuant to
S 51.6 to the extent that 1.2-005A and j>-5 conflict.
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Major changes in this Guideline which implement the new •
policy are as follows: •
a. The promulgation of SIP revisions will be viewed as falling
into two categories with regard to the nature and extent I
of appropriate headquarters review of Regional Office actions.
These categories are called "normal" and "special action" 8
SIP revisions. EPA headquarters staff elements will not •
review normal SIP revisions, but will be involved in policy
review of special action SIP revisions. Lven so, the review •
of special actions is revised from that required in the
Interim Guidelines (April 1975) and will be streamlined to |
accomplish the aims previously described. Normal and special «
action SIP Revisions are discussed in detail in Section 4.
b. The current distinction between "State-initiated" and "EPA- •
initiated" SIP revisions will be eliminated. Pursuant to
EPA Order 1265.1A, September 15, 1975, the Regional Adminis- |
trator may sign proposed rulemaking packages which originate «
within EPA and are proposed as changes to an SIP. ™
c. The Office of Regional and Intergovernmental Operations (ORIO) •
will coordinate proposed and final rulemaking packages for
special action SIP revisions. |
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.2 Overview
These procedures shall apply tc all cJP-^e1?ted actions that.
_ involve a change or modification in the approval of State Imple-
™ mentation Plans (compliance schedules, control strategy, emergency
• pn-Knde, resources, etc.). The processing and evaluation of
such actions will be handled in accordance with these guidelines.
• The Regional Offices are responsible for direct interface with
the State in matters involving the development and submittal of
li SIP revisions. They are responsible for seeing that all material
• germane to the SIP action or matter at hand has been received
from the States and is circulated as needed for review, evaluation,
• recommendations and action. The ORIO in Washington will coordinate
processing actions which require policy review from OE, OAWM,
I OPK, or OGC.
• Procedures for revisions to SIPs may be further divided into
(1) state-initiated, (2) Regional Office-initiated, and (3) head-
• quarters-Initiated. This guideline does not cover headquarters-
initiated SIP revisions.
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Thus-, the procedures involved in processing bIP revisions
-e shown in Figures 3 and 4 and summarized as follows: —
, P.O. receives state submittal, performs general review, or •
develops its own revision and prepares proposed rulemaking •
package. This action is signed by the Regional Administrator
and summarizes the content of the State submission or EPA I
proposal which EPA is considering as a revision to the bIP
and invites public comment generally within 30 days as •
explained in Section 6. The memorandum transmitting a "normal" •
proposed rulemaking package shall state the Regional Adminis-
trator's determination that the rulemaking warrants normal I
action and explain why. Copies of this determination will
be provided to appropriate staff offices; these offices may •
recommend that the appropriate Assistant Administrator consult •
with the Regional Administrator on the need for special
action on the rulemaking. •
b. When Rulemaking is Classified as Normal Action:
(1) Regional Office forwards the proposal to the Federal |
Register through MOD with copies of the prop-sal and M
State submittal to PIRU, CPDD, DSR, and other appropriate
headquarters offices (DSSE, OTLUP, MSED) as appropriate. I
lii) Regional Office evaluates plan revision and public
comments, and prepares final rulemaking package. |
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(iii; Regional Office forwards final rulernaking package (action
• rero, regulation portion, evaluation report of state
submitta!, or technical support for EPA initiated protions)
• thru f'OD to AX fnr the AdrMni st,r?tor ' s signature with
• copies to PIRU, CPDD, DSP,, and to other appropriate offices.
•;iv) No headauarters staff concurrence is necessary for proposal
• or final rulemaking.
c. When Rulemaking is Classified as Special Action:
| (i) Regional Office forwards the proposal to ORIO and forwards
• copies of the proposal and State submittal to PIRU, CPDD,
DSR, OGC, and other appropriate offices.
I (ii) Headquarters staff elements have 14 days to non-concur.
ORIO will assume concurrence if it receives no non-
11 concurrence. ORIU will coordinate non-concurrences as
_ described in Section 7.5 - Non-Concurrences (p-28).
™ (iii) Regional Office evaluates plan revisions and public comments
• and prepares final rulemaking package.
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(ivj Regional Office forwards the final rulemaking package to
ORIO with copies to PIRU, CPDD, DSR, OGC, and other
appropriate offices.
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Headquarters has 14 days to non-concur. ORIO will coor-
dinate non-concurrences as described in Section 7.5 8
Non-Concurrenee (p-28).
d. For Regional Office originated revisions, the technical support |
rationale will be developed prior to the proposed rulemaking m
and will be included in the proposed rulemakinp package. Sub- ™
sequently, the procedures in "b" and "c" above apply. B
2.0 SPECIAL ISSUES
2.1 Division of Authority I
A division of authority regarding policy-making must be
established to resolve non-concurrence during intra-agency review •
when the parties involved are unable to reach agreement. This •
division is necessary to provide an orderly procedure for presenting
such issues to the Administrator and at the same time provide each I
organization the opportunity to be heard. The location of basic
authority on SIP decisions is as follows: B
Primary Responsibility for: uff 1 ce •
Matters of national policy and precedent OAU'M
witn respect to air program issues _
Matters of national policy and precedent OE •
with respect to enforcement issues
Legal/procedural questions OGC 8
Regulatory/non-regulatory questions, where Regional •
policy and precedent has been established and Offices |
local policy issues are predominant.
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In instance' where differences carnot be resclvec', the
Regional Of f i rp will preoare the p^rk^rn w' + h tho nnn-rpnrnrrpnrp
memorandum tabbed and transmit the package to the Administrator
I through ORIO.
r . 2 Delegation of Authority to the Regional Administrator to
• Sign Proposed Rulemaking Packages
• On May 30, 1974 (39 FR 18805) the Administrator delegated
authority to the Regional Administrator and Assistant Adminis-
I trators to sign proposed rulemaking packages involving State -
submitted SIPs. This authority was limited to proposed rule-
• making packages in which the State proposal is presented for
• public comment (generally a 30 day period), and did not include
authority to sign proposals which EPA initiates. An order has
• been issued which delegates authority to the Regional Adminis-
trators and Assistant Administrators to sign EPA-initieted
• proposed rulemaking for SIPs.
M 2.3 Court Decisions
A court decision requires that EPA provide for public comment
I prior to approval /disapproval actions on SIP actions submitted
by States, and that an official action be taken in the Federal
Register regarding all correctly submitted State submissions,
even if the submission is unapprovable or contains major deficiences,
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,".3.1 Cppf.rtui':1ty for Public Comment - In response to the court
Decisions, EPA will provide an opportunity for public review
:nd comment on submissions by States of changes and additions to
the SIP. This opportunity tor public review and comment shall I
be provided through publication of a notice of proposed rule-
making in the FEDERAL REGISTER. SIP revisions originated by a |
Regional Office usually require a public hearing. For purposes •
of this guideline, comments received at a public hearing should ™
le treated the same as other public comments, except that it is fl
iot necessary to forward a copy of the complete hearing record
:o the Public Information Reference Unit. |
z.3.2 Requirements for Approval/Pisapproval Actions - EPA has _
Yequently been delinquent in taking actions on State SIP submittals •
v/hich include unapprovable portions. As pointed out in NRDC v. •
EPA (5 ERC 1879, 1st Cir. 1973), EPA must act to make clear which
portions of a submitted plan are approvable and which are not. •
Thus, for every State submittal which is transmitted in accordance
with EPA's procedural requirements, EPA must act expeditiously to B
disapprove those portions of the submission which are deficient, •
or persuade the State to withdraw such portions.
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fe of the final rulemaking package that must be prepared by the
Regional Office. The action memo, preamble and regulatory
I section, and rationale for approval/disapproval are prepared by
_ the Regional Office. The action memorandum should include (a)
• the date the proposal was published in the FEDERAL REGISTER, (b)
• the normal versus special action determination and (c) the initiator
ti.e., a State or EPA). Section 7 discusses the preparation of the
I final rulemaking package.
3.1.2 SIP Revisions Originated By the Regional Office - The
I proposed rulemaking for Regional Office originated SIP revisions
• includes the same components as the proposed rulemaking package
for a State submitted revision, i.e., cover memorandum, proposed
• rulemaking section, and attachments. However, this action pro-
poses regulations and/or procedures which EPA desires to prp-
IT -"'•' :
mulgate, ratherJthan summarizing a SIP revision proposed by the
• State for which EPA is soliciting comments, as in Section 3.1.1.
Consequently, the proposed rulemaking includes definite procedures
• and/or regulations recommended by EPA. It also usually notifies the
public of EPA's intention to hold public hearings en such proposal.
| The attachments will consist of EPA's technical support document
M for this action and other appropriate technical documentation.
This proposed package may be signed by the Regional Administrator
• pursuant to EPA Order 1265.1A of September 15, 1975.
The final rulemaking package contains the same components as
H •Hie ns^Uanci r»"^ "•"""' fr\r- nyr.r-t 11 r-sf T on rf Ctatp e; uhpii 1"fpfl ^TP
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3.0 FEDERAL REGISTER PACKAGES
3.1 Content I
"• •* ' '"'t.J^^l.-'I.J-!'"' ----- - j ^" T p ~' — t- p r- rt < n r- r- r /- ~- ~ _
U. !. 1 ^ 00 ufc OUUIi. I t ucu l.i v i j i 0/13 uu uirS " (F16S6 rt.ULhr.i- r\i-Ui wi I i_f, •
actions have two stages. They consist of the proposed rulemaking
stage, in which public corrment is solicited on the proposed action, I
and the final rulemaking stage in which the action is promulgated.
The proposed rulemaking package normally includes three components, |
the cover memorandum, notice of proposed rulemaking, and attachments. ^
The proposed rulemaking section states that certain specific mater- ™
ial has been received from a State as a proposed amendment to the I
SIP, summarizes the content of this proposal and explains that
this proposal is available for public comment. The proposed rule- |
making should not contain a statement as to whether EPA thinks it _ -';"
is approvable; without such a statement, it is easier for EPA to *
"go either way" during the final rulemaking without worrying • _"
about reproposal. The cover memorandum should indicate (a) whether
the revision is State-initiated or EPA-initiated, (b) whether it |
is a proposal or the final package, and (c) the Regional Adminis- _
trator's classification of the SIP revision, i.e., normal or •
special action, with an appropriate rationale for this classifica- •
tion. The attachments include a copy of the State submittal,
summary of the State public hearings, and any other appropriate I
technical documentation. -
The final rulemaking package may contain as many as four •
components. Figure 2 lists in sequence the possible components
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•
•
rpvisions. The nrpamble includes a discussion of commpntc; yoren'wnH
at the public hearinq held by EPA and comments received during the
public comment period. Appropriate technical support information
• is included in the package.
3.1.3 Preparation of FEDERAL REGISTER Actions - it should be
• emphasized that many approval /disapproval actions result in
• lawsuits. Thus, it is necessary not only to explain EPA's
actions fully in the FEDERAL REGISTER preamble, but also to
• prepare a detailed "Rationale for Approval /Disapproval" of the
State's submission showing EPA's analysis of how the submission
• meets all of the substantive and procedural requirements for
• approval. The Rationale may appear in two forms. It could
appear in the form of an evaluation report where EPA presents
I a detailed review of the State submittals with regard to
applicable portions of the 40 CFR 51 regulations. It could
I appear in the form of a technical support document with
• supportive calculation where EPA developed regulations are
being promulgated, or where certain calculations are required
I in evaluation of a State submission.
A copy of the FEDERAL REGISTER Handbook on Document Drafting,
| January 1975, should be obtained by all personnel involved in the
• preparation of FEDERAL REGISTER notices. This may be obtained
• through the Office of the l-EDERAL REGISTER, National Archives and
• Records Service, Washington, D.C. 20408 (202-523-5266). Two
particularly helpful portions of the Handbook are page 14, where
| preparation of preambles for final rulemaking is discussed, and
page 30, where preparation of proposed rnlernakina oackagps is discussed.
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Fiaure ?. FEDERAL REGISTER Package Components - Final Rulemaking'
RATIONAL hOR APPROVAL/DISAPPROVAL
(2 Copies)
REGULATORY PORTION
(Includes Preamble & Regulatory
Section - Original and 8 copies)
ACTION MEMO
From R.A. to the Administrator
(Through ORIO for special actions,
through MOD tor normal actions -
Original and 1 Copy)
*
a.
Reviewing Offices receive one copy of the Action Memorandum,
Regulatory Portion and Rationale. MOD (Federal Register
Officer) receives the listed number of copies for processing
through to the Administrator.
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3 • 2 ProcejuraJ Problems - _:_-'hen _St ate Subnrittal Is Not_Approvable
• If the State submitial contains major deficiencies, the
Regional Office will attempt to negotiate with the State to correct
I these deficiencies. I^ajor deficiencies include procedural def'i-
• ;•' r^iies in the submission ot the revision (e.g., improper public
rearing was held) or situations where the adoption of the revision
I by the State will result in a deficiency in the bIP (e.g., air
quality standards will be violated).
| In such cases, the Regional Offices shall notify the State
• by letter of such deficiencies as expeditiously as possible after
receipt of plans. This notification shall explain why the sub-
I mission is unapprovable and what, if any, corrective action may be
necessary. It may be appropriate to recorrmend that the State
I withdraw all or part of a submission. If the negotiations are
_ successful and the major deficiencies are corrected, the Regional
* Office shall proceed with the rulemaking action. If the negotiations
I are unsuccessful (the State will not revise or withdraw the sub-
mission), the deficiencies must be disapproved under Part 52 in
| the final rulemaking package, and corrective regulations proposed
_ if necessary. Normally if a State submission is disapproved, the
* present plan remains in effect. However, if the revision has been
• submitted to correct SIP inadequacies and is disapproved, corrective
regulations will be necessary.
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4.0 CLASSIFICATION OF SIP REVISION •
As discussed previously, all SIP revisions will fall into •
one of two categories with regard to the nature and extent of
appropriate headquarters review of Regional Office actions. J
These categories will be called "normal" and "special action"
SIP revisions. For normal SIP revisions, headquarters may com- •
ment but will have no concurrence role. For special action •
SIP revisions, headquarters will have concurrence/non-concurrence
responsibility at the proposal and final rulemaking stage. I
It is anticipated that the majority of SIP revisions will
be treated as normal. The special action category shall be I
reserved for revisions which would have national policy or multi- •
regional implications. National policy implications are inherent
in revisions which address unresolved policy issues, which might I
compromise on-going litigation, or which raise new conceptual
issues. For example, at the present time, national policy implica- •
tions are inherent in any revision addressing issues such as •
increased stack height, intermittent controls, fugitive dust
controls, oil to coal conversions, and approval of Sttte plans •
to prevent significant deterioration. Eventually, however, these
issues will be resolved. After resolution through promulgation |
of regulations in 40 CFR Part 51, or through other appropriate •
mechanisms, and after sufficient experience with interpretation/
implementation ot the promulgated regulations, the great majority I
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of revisions dealing with these subjects will be considered as
• normal. After that time, special actions would be required only
if the revision involved a departure from the generally agreed
• upon policy.
• The magnitude of a SIP revision, and the environmental,
social, or economic impact of that revision, are generally not
I relevant in determining whether a revision needs special action,
although special attention should be given by the Regional Office
| to revisions which do have major environmental, social, or
•j economic impacts to insure that national policy issues are not
involved. To automatically require headquarters concurrence
I on major SIP revisions solely due to their magnitude (such as
Air Quality Maintenance Plans and revisions to SIPs wm'ch are
| "substantially inadequate" for attainment) would result in dup-
_ lication ot Regional Office efforts, and an appropriate Headquarters
review could not be accomplished in the 14 day time period per-
• mitted by the new procedures. For example, AQMPs and TCPs may
contain major environmental, social, and economic impact. How-
| ever, regulations and guidance for development and implementation
— of these plans will be circulated to the Regional Offices from
" headquarters. Comments and suggestions of the Regional Offices
• will have been considered and appropriate revisions made to
these regulations and guidelines. Thus, comprehensive policy
I guidance for review and promulgation of AQMPs and TCPs as revisions
to SIPs will be available, and these revisions will therefore
• usually be classified as normal after adequate experience has been
• gained with implementation of the regulations and guidelines.
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The impact on other EPA Regions will not be considered to I
oe relevant in determining whether a revision needs headquarters
review so long as all potential inter-regional conflicts can be I
resolved by the Regional Offices concerned. The initiating •
Regional Office will be expected to coordinate with other appro-
priate Regions where national policy issues do not exist (as, for I
example, where inter-regional boundary problems exist, or where
several Regions are developing individual regulations for similar |
sources under a generally understood national policy). However, •
the initiating Regional Office must explain the resolution of
inter-regional issues in the Action Memorandum. The threat of I
litigation would not automatically require special action, although
in some cases legal issues could have national policy implications. |
The Regional Counsel is expected to assess whether the threat of _
litigation is such that special action on the SIP revision is •
required, and is expected to consult with the OGC staff when doubt •
exists.
Thus, criteria for classification of normal and special action |
SIP revisions may be summarized as follows:
a. Normal action - Issues which do not have national or multi- •
regional implications, and for which policy has been established. •
For these purposes, policy has been established when the Regional
Offices have received guidance from headquarters in the form of I
regulations and guidelines upon which (1) the R.O.s and other
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appropriate offices have been extended an opportunity to review
such material, (2) the material has been revised to reflect comments
received from the review, and (3) these regulations and guidelines
I have been approved by appropriate EPA offices as representing
agency policy. Some examples of normal issues are:
• (';) Non-regulatory change to a SIP
• (ii) Change in emission standards for new sources to meet
NSPS or NESHAPS
I (iii) Revision to State-specified sampling or stack testing
methods.
• (iv) Change in control strategy of SIP to replace the example
• region approach.
(v) Legal authority to implement EPA regulations (e.g., ISR,
I NSD).
b. Special action - Issues which have national or multi-regional
I implications and for which policy has not been established.
M Regional Offices may exercise discretion in classifying an
SIP revision for special action to get headquarters policy review,
I even though a certain revision might usually be classified as
normal. Some examples of special action issues at this time
| (August 1975) are:
_ (i) Revisions involving stack height
* (ii) Revisions involving intermittent controls
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(iii) Approval of State plans tc prevent significant deter-
ioration •
(iv) Control of fugitive dust
(v) Air Quality Maintenance Plans which contain contro- £
versial land use provisions.
(vi) Transportation Control Plans which contain controversial •
provisions which have a major impact. •
5.0 HEADQUARTERS REVIEW AND COORDINATION
Several groups within EPA review and/or coordinate SIP actions. I
Figure 1 (page iv) presents a skeleton organization chart of these
groups. The function of each group in this regard is summarized below. •
5.1 Office of the Administrator •
5.1.1 Office of General Counsel (OGC) - The Air Quality, Noise,
and Radiation Division (AQNRD) of OGC provides legal advice and I
assistance on all Clean Air Act matters. The R.O. shall send
AQNRD copies of proposed and final rulemaking packages which are I
processed as special action issues. AQNRD will recommend appro- •
priate non-concurrence actions to OGC when warrented.
5.1.2 Office of Regional and Intergovernmental Operations (ORIO) - •
ORIO is a staff office of the Administrator which will coordinate
the processing of proposed and final rulemaking packages for special |
action issues. The R.O.s shall send ORIO appropriate copies of «
the proposed and final rulemaking packages for all special action
issues. ORIO's role is to coordinate the review process, and does I
not include review responsibility.
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uf'Hce of /;'i r ond Waste Management (
I b •? •' Office of PIr Quality PI anting and Standards (OAOPS) -
Research Triangle Park, North Carolina - The Control Programs
| ueve'ioprnent Division (iruu) of uAQFS indinLaini on up-to-ciate JIT
_ file. CPDD and other elements of OAQPS provides technical support
™ and assistance to the Regional Offices on the development, evaluation,
• and promulgation of state implementation plans, including revisions
thereto for the attainment and maintenance of air quality, and
| for the prevention of significant deterioration. The R.O.s shall
send CPDD copies of all proposed and final packages involving SlPs.
• For special action issues CPDD will recommend appropriate non-
• concurrence action to OAWM when warrented.
5.2.2 Office of Transportation and Land Use Policy (OTLUP) -
I Washington. D.C. - OTLUP is a staff office of OAWM which provides
technical support and assistance to the Regional Offices in the
• development, evaluation, and promulgation of transportation and
• land use related SIP actions. The R.O.s shall send OTLUP copies
of proposed and final rulemaking packages involving SIP revisions
I which include transportation and land use elements. For special
action rulemaking involving these issues OTLUP will recommend
I appropriate non-concurrence action to OAWM when warranted.
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:- • 3 0/tvce of tnforcenent (Of.) I
: • • 3 • 1 Of _D ,ce_of General Enforcement I OGE) - Washington, D.C. -
a. The Division of Stationary Source Enforcement (DSSE) of OGE •
provides technical support and assistance tc the Regional •
Offices for the development, evaluation and promulgation of
compliance schedules which are consistent with the previously I
approved control strategy. DSSE also provides support on
the enforcement aspects of SIP revisions involving regulations •
for the control of stationary sources. The R.O.s shall send •
DSSE copies of all compliance schedule approval /disapproval
actions. DSSE shall also receive copies of proposed and I
final rulemaking packages which include regulations for the
control of stationary sources. For special action issues, |
DSSE will recommend appropriate non-concurrence action to OE •
when warranted.
b. The Mobile Source Enforcement Division (MSED) of OGE provides I
technical support with regard to enforcement of regulations
to control emissions from mobile sources. The R.O.s shall |
send MSED copies of proposed and final rulemaking packages «
involving transportation control plans and other regulations
affecting mobile sources. For special action issues, MSED •
will recommend appropriate non-concurrence action to OE when
warranted.
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5 • ^ Offl cer of ^ 1 anning_an_d_ Man argent (OP
5 • 4 • "! Office of £la mruiq_ and Evaluation (OPE) - Washington, D.C. ^
I The Division ff Standard,- am! Peculations (CSR) of OPE conducts
• evaluations of proposed regulations pursuant to its responsibility
for procedural management and substantive evaluation of the develop-
• rental process for agency standards, regulations and guidelines.
The R.O.s shall send DSR copies o* all proposed and final rulemaking
| packages. For special action issues, DSR will recorrmend appropriate
_ non-concurrence action to 0PM when warranted.
5.4.2 Office of Administration (OA) - Washington, D.C. - The
I Management and Organization Division (MOD) of OA contains two
components which coordinate SIP actions as follows:
| a. The Public Information Reference Unit (PIRU) is located in the
_ Library Systems Branch of MOD, and serves as a focal point
™ where a record of EPA actions is available to the public. Copies
• of all proposed and final rulemaking actions, along with related
attachments shall be forwarded to PIRU.
I b. The FEDERAL REGISTER Officer is located in the Administrative
_ Management Branch of MOD and serves as a liaison between EPA
• and the Office of the FEDERAL REGISTER. "Normal" proposed
• rulemaking actions are mailed directly to the FEDERAL REGISTER
Officer from the R.A. All other rulemaking actions are routed
I through MOD as shown in Figures 3 and 4 (pgs. 29-30).
5.5 Assistance to Regional Offices by Headquarters staff Offices
• Upon reouest of a Regional Office, EPA staff offices will
continue to provide advance comments on any draft SIP revision
•
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prior to signature by the Regional Administrator. Also, appro-
prlgto ct2ff Affirm wiTj oeriodicallv review and qive comments |
to the Regional Offices on the quality of the FEDERAL REGISTER _
packages they have been preparing and make suggestions for future *
improvements. Where national policy is?iipc do noi- exist but •
several regions are developing individual regulations for similar
sources, appropriate headquarters offices (CPDD, OTLUP, DSSE, etc.) J
will monitor development of these regulations and inform the
Regional Offices which other Regions are working on similar •
regulations. Such regulations might relate to, for example, AQMPs, •
TCPs, or attainment related plans. Any additional assistance requested
will be provided commensurate with availability of resources. Such •
solicitation of comments will not, however, abrogate the authority
and responsibility of the Regional Administrator, nor will receipt 8
of comments from headquarters staff offices require the R.A. •
to act in accordance with the comments or relieve the Regional
Administrator from the requirement to obtain concurrence at •
the Assistant Administrator level on special action SIP revisions.
6.0 PROCESSING OF NORMAL SIP REVISIONS I
6.1 Proposed Rulemaking •
SIP revisions classified as normal will be processed as
depicted in Figure 3. If substantive or procedural problems occur •
with a State-submitted SIP revision (submittal contains major defi-
ciencies), the P.O. will negotiate with the btate as discussed in |
Section 3.2. The proposed rulemaking package shall be signed by «
the Reoinnal Administrator.
The proposal should adequately describe the content o^ the •
proposed revision, anu Taentiry rcdjoi issues so truu iiiLn «•-•:> ..to
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•
•>•>'"';"»'; •. r> i .• ->' r-" ; •- *•!>•: s> . opf; r>r." i'.'paet s;'1" i.bc proposal; 'hen, if
fu^ier v~? '' v: -leered. T hi- pis' can be ^vieved at the ioertified
iorrt 'c.'!t uee Daqp ')}. -- "•& important tc prepare the prcpose.l
I os soon -s ut
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and regulatory sections, but not the action tnerno. It is not •
necessary for them to be sent a copy of the State submission.)
a. Other appropriate EPA offices (See Section 5j. •
Once the proposed rulemaking package has been received by •
0PM ( James Parker, FEDERAL REGISTER Officer), it will be forwarded
directly to the FEDERAL REGISTER without further review or delay. I
It is expected that these actions will appear in the HEDERAL
REGISTER in 5 to 10 working days after receipt by Mr. Parker. If 8
you have any questions on the status of a particular package, please •
call Mr. Parker at 202-755-0830. ™
6.2 Handling Public Comments I
Receipt of any comments shall be promptly acknowledged. A
copy of all comments will be forwarded to the Public Information |
Reference Unit (specify date and page of FEDERAL REGISTER referred _
< I
to; e.g., XX FR XXXXX, X/X/XX) at the previously mentioned address. m
The Regional Office will take substantive comments into proper I
consideration as to how they impact on approval /disapproval and
proposal actions. In preparing the final rulemaking FEDERAL REGISTER |
package, these public comments must be discussed in the preamble to _
the final regulations to be published in the hEDERAL REGISTER package, ™
along with EPA's response to such comments. If no comments were •
received,, "it must be so noted.
^ • 3 f J QjLL JiMlfEilllnS, I
Final .Mk making for normal SIP actions will be processed as —
shown i -. F •.:.!,. i • '-"•"-si r ilr! skip'1 action
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30 dc.y public comment period. Thus, as discussed in Section 6.2
• the regional Office v/i 11 consider substantive comments on the
— proposed rulemaking action and discuss these in the action memo-
* random and preamble of the final rulemaking action along with EPA's
• :'£buci'se to such comments. As discussed in bection 3.1, the final
FEDERAL REGISTER package shall include the action memo, regulatory
I portion, and rationale for approval/disapproval.
The Regional Administrator shall forward the final rulemaking
• package through MOD (James Parker) to the Administrator for signa-
• ture with copies to PIRU, CPDD, DSR and other appropriate head-
quarters offices as discussed in Section 5.0. As shown in Mgure
I 2 (Section 3) the package forwarded to MOD shall consist of the
cover memo, the action memorandum (original and I copy), the
• preamble and regulatory portion (original and 8 copies) and
• attachments (2 copies).
6.4 Procedure for Headquarters to Change a Normal Action to a
I Special Action Issue
If a staff office feels that a proposed rulemaking action
• classified as normal by a Regional Office should be a special
• action rulemaking, this office may recommend that the appropriate
Assistant Administrator consult with the Regional Administrator
• on the need tor special action on the rulemaking. A memorandum
from the Assistant Administrator should be forwarded to the Regional
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Administrator (cc ORIO) prior to the end of the 30 day comnent
period on the proposed ruler^ing. Tf e Recicria"! /"dr irrist rater •
and involved AAs shall reach agreement as to whether the •
rulemeking action will be treated as a normal or special action
SIP re\ -'sicr, at the final rulemaking stage, and it shall be pro- I
cessed accordingly.
7.0 PROCESSING OF SPECIAL ACTION SIP REVISIONS I
Rulemaking for SIP revisions classified as special action •
will be processed as depicted in Figure 4. If substantive or
procedural problems occur with State-submitted SIP revisions, the I
R.O. will negotiate with the State as discussed in Section 3.2.
7.1 Proposed Rulemaking Action |
The proposed rulemaking will be signed by the Regional •
Administrator and forwarded to the Office of Regional and
Intergovernmental Operations (ORIO) (attention: Mr. George I
Alexander (A-101) EPA, 401 M Street, S.W., Washington, D.C.
20460). Copies of this transmittal , with appropriate technical |
documentation (including the State submission and summary of _
State hearing if applicable) will be simultaneously forwarded "
to the appropriate headquarters staff offices for review, ORIO •
will hold the proposed rulemaking package for 14 calendar days
from receipt. During this time, ORIO will notify the appropriate |
staff offices of the time limits of the review period by
telephone. At the end of the period, if no non-concurrences have •
been received from an Assistant Administrator or the General •
Counsel, concurrence will be assumed. ORIO will notify the P. A.
and forward the package to OPM/^OD for transmittai to t^e
REGISTER.
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i -:. J „., i •;.. '-eve- c . i'.c-nt
• ..*;••: '•'(•(? <"T 7 ""H: •uVicus -•"!-'-!>-' "PC'* o' i'ost special actler
4".sut'5,. w?',v Keyluid i Off-ice should nc/'Mn'ly summarize the infor-
• nation i deluded *r\ the proposal and irnl'e this Information available
_ „ , .,,;.,,, s re]ease to newspapers cf qeneral circulation atter
concurrence by headquarters staff offices.
I ^. 3 Handling Public Corrments
Public comments will be received by the Regional Office and
| acknowledged. A summary of these comments will be included and
• discussed in the preamble of the final rulemaking package. If
no comments were received, it must be so noted. The RO will forward
• one copy of all public comments to the Public Information Reference
Unit. The Regional Office will supply copies of these public
| comments to headquarters offices only upon request.
• 7.4 Final Rulemaking Action
The final rulemaking (promulgation) for special action SIP
I revisions will be forwarded by the Regional Administrator to the
Administrator via the Office of Regional and Intergovernmental
I Operations. As shown in Figure 2 (Section 3) the package shall
_ consist of the action memorandum (original and 1 copy), the
* preamble and regulatory portions (original and 8 copies), and
• attachments (2 copies). Copies of this submittal will be
simultaneously forwarded by the RO to the appropriate staff
I offices for review. ORIO will again hold the package for 14
calendar days from the receipt. During this time ORIG will
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opies to rpDronriete review r-ffices.
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notify the appropriate staff offices of the time limits of the |
review period by telephone. At the end of that time, if no
non-concurrences have been received from an Assistant Adminis-
trator or the General Counsel, QRIO will notify the R.A. and forward •
the package through MOD to the Administrator for signature.
The headquarters staff review will be restricted to national |
policy implications. There will be no provisions for a staff _
office to recommend changes to the formal proposal or promul- •
gation package unless the changes are of sufficient importance to •
warrant a formal, written, non-concurrence by the appropriate
Assistant Administrator or the General Counsel. I
7.b Non-Concurrence
If a non-concurrence is warranted at the proposal or final •
rulemaking stage, the Assistant Administrator or General •
Counsel will forward it to the Regional Administrator with a
copy to ORIO. ORIO will provide appropriate staff offices with •
copies of the non-concurrence. The Regional Administrator will
initiate actions as appropriate to resolve the issue. Upon •
resolution, ORIO will inform the other appropriate offices. •
If the non-concurrence is resolved by revising the original
FEDERAL REGISTER package, the revised package will be resubmitted I
through the concurrence procedure.
If an agreement cannot be reached, the Regional Office will I
prepare the package with the non-concurrence memorandum tabbed H
and transiri ;: the package to the Administrator IHrounh °PT", with
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1
• Figure '^ PPOCOli;
|r _.
JK.O. »-eceivfft o* •
p '"60 ere*; revision
1. ._.T _j
iLiaaS^ _1-.L.-IIIIIB»« !!!••• -•"•=*
4^§^»" -« ™««-J-»w-™™»w» -»,M»™n — ,Jta— : H -
w
R,r signs PRK arid ~~j
|j-^'rr_ '?''° —J
. _ -J
t
1
1
\'
Cover memo and PRMa
to 0PM /MOD
1
" PRM published in
— FEDERAL REGISTER
1 i
R.O. evaluates comments
Iand prepares FRM
1.
|
rr>M +-n nnw /wnn 1
rKn tO Urn/rlUU P
* NOTE: PRM - proposed rulemak
FRM - final rulemaking
I a. This package includes a
original and 1 copy; pre
• and 8 copies; and attach
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1
'r-s '-^- i'S^k. >: ' LVisicr:
- -^4r f St ate Pe vi s '( on ronta": n?
-•ojor Deficiency, RO necjo-
jtiates with State for acc-
leptabic changes
Copies of cover memo, PKM,
technical documentation
nary of btate hearing if
appropriate) to PIRU, CPDu,
and DSR, and to DSSE, OIL UP,
MSED, and OGC as appropriate
Copies of Action Memo, FRM and
•^ additional or revised backup
material to PIRU, CPDD and DSR,
and to DSSE, OTLUP, MSED and
OGC as appropriate
rKF! to AX for Administrator s signature
\b
| FRM to OHM/MOD
t
ing FRM published in
FEDERAL REGISTER
cover memorandum, action memorandum,
ambit and regulatory portion, original
ment, 2 copies.
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Figure 4. PROCEDURES hOR SPECIAL ACTION SIP REVISIONS
iR.O. receives or 1 ^
[prepares revision J
*^
RA signs PRM and
cover memo
JCC to ORIO |<
^
x'""
PRM published in
Federal RfcKjislyr ^^ .......
•^
R.u. evaluates comments
and prepares FRM
deficiency, RO negotiates with State
for acceptable changes
Copies of cover memo, PP.M, and technical
1
1
1
documentation to PIRU, CPDD, DSR, OGC,and| •
to DSSE, OTLUP^ and MSED as fpB£flB£l4& J •
f AA non-concurrence to RA within 14 days 1
lo'ver1' |7iern0j e£c> ^0 (JUIO.^ OR16 forwaros
to OPM/MOD after 14 days, or after
resolution of non -concurrence is^e
Copies of Action Memo, FRM, and additions
or revised backup material to PIRU, CPDD
DSR, and OUC, and to DSSE, OTLUP, and
MSED as appropriate
CC to ORIO_Kj[ AA non-concurrence to RA within 14 davs
n
Action Memo, etc. to ORIO. ORIO forwards
to AX- through MOD after 14 days, or after
resolution of non-concurrence issue
Y
hKM to AX for Administrator's signature
^
!FRM to OPM/MOD !
f
hRM published in Federal Register
NOTE: PRM - proposed rulemaking
FRM - final rulemaking
Boxes in heavy outline contain the headquarters staf+ rev lev;
a. This package includes a cover memorandum, action memorandum,
original and 1 copy; preamble and regulatory portion, original
and 8 copies; and attachment, 2 copies.
30
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N O 33
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GUIDELINE SERIES
OAQPS NO.
1.2-011
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GUIDELINES FOR DETERMINING THE NEED FOR
PLAN REVISIONS TO THE CONTROL STRATEGY
PORTION OF THE APPROVED
STATE IMPLEMENTATION PLAN
VS. ENVIRONMENTAL PROTECTION AGENCY
Office of Air Quality Planning and Standards
Research Triangle Park, North Carolina
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TABLE OF CONTENTS
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A. Plan Revision Documentation .............. 26
«B. Notification of State and Public ............ 26
1' Federal Register Notice .............. 27
2. Other Federal Register Actions ........... 32
3. Letter to the Governor ............... 33
I. Introduction 1
II. Responsibilities in Implementing Plan Revisions 5
A. Regional Offices 5
B. Headquarters 7
C. Alternate Responsibilities 8
III. Procedures for Determining Whether a SIP/Control
Strategy Needs to be Revised 10
A. Identification of Problem Air Quality Control Regions . 10
B. Review of Specific Conditions within Individual AQCR's . 14
1. Evaluation of Data 15
2. Analysis of Control Strategy 18
3. Available Analytical Techniques 21
(a) Abbreviated Roll-back Procedure 21
(b) Modified Roll-back 23
(c) Diffusion Modeling . • 23
C. Determination for Need for Plan Revision 25
IV. Procedures for Requiring Plan Revision 26
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«V. Overview of Necessary Action in Relation to Substantially
C. Plan Submittal ..................... 34
Overview of Necessary Action in Relation to Substantially
Inadequate SIP's ...................... 35
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I. INTRODUCTION
Section 110 (a)(2)(H) of the Clean Air Act, as amended requires
• that State Implementation Plans (SIP's) provide "for revision, after
public hearings, of such plan (i) from time to time as may be necessary
^F to take account of revisions of such national primary or secondary ambi-
tifc ent air quality standard; or the availability of improved or more expe-
ditious methods of achieving such primary or secondary standards; or
H (ii) whenever the Administrator finds on the basis of information avail-
able to him that the plan is substantially inadequate to achieve the
^ national ambient air quality primary or secondary standard which it
^ implements". (Emphasis added)
^ While the Act specifically identifies two reasons why SIP's can
ft and must be revised, this guideline deals mainly with the second category,
i.e., plan revisions to the SIP which are deemed necessary on the basis
of information which indicates the approved SIP control strategy is sub-
stantially inadequate to attain and maintain the national standard it
implements.
•| It is the Regional Administrator's responsibility to identify any
SIP which is substantially inadequate to attain national standards and
j^l to call for a plan revision where necessary. Such determinations are
•to be made in Fiscal Year 1976 for all areas of the nation (i.e., both
AQMA's and non-AQMA's) for each criteria pollutant (i.e., TSP, S02> CO,
0 and N09). Calls for revision to those existing SIP's which are sub-
X c,
stantially inadequate for attainment must be publicly announced without
proposal prior to July 1, 1976. These calls for revisions must specify
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the schedule for submission of revisions and must require that, to the
extent needed to meet national primary standards, all emission limitations
revision for attainment of national standards shall also consider
maintenance of such standards.
*Thus "technology forcing" based upon reasonable (not crystal ball) projec-
tions should be required wherever necessary to attain and maintain the
primary standards.
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which it is reasonable to anticipate will be achievable within a reason- A
able period of time must be submitted by the State by Ouly 1, 1977.* Any
other control measures (generally referring to transportation controls I
and land use measures) necessary for attainment and maintenance must be
submitted by the State by July 1, 1978. (NOTE: This is not intended to •
imply that some land use and transportation measures are not considered ^
reasonable. These measures, though considered reasonable, generally |i
require more time to implement due to need to obtain enabling legislation.) ^t
While the Act requires attainment of both primary and secondary
standards, priority attention shall be addressed to attainment of primary H
standards. However, it is recommended that when plan revisions are
called for attainment of primary standards that they also be adequate H
to provide for the attainment of secondary standards. Further, any plan —
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The decision to call for a plan revision should be made only after
detailed analysis of the status of air quality; the restrictiveness •
of the existing regulations; the status of major compliance actions and
after thorough discussion with all pertinent program elements in the
Regional Office and with the affected State and local control agencies.
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The Agency must exercise good judgment in determining whether the
• control strategy portion of an approved SIP is inadequate to achieve
national standards on a timely basis. It is the Agency's policy to
• request such plan revisions only where they are clearly necessary. To
•declare that a SIP is substantially inadequate will imply a need for
new and more stringent emission limitations. It will take some time to
• develop such limitations. Pollution sources might use this situation
to resist coming into compliance with existing regulations and thus,
• ongoing abatement actions could be inhibited. Further, frequent revisions,
_ particularly where they affect emission control requirements, are unde-
™ sirable in that they confront source owners with a "moving target".
Wi Another factor to be considered is that any plan revision submitted
by a State that changes some part of the SIP or which adds a new part
H could result in a Section 307 challenge by the affected sources to the
,^. changed or added part. Such action may1del ay enforcement of the new
^ requirements. (Section 307 provides for a process of judicial review of
Hj the Agency's action in approving or promulgating any implementation
plan or revision thereof.) The Office of Enforcement's experience
with s307 suits indicates that substantial delays in enforcement can
result from such challenges. Therefore, this reason alone is good
cause to minimize changes in regulations in the plan until present con-
Hi trol requirements are fully implemented and any revision is clearly
necessary.
This guideline addresses the procedures to be followed in determining
those areas that mav not attain national standards (i.e., both Air
Quality Maintenance Areas (AQMA's) and non-AQMA's). Once it has been
determined that a SIP is substantially inadequate, the degree of analysis
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needed by the State to demonstrate attainment and maintenance varies depen-
ding upon whether the area is designated an AQMA or not. The analysis
procedures for AQMA development are found in Part 51, Subpart D (Main- •
tenance Regulations). These Maintenance Regulations will allow the
Regional Administrator to modify certain analysis requirements by follow- •
ing specified procedures. Procedures for States to demonstrate attainment ^
in non-AQMA areas are those existing Part 51 regulations on SIP 9
development. ^
This guideline does not address procedures for areas where only
a maintenance plan (i.e., no attainment plan necessary) is needed. •
Procedures for such maintenance plans are found in Part 51, Subpart D
(Maintenance Regulations). It should be noted that calls for SIP H
revisions where only a maintenance- plan is needed (i.e., where no ^
attainment plan is needed) need not be accomplished by July, 1976. 9^
The Regional Administrator may schedule the call for a maintenance plan J*
at any time for those areas that do not have an attainment problem but '^^
which may need a maintenance plan. |H
This guideline sets forth (1) the responsibilities of headquarters
and Regional Office personnel in relation to determining the need for
and calling for plan revisions, (2) the procedures for determining when
a plan revision to the control strategy portion of the SIP is necessary,
and (3) the procedures for notifying the State that a plan revision is
necessary. EPA procedures for approving/disapproving SIP revisions
submitted by States are not included in this Guideline but are contained
within OAQPS Guideline 1.2-005A (as revised).
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RESPONSIBILITIES CONCERNING PLAN REVISIONS
A. REGIONAL OFFICES
The Regional Office is responsible for reviewing available infor-
mation to determine if the approved control strategy is substantially
inadequate to attain and maintain the national standards. In making
this determination, it is important that the various program elements
within the Regional Office (OAHM, S&A, OE) be involved in the evalu-
ation and decision-making process. The various activities
required to determine the adequacy of the approved SIP generally involve
the responsibilities of these three Divisions. For example, the analysis
to determine the inadequacy of the SIP requires (1) a determination of
the validity and representativeness of the ambient air quality data
(S&A activity), (2) a determination of which portions of the control strategy
need to be revised and what new regulations should be recommended (OAHM
activity), and (3) a determination of the impact of these recommended regu-
lations on on-going enforcement activities (OE activity). Interdivisional
coordination is therefore essential to make the most effective call for
plan revision. Similarly, coordination, as appropriate, with State and
local agencies can also result in a more effective plan revision.
Specific Regional Office responsibilities require that each SIP
for each pollutant (i.e., particulate matter, sulfur dioxide, carbon
monoxide, photochemical oxidants and nitrogen dioxide) be reviewed during
Fiscal Year 76 to determine if any such SIP is substantially inadequate
to attain and maintain national standards. In cases where the SIP is
determined to be substantially inadequate, the Regional Office must:
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(1) By July 1, 1976, notify the State, and announce in the Federal
*NOTE: It has been recommended that EPA Order 1270.5 be amended to read
as indicated. Presently the order requires the RO's to obtain the concur-
rence of the AA's on significant plan revisions. The order also presently
states that concurrence should be obtained on other plan revisions.
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Register that the control regulations contained in the SIP for the
pollutant in question are inadequate to attain (and in most cases to i|
maintain) national standards and that a plan revision is necessary. A
call to the State for a plan revision should be as specific as possible 8
in suggesting what new or revised regulations are needed. Further, the
call for plan revision should establish a time schedule for the State to •
submit an indication of its intent to develop the necessary plan revision ^
and also for the submittal of the actual plan revision. (See Chapter IV 9
for additional details.) MB
(2) By July 1, 1977, the State must submit a plan revision that
includes, to the extent needed to meet, national primary standards, all H
emission limitations which it is reasonable to anticipate will be achievable
within a reasonable period of time. Also, any other control measures H
(generally referring to transportation controls and land use measures) _,
necessary for attainment and maintenance must be submitted by the '^P
State by July 1, 1978. ^f
On October 15, 1973, the Administrator delegated his authority to ^
request plan revisions from States to the Regional Administrators through Wf
EPA Order 1270.5 (see Appendix C). In cases where a plan revision is
requested by The Regional Office, the Assistant Administrators for OAWM •
and OE should be notified.*
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• Once the plan revision has been submitted by the State, the Regional
Office is further responsible to review, to recommend approval/disapproval
* and promulgation and to prepare the Federal Register package associated
m with any measures which have been determined to be necessary to assure
^' that the national standards will be achieved. These procedures are
• contained in the July 22, 1975 Strelow/Legro memo to all Regional Adminis-
trators and will be incorporated in OAQPS Guideline 1.2-005A for proces-
V sing SIP revisions.
m B. HEADQUARTERS (OAWM/OAQPS/OTLUP AND OE/DSSE/MSED)
^ OAWM/OAQPS/OTLUP will provide policy and technical assistance to the
• Regions concerning the plan revision issue. OAQPS has prepared various
policy guidelines concerning operational procedures and the criteria
J^ to be considered in calling for plan revisions. Various technical
^ documents are also available to assist in the analysis of the adequacy
^* of the existing control strategy. For example, many of the technical
•| guidelines prepared primarily for the development of maintenance
plans such as Volume 11 and Volume 12 dealing with data analysis
and modeling respectively can be of value when considering plan
revisions for the attainment and maintenance of national standards.
In addition, guidance on control regulations and "cookbook" type manuals
•I that provide step-by-step guidance on the development of approvable SIP's
for NO and Ov will be provided during the Fiscal Year. Further, OAQPS
A A
will provide additional assistance as appropriate to the Regions in the
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plan revision area.
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The Office of Transportation and Land Use Policy (OTLUP) is
a staff office of OAWM which provides technical support to the Regional ]§
Offices in the development, evaluation and promulgation of transporta-
tion and land use related SIP actions. As such, OTLUP will provide
policy guidance to the Agency on land use and transportation measures
(see August 5, 1975, DRAFT policy memo on subject) and will participate in
the review of such control strategies being implemented by the Regions •
as outlined in OAQPS Guildeline No. 1.2-005A (Revised)
assistance to the Regions regarding enforcement policy with respect to ^
stationary sources and transportation control plan elements, respectively. 9
C. ALTERNATE RESPONSIBILITIES M
The responsibilities within the Agency are somewhat different in
those cases where plan revisions are necessary to take account of new •
or revised national standards. In this case, OAWM has the primary
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responsibility of preparing and publishing in the Federal Register f*
(1) the new or revised national standards and (2) specific guidelines
on what actions States need to take to develop, adopt and submit an
approvable plan to implement the new or revised standard. In general, ••
all States will be required to submit a plan for a new national stan-
dard or will be required to augment and/or revise their existing SIP's
to consider a revised national standard. After OAWM has published
guidelines for the development of approvable SIP's, the Regional Offices
are then responsible to assist States in the development of SIP's, to
develop plans where States fail, etc.
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In situations where the SIP regulations (40 CFR Part 51) are modi-
fied in such a way as to affect the control strategy requirements (such
as the action in relation to maintenance of standards, 40 CFR 51.12,
June 18, 1973) OAWM and Regional Office responsibilities are identical
to those described for a new or revised standard.
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III. PROCEDURES FOR DETERMINING WHETHER A SIP/CONTROL
STRATEGY NEEDS TO BE REVISED
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A. IDENTIFICATION OF PROBLEM AIR QUALITY CONTROL REGIONS
It is difficult to develop comprehensive guidelines for all cases
on exactly how to determine whether a control strategy will need to be V
revised. While there may be a few situations where it is obvious that
a plan revision is necessary, in general it will be a difficult task to •
determine that a plan is substantially inadequate to attain national ^
standards. The basic problem is to determine whether AQCR's are pro- V
gressing satisfactorily toward attainment of national standards jm
as sources come into compliance with emission limitations contained ™
within the SIP. 4|
Some factors that could be considered in making a determination as
to whether a SIP is substantially inadequate are as follows: •
1. Factors favoring a finding that the SIP is not substantially
inadequate:
a. Available data provide a reasonable expectation that
NAAQS have been or will be achieved by the currently approved
SIP under provisions of the existing control strategy. 1M
b. The most recent air quality data are below or not far
above NAAQS. H|
c. Much abatement work is ongoing or yet to be completed
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under existing regulations. JP
d. Air quality and emission data are not yet extensive in
terms of time and geographical coverage.
e. Air quality levels have varied erratically up and down ^
in recent years and a clear trend is not yet determinable.
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f. Emission control regulations have been made more stringent
or more compehensive in the past 1 to 3 years but are not yet fully
implemented.
g. Existing regulations are very stringent -- at or border-
ing on a requirement that all reasonable control measures thst can be
achievable are being used.
h. Major reductions in emissions have been made in the past
year or two and perhaps more reductions are programmed for the
near future.
i. The governmental air pollution control program has grown
substantially in the past few (1 to 3) years and enforcement
actions are being intensified.
2. Factors favoring a finding that the SIP is substantially inadequate:
a. There is good evidence that compliance with existing
regulations will not result in achieving NAAQS by the existing
attainment date.
b. Recent air quality levels are substantially above NAAQS.
c. Most existing regulations have been fully implemented;
future improvement in air quality under existing regulations
will not be substantial.
d. Air quality levels over the past few years show an evident
trend which, in consideration of abatement yet to occur, shows
clearly that NAAQS will not be attained by existing control
measures.
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e. Air quality and emission data are generally accurate
and extensive as to time series and geographic coverage. •
f. Emission control regulations have not changed greatly —
in recent years. m
g. Existing regulations are not particularly stringent •
and do not include all emission limitations which it is reasonable •"
to anticipate will be achievable within a reasonable period of time. •
h. There has not been much change in air quality over the
past 1 to 3 years (and levels are above NAAQS). •
i. Governmental control activities have been reasonably
adequate for the past few years (1 to 3) and regulations are |l
probably enforced well. jm
Of course, a number of factors other than air qualtiy and emission
data must be considered in the determination of the need fo_r a plan •
revision, and/or the timing of the call for plan revision. These factors
include the following:
1. The Clean Air Act requires that SIP's which are substantially
inadequate to attain national standards be revised. Simply because
ambient air quality data exceed a national standard by 10% or 15% does
not in itself indicate an immediate need for a plan revision. Clearly,
the normal variation of ambient air quality due to meteorological condi-
tions, etc., may cause such a condition to exist. The requirement of
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substantially inadequate provides the Regional Office with flexibility JH
in assessing the need for, and especially the timing of a call for plan
revision.
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2. The Agency has submitted to Congress a number of amendments
to the Clean Air Act. The most pertinent amendments affecting the call
for plan revisions involve:
(a) The TSP Act Amendment, and
(b) The Transportation Control Plan Act Amendment.
These two amendments are very similar and if accepted by Congress,
it is anticipated that they would provide extensions to attain the
national standards and provide guidance with respect to those areas
where unreasonable controls are needed to attain standards. Additionally,
the Senate is considering a new Section 120 to the Clean Air Act which
would require the establishment of a planning organization in any area
where SIP's are inadequate to attain and maintain NAAQS. Since these
amendments are presently being discussed by the Congress, calls for
plan revisions should be postponed until after the amendments are
fully considered and adopted by the Congress. It is presently estimated
that the revised amendments may be available toward the latter part of
1975. (NOTE: It is recommended that calls for plan revision be post-
poned, however the analysis necessary to determine the extent of the
^* problem should proceed.)
JH 3. In some cases, little or no ambient air quality data exist
to allow for a determination of the adequacy of the SIP. For example,
in many cases, nitrogen dioxide data may not be available due to the
controversy concerning the original reference method. While adequate
and sufficient data should exist in many major urban areas (due to the
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B. Review of Specific Conditions within Individual AQCR's
To attain national standards, EPA policy is that air quality levels
special field projects over the past few years) there may be some areas ' •
where sufficient data are not available. In these cases, any decision on
attainment and the need for plan revisions ,may have to be delayed from •
the Fiscal Year 76 time period.
throughout an AQCR must be equal to or below (i.e., better than) national
standards (see OAQPS Guideline Document 1.2-008, Revised August 22, 1974). •
In many cases, much of an AQCR may have ambient air quality at or below
the national standards, however, a few sites may have air quality that •
is above the national standards. A review of the specific conditions that —
cause these high ambient concentrations on a site-by-site basis will allow IP
the Agency (a) to determine if a p>an revision is necessary, and (b) to -jm
call for plan revisions that address localized problem areas. Control ^^
strategy revisions based on site-by-site reviews may not be possible in •
many large urban areas, especially for particulate matter, where non-
attainment of standards may be a relatively widespread problem with perhaps H
more than 50% of the monitoring sites above the national standard. In ^^
these cases, it is more appropriate to review the entire control strategy ^P
for the area (i.e., AQCR, county or some other geographic area). It is
suggested, however, that even in such urban areas each site be
examined to determine the quality of data being collected and to determine ifl
if local sources excessively bias ambient measurements.
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Prior to the review of the adequacy of the control strategy, it
is important to investigate the available ambient air quality to deter-
mine (1) its validity and (2) its representativeness (i.e., what does
the data represent and how should such data be used as the basis for
requiring a plan revision?).
1. Evaluation of Data
The validity of the air quality data is a major item in the review
of potential problem sites. Monitoring and Data Analysis Division, OAQPS,
has prepared several guidelines to assist in the certification and inter-
pretation of air quality data (See Appendix B).
While EPA should generally be confident of the validity of the air
quality data submitted by State and local agencies, it is also necessary
to review the validity of specific data, especially those data which
indicate the need for a plan revision. The National Air Data Branch (NADB)
periodically questions State and local agencies concerning aoparent data
anomalies via a form letter; however, a more thorough investigation of the
ambient data which indicates a problem would be conducted by the Regional
Office. The Regional Office should refer to the guidelines mentioned above
for the specific items that should be reviewed to assure valid data.
Briefly, the review should determine:
(a) Are the proper numbers and kinds of monitoring equipment
operating in the area?
(b) Are monitoring sites properly located in accordance with
published guidelines?
(c) Are they properly calibrated and properly operated?
(d) Are the collected data properly validated?
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(e) Have all abnormal values been checked? B
(f) Have peak concentrations which are of most concern been
evaluated to determine their accuracy? •
(g) Are the data accurate and valid and can they withstand a
legal challenge of their validity? •
In cases where data are questionable, they should generally not be
used in control strategy development. It is anticipated that many Section
307 challenges will be filed in relation to revised SIP's. Therefore, it A
is prudent to base the need for plan revisions on valid and defensible
data. •
If it is determined that the air quality values are valid, then a
further review of the data should be made to determine if the data are
representative and if such data should serve as the basis of a revised
control strategy. The review of the data should attempt to determine
if a nearby source(s) overly impacts on a monitoring site. tf|
The purpose of determining the "representativeness" of the data is
so that the control regulations that will be adopted will affect the H
sources that cause high ambient concentrations. For example, if an
ambient monitor is overly influenced by street dust, it is improbable ^P
that new control regulations which place stringent requirements on
stationary sources will have a beneficial impact on the ambient levels
at the site. Similarly, requiring particulate matter control on fuel ifk
combustion sources may not provide for attainment where recorded ambient
levels in excess of national standards are due to windblown fugitive dust.
It is recommended, therefore, that each site be examined to determine
its "representativeness" for use in the development of a general control
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strategy, and/or to determine the sources which the site does represent.
If a site is source oriented, the data collected at that site should be
used to determine the degree of control that source may need to attain
standards but should not be used as the basis for control regulations
for all sources with the AQCR.
In examining the representativeness of the data, it may be determined
that unusual conditions existed such that the data should not be used in
control strategy development. For example, if the frequency and duration
of inversions and stagnations were unusually high, air quality levels could
be higher than normal. Unusually warm or cold weather will result in a
change in fuel use which may increase ambient levels above normal. If
conditions conducive to higher pollution levels were so unusual as to
not be expected to occur again for many years (e.g., 5 or 10 years), it
may be appropriate to discount high pollution levels occuring during such
rare events. Other examples of unusual events include dust storms, fires
or unusual control equipment malfunction or shut-down which could tempor-
arily cause abnormally high ambient concentrations. Generally, data
collected during such situations should not be_ used_ as_ a_ basis for, requir-
ing additional control erf stationary sources.
In the investigation of air quality data, the Regional Offices,
should obtain the very latest aj'r^ quality concentrations for the site i_n_
question. It may be necessary to obtain these data from the State or
local agency if they are not included in SAROAD. (In these cases, the
new data should be submitted to SAROAD to assure the availability of
the latest data to all users.) The data used for the review of the
adequacy of the SIP need not be for a calendar year, but should represent
the most recent 12 months (or four quarters) for which data are available.
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While OAQPS Guideline 1.2-008 points out that compliance with annual
NAAQS shall be based upon calendar year data, it further points out
that a continued appraisal of air quality on a quarterly basis is
needed to assess the status and progress with respect to the adequacy
of the SIP. Hence, it is not inconsistent with other Guidelines to
use non-calendar ambient data to determine if a SIP is inadequate
to attain standards. •
2. Analysis of Control Strategy
With the addition of the latest air quality data, a comparison of the £
trends in air quality levels at the site in question with the air quality ^
trends noted at other sites within the Region (State, city or other areas ™
where comparable results should exist) should be made. If the increase ^
or decrease is significantly different from that at the other sites, it
would appear that a localized problem exists. •
For the purposes of this guideline, consider three hypothetical
cases: •
Case 1: Assume that one site is above the national standards in an
AQCR. In this case, it is recommended that a review of the emission data jfl
and compliance status of sources within the immediate vicinity of ^H
the site in question (sav within a 1 to 3 mile radius--particulate ^^
matter, sulfur dioxide, and CO; oxidant would require a much larger
area) be made. Points to consider include:
(a) Are all sources, both point and area sources, included in |H
the inventory?
(5) Are some sources presently uncontrolled? If so, are there con-
trol regulations with which these sources must ultimately comply?
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If not, do these sources impact sufficiently on the site to warrant
a recommendation for a plan revision to require further emission
limitations on these sources?
(c) If the sources reviewed in (a) have applicable regulations that
they must adhere to at some later date, is the anticipated emission
reduction adequate to reduce ambient levels to below the standard?
(d) Do the sources reviewed in (a) have applicable emission limi-
tations they must presently comply with? Are the sources in compli-
ance with the regulations? If so, will additional emission reductions
be needed to provide for the attainment of the national standard? If
the sources are not in compliance with the emission limitation, is the
source on a compliance schedule? Should EPA/State enforcement action
be initiated against the source?
(e) Have the source emissions in the vicinity of the site in ques-
tion increased significantly? Is a plan revision necessary to com-
pensate for increases in emissions? What action is needed in relation
to assuring that the State adequately considers ambient standards
prior to approval for construction of new, sources?
Case 2: Suppose the attainment date for an AQCR has passed. If the
air quality data are found to be above the NAAQS, it would seem at first to
indicate that the SIP needs revision. However, the Regional Office should
consider some other items prior to requesting a revision:
a. Are all affected sources in compliance with the SIP?
b. Has sufficient time elapsed for recent emission reductions to
be reilected in the air qualtiy data?
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c. Have any of the sources affecting the site received a variance
from the State? Was such a variance legal? If not, is enforcement
*NOTE: In the Draft of this Guideline that was circulated for review in
August, 1975, a discussion was provided which indicated that the AQCR iden-
tiffed above should be reclassified to indicate that an air quality problem
existed. Many commentors correctly noted that this was contrary to pre-
vious guidance on the recommended use of the Priority Classification System
(8/12 memo from Mr. Steigerwald to Mr. Holman, Region I). Since that memo,
additional discussions have lead to the belief that the Priority Classifi-
cation Scheme is useful and should be retained. Consequently, work is
underway to improve the classification system (e.g., to delete regulatory
requirements associated with it and to revise it to indicate current
Agency priorities). Additional information will be provided to the Regional
Offices for review and comment prior to finalization of a modernized classi-
fication scneme.
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action necessary? •
d. Are new sources affecting the site? Is the State giving proper
consideration to the NAAQS when approving new sources? •
e. Should EPA action be taken to implement new source review
procedures? •
Case 3: Suppose that an AQCR was originally classified Priority III _
because no data were available to indicate if any problems existed. More mr
recent data however show that an air quality problem does exist. What action
should be taken?*
In this case, the regulatory structure of the SIP should fll
be reviewed since the SIP may contain emission control regulations ade-
quate to attain NAAQS. Though the AQCR was classified Priority III, the I
example region approach may have been used for plan development resulting
in the adoption of State-wide regulations. The implementation of these j^
regulations may be adequate to attain NAAQS. ^|
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3. Available Analytical Techniques"
Predictions of future air quality, especially when abatement actions
are still going on or to be taken, are not precise. Therefore, any finding
on what future air quality will be is not precise and a finding that a SIP
is substantially inadequate at this time should consider a number of variables
rather than be based on simplistic calculations. Various analytical tech-
niques are available to assess the source/receptor relationship, and the ef-
fect of emission control limitations on this relationship. Some of these
techniques are described below:
a. Abbreviated Roll-back Procedure
This procedure is useful when the amount of additional emission reduc-
tion expected between the present time and completion of actions to assure
compliance with all existing regulations can be readily calculated, such as
when only a few sources remain out .of compliance. In using this procedure,
the following calculations are made:
(1) Prepare an estimate of the emission reductions that will occur
because of completion of remaining abatement actions. For example,
25 sources may remain out of compliance. Their present emissions
are 140 tons per day. When controlled in accordance with existing
regulations, their emissions will total 40 tons per day (100 tons
not yet control led).
(2) Prepare an estimate of total emissions in the area as of
the present time, either by:
(a) Updating the on-going emission inventory, or
*Though not discussed in detail herein, it is assumed that a current
emission inventory for point and non-point source and source compliance
information is available. Point sources are generally defined as those
sources with a potential for emitting 100 tons or more of a criteria
pollutant.
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(b) Taking the original SIP estimate of emissions after the
control strategy is implemented and add to it the "not yet I
controlled" value from Step 1. For example say that present _
emissions are 1000 tons per day. m
(3) Estimate future air quality after remaining abatement is m
accomplished by use of the proportional model, using the following '"
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formula:
Future AQ _ Present emissions - emissions yet to be controlled
Present AQ ~ Present emissions g|
3 B
assume present air quality is 90 ug/m ™
Future AQ 1000 - 100 •
90 ug/m3" 1000 P
Future air quality = 81 ug/m3 j_
If the pollutant of concern involves a background (rural area) factor, ™
it must be considered. For example, assume the pollutant is particu- A
late matter and background levels are 30. Future air quality is then
calculated, in this example, to be: ^1
Future AQ - Background = 1000 - 100
Present AQ - Background 1000
Future AQ - 30 = 900
90-30 ug/m3 1000
Future air quality = 84 ug/m3
Such a procedure is useful in that it considers current air quality,
emission and compliance information to assess the potential of future
emission reductions. However, other more sophisticated techniques are Ifl
available to relate emissions to air quality. It is generally recom-
4
mended that in determining the need for a plan revision a more detailed
approach be utilized in defining the relationship between emission
reductions and air quality.
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b. Modified Rollback
The modified rollback model represents an improved form of the
• basic rollback model and allows for direct consideration of additional
parameters not considered by the basic rollback model. The modified
• rollback models can be used manually or by computer depending on the
complexity of the study area. They are available in four basic forms
V which are progressively more detailed and accurate and progressively
A require a more extensive data base and computation time.
The first form of the modified rollback models extends the basic
• rollback to multiple categories of sources, which may experience differ-
ing rates of growth and degrees of control. The second modified form
V extends this multiple-source version to include the effects of average
•Mj stack heights for the various categories. The third model includes the
radial distance from source to receptor, and the fourth model adds wind
• direction frequency. The technique is described in a paper entitled
"Rollback Modeling - Basic and Modified" by Noel de Nevers and Roger
|| Morris, and is further summarized in Volume 12 of the Maintenance Guide-
line Series: Applying Atmospheric Simulation Models to_ Air Quality
Maintenance Areas.
•I c. Diffusion Modeling
This is the preferred predictive tool available in relating emissions
to air quality data. A number of diffusion models, Air Quality Display
Model (AQDM), the Implementation Planning Program (IPP), etc., are avail-
able for defining urban situations on an annual basis and are listed in
Table 1 (see OAQPS Guideline Document No. 1.2-031, September 1974 for
detailed discussion). Diffusion models such as these, as well as technical
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Table 1
Summary of Simulation Model Characteristics
Model
Name
Rollback
Appendix J
MUler-
Holzworth
Hanna-
GHford
Hanna-
GHford
Pollutant
Specifi-
cation
Any
°x
SJ,,TSP
2
SO, JSP
CO2
SO, JSP
Averaging
Time
Specifl- Emission
cation Data
Any
1 Hour
1 Hour,
Annual
Annual
1-24 Hour
1
1
1
1
2
Meteor-
ological
Data
1
1
3
2
5
Concen-
tration.
Estimates
3
3
3
3
.
2
Ease of
Use
1
1
1
1
2
Avail-
ab1 1 1 ty
1
1
1
1
1
Rell-
ab1 1 1 ty
3
3
1
1
1
Applicability
to AQM
3 .
3
3
3
2
w. Point Source
model
w. HIWAY
AQDM
SCIM*
APRAC-1A
SAI*
SJj.TSP
co2
S02,TSP
SJ2.TbP
CO
CO,N02,0X
1-24 Hour
1-24 Hour
Annual
1-24 Hour
1-24 Hour
1-10 Hour
3
3
3
3
3
2
5
5
4
5
5
5
1
1
1
1
1
2
2
2
3
3
3
3
2
2
2
3
2
3
1
1
1
2
2
. 2
1
1
1
1
1
2
*1hese models are currently In a developmental and debugging phase; tFey are not available for general
distribution as computer programs.
Key to Table 1
E.
G.
A. Pollutant Specification '
Any pollutant
Specific Pollutant; (so,, TSP, rn, Ox. NO,)
B. Averaging-time Specification
Any averaginq-tlme
Annual Average
1 to 24 hour Average
C. Emission Data
1. Area-wide Emissions Total
2, Total emission distributed as finite area sources
3. Detailed point, Hne and area sources
D. Meteorological Data
1. None
2. Average wind speed
^t Average wind speed and mixing height
\ A', Frequency distribution of wind direction, wind speed,
stability and mixing height
5. Hourly variations of wind direction, wind speed, stability'
and mixing height
H.
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Concentration Estimates
1. Estimates at any specified point
2. One estimate for each area source grid
3. One estimate applicable to entire AQMA
Ease of Use
1. Slide-rule
2. Small computer effort
3. Major computer effort
Availability
1. r--n literature
2. National Technical Information Service
3. EPA, upon request
Reliability
1. Can be verified and calibrated
2. Verification 1s Incomplete, possibility of calibration
Is uncertain
3. Questionable, acceptable for crude estimates only
Applicability to AQM
1. Can distinguish between specific source and land use types
2. Can distinguish between land use types only
3. Considers no distinction between sources or land uses
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assistance to operate them on the EPA UNIVAC 1110 system is available
from MDAD, OAQPS. Point source models are also available for single
source short-term (1-hr and 24-hr) situations. Diffusion modeling
requires detailed emission, air quality and meteorological data to
mathematically simulate the emission/air quality relationship for a
given AQCR. While there are certain limitations which restrict the
use of diffusion models (lack of data, severe topographic variations,
etc.), the method does provide the best available approach to predict
resulting ambient levels caused by the application of emission limita-
tions on emission sources. (see note)
C. Determination for Need for Plan Revision
During the technical analysis to determine if a plan revision is
appropriate, the Regional Office should consider the impact of calling
for a plan revision in relation to ongoing enforcement programs. The
possibility of a Section 307 challenge, and its effect on compliance
and enforcement should be discussed and considered. While plan revi-
sions should be sought where determined necessary, attempts should be
made where possible to minimize the impact of plan revisions on enforce-
ment activi ties.
NOTE: Both rollback and diffusion modeling techniques have been
discussed in this document. It should be noted that the Agency
proposed in the Federal Register on September 14, 1973, that future
control strategy development shall be based upon diffusion modeling
analysis. This position may be somewhat modified prior to promulgation.
Further, additional Jjuidance on modeling techniques will be published in
Appendix A, of the Part 51 regulations. For purposes of preliminary
analysis of the problem AQCR's, rollback techniques may be used; however,
when the" revised control strategy is developed by either the State or
EPA it is strongly recommended that diffusion modeling be utilized
in most cases. In other words, rollback is adequate for the decision
to call for a plan revision but is not as good as diffusion modeling
as the basis of costly regulations that can be challenged under Section 307,
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IV. PROCEDURES FOR REQUIRING PLAN REVISIONS _
If the analysis of the problem indicates that a revision to the
control strategy is needed, the following actions are necessary:
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A. PLAN REVISION DOCUMENTATION
The Regional Office should document the reason why the plan revision .£
is necessary, providing a reasonable amount of detail on the discovery j*
analysis performed to determine the need for the revision. To the ex- ™
tent practical, the Regional Office should suggest specific source(s) •
or source categories or regulations which should be considered under the
plan revision. While it is hoped that the approved SIP will be adequate •
to attain the national standard on an AQCR-wide basis, it is likely that
portions of some AQCR's will need further controls to achieve H
the standards. In other AQCR's, area-wide changes in the SIP will
be needed. Recommendations for SIP revisions should therefore be made as
to the specific geographic area in which the revision is needed, i.e.,
by AQCR, by county, by "hot spot" areas or in some definable area where
an air quality problem has been noted. •
The analysis which is performed to determine the need for a plan re-
vision should be discussed with appropriate State and local officials. •
Similarly, the particular regulations which should be revised or added _mm_
should be identified, to the extent practicable at this stage of evalu- ^P
ation,with appropriate State and local officials. ^|
B. NOTIFICATION OF STATE AND PUBLIC
rf
The Regional Offices should first confer with the State and/or local
agencies involved and advise them of the need for plan revision and explore
with them, any particular regulations which clearly need revision or
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need to be added and those which do not. Subsequently, the Regional Admin-
istrator should officially notify the State that a revision is necessary
via a letter to the Governor followed by a Federal Register notice.
1. Federal Register Notice
Various Federal Register actions will need to be taken in relation to
• advising the State and the public that the Agency has determined that a
— plan revision is necessary. The first Federal Register action involves
™ a Federal Register notice indicating EPA's determination of an SIP defici-
fl| ency and requesting corrective action on the part of the State agency.
The Federal Register notice can be considered as an "open letter" to
• the State and it should contain a summary of the detailed analysis on which
the need for the plan revision is based. Specifically, the notice should
^ discuss the following:
ft &. Specific reasons why the plan revision is necessary;
b. Recommendations as to the actions which appear to be necessary
JH to correct the deficiency, if known, e.g., what sources appear to cause
tthe need for further controls; what regulations, if any, should probably
be revised or added; and which regulations appear to be adequate.
Ik c. The Federal Register Notice should also indicate that the plan
revision should include the degree of emission reduction necessary
to offset emission increases that can reasonably be expected to result
from projected growth of population, industrial activity, motor
vehicle traffic and other factors that may cause or contribute to
increases in emissions; (NOTE: In non-AQMA areas, it is not necessary
to require the detailed consideration of growth as is required for
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AQMA's. In non-AQMA's, the FMVCP, NSPS, and the review of new source
procedures should generally be adequate to maintain NAAQS. However,
*The final 40 CFR 51 regulations for maintenance olan for areas that need
to submit a plan to attain national standards may specify a constraint
on the length of this schedule (such as July, "1978).
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the plan revision should consider growth in an area and, where necessary, B
include the degree of emission control to provide for continued main-
tenance of NAAQS.) •
d. The Federal Register Notice should identify the specific geographic
area within an AQCR where the problem exists. f
e. If the non-attainment area is an AQMA, the Federal Register Notice ^
should inform the State that the plan revision for attainment and main- W
tenance should be developed and submitted in accordance with procedures A
set forth in Subparts A, B, and D and other EPA guidance, and should
provide a schedule under which the full attainment and maintenance plan •
must be submitted.*
f. The other portions of the SIP which may need to be revised as a conse- f
quence of the control strategy revision. These may include portions ^»
required under the following sections of 40 CFR 51: ^^
(i) Section 51.11 Legal Authority—especially if transportation dt
or land use controls are deemed necessary.
(ii) Section 51.15 Compliance Schedules—must be provided if new ^1
control regulations are adopted.
(iii) Section 51.17 Air Quality Survei 11 ance--if the Region has a •§
substantial air quality problem, more ambient sampling may be required
to define the extent of the problem and monitor progress.
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(iv) Section 51.21 Intergovernmental Cooperation—portions may
• need to be revised if the State delegates new responsibility to
f other State or local agencies to carry out portions of the plan.
(v) Section 51.20 Resources—new control regulations may require
ft additional resources for enforcement purposes. Such information
should be reported with the plan revision.
• (vi) Section 51.10 General Requirements--the control regulations
^ submitted as part of the plan revision will probably indicate the
T§ need for a change in the date of attainment of the national
•| standards. The notice should specify that the revision must provide
for the attainment of the primary standards "as expeditiously as
• practicable." Until the Clean Air Act is amended to provide
for extensions of the deadlines, the mid-77 attainment date is
^ still technically the "no later than" cut-off point of the Act for most
^ areas. [A one-year deferral mechanism (i.e., Section 110(f)) exists for
source specific extension cases. However, OE advises that use of such a
H mechanism, because of the requirements of adjudicatory hearings, can be
^^ time consuming and should probably be minimized.]
4 For those few areas with pre-1977 attainment dates in which it
is reasonably certain that a control strategy can be developed which
could attain the standards by mid-1977, the state should be required
H| to submit revisions which will attain the standards "as expeditiously
as practicable," but no later than mid-1977. The state should be told
that it will be necessary to apply formally for a deadline extension
of the original attainment date (e.g., May, 1975) pursuant to Section
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llO(e) and 40 CFR 51.30, If these requirements are otherwise met, an •
extension can be granted if the revised plan requires significantly -
more stringent controls than contained within the original SIP. •
For most areas it will be impossible to identify an appropriate
attainment date in the notice because, although the analysis supporting f
the notice must identify the nature and extent of the problem, an appro-
priate attainment date will not be identifiable until the control strategy
is developed. For these cases, the notice should require the State to
identify a new attainment date, which must be "as expeditiously as practi-
cable", and submit it for approval with the plan revision. (It should •
be noted that this is an interim policy until the Act is amended to
provide new attainment deadlines and/or extension procedures.)
g. The notice should specify the date for submission of the revision.
Section 51.6(b), Revision, states that "the plan shall be revised within
60 days following notification by the Administrator, or by such later date rf|
prescribed by the Administrator after consultation with the State." Since
a control strategy will need to be developed, compliance schedules deter- ^1
mined and negotiated with regulations subjected to a public hearing and
adoption, it appears that six months or more may be needed to revise the H|
control strategy portion of the plan.
The Agency has established firm end dates for the submittal of plan
revisions by States to attain national standards. Plan revisions, containing
emission linitations, shall be submitted by July 1, 1977. In cases where
additional measures are necessary (e.g., land use and transportation controls)
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such measures may be submitted no later than July 1, 1978. It should be
Jj noted that these are "no-later-than" dates and that plan revisions should
• be submitted as expeditiously as practicable. (NOTE: No firm end dates
': exist for areas that need only maintenance plans. The schedule for the
• development and submittal of such plans is to be established by the Regional
Administrators.)
d h. The Federal Register Notice should also request that the Governor of
A the State advise EPA within 60 days of its intention to comply with
~ the request for a plan revision and to set forth a timetable for starting
• and completing each major element of the work to be done in developing the
revision. Major milestones may include (a) the development of the control
^ strategy, (b) preparing draft legislative amendments, where necessary,
^ (c) public hearing dates, and (d) submission of plan to EPA. The State
^ should also advise the Regional Offices of the agencies responsible for the
• development of the plan revision and where appropriate, an identification
• of the responsibilities of each agency when multi-agencies are involved with
^ the development of the plan revisions. The notice should clearly state
^ that EPA will begin to take action to disapprove the pertinent sections of
^* the SIP and/or to develop, propose and promulgate EPA regulations, if the
•| State does not provide an indication of its intent to comply with the revi-
sion notice within the stated time period.
i. The Federal Register Notice should declare that all existing elements
in the plan remain in effect (and are fully enforceable) until the revision
is submitted by the State and approved by EPA or EPA promulgates any needed
revision. In other words, there should always be a plan in effect. Also,
since only the specific regulations that are added or changed by a plan
revision are subject to a Section 307 challenge, it would be prudent
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in those cases where possible, not to change any currently approved
regulations but rather add new regulations to the SIP. However, where
the alternative of revising an existing regulation is clearly superior •
to adding a new regulation, fear of litigation should not deter a
revision of the existing regulation. I
j. The Notice should point out that the plan revision must be submitted
in accordance with the provisions of 40 CFR 51.4, Public Hearings, and f
51.6, Revisions and the other requirements of Part 51. In addition, the g|
Federal Register Notice should contain a justification indicating why »
the finding of a plan deficiency is not subject to public comment at this A
time. OGC believes that the Agency's technical determination of the
necessity for a plan revision does not need to undergo rulemaking procedures •
at the time of calling for a plan revision. The public will have ample
opportunity to comment on the action when the plan revision has been sub- ^
mitted by the State (or when EPA proposes its own remedial measures). As
with other plan submittals, the public must be advised of any plan revision
submission and be allowed to comment on the action. An example Federal rf|
Register notice is provided in Appendix A.
2. Other Federal Register Actions •
In addition to the Federal Register Notice discussed above, other
Federal Register actions need to be taken. These actions depend upon the H|
State's response in relation to the plan revision requirement.
In those cases where the State submits a letter of intent, followed
by a plan revision, no action should be taken to disapprove the original
SIP prior to the review of the SIP revision. After the State submits
its revisions and EPA reviews them, concurrent actions can be taken to
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• disapprove particular parts of the original SIP and approve the new or
revised parts. Such procedure would minimize the paper work involved
• in the preparation of the Federal Register and briefing memo documents,
and avoid discontinuities in the regulatory process.
f In those cases where a negative response or where no letter of
« intent is received from the State in relation to the request to modify
the SIP, or where no plan revision is submitted as required, the Agency
• shall take action in a timely fashion to simultaneously propose disapproval
of the pertinent portions of the SIP and propose EPA substitute and/or
• additional regulations. Such disapproval and regulatory actions should
Iseek to minimize disruptions in implementing acceptable regulations, and
be taken in such a manner so_ that a_ plan remains i_n_ effect at_ a 11 time.
•j Agency procedures for preparation of Federal Register actions
are provided in OAQPS Guidelines Series Document No. 1.2-005A
H (revised).
_ 3. Letter to the Governor
^1 It is recommended that a letter be sent to the Governor(s) of the
•| affected State(s) of the necessary action prior to publication in the
Federal Register. Since some explanation of the reason for the plan
II revision is in order, it may be appropriate to attach a draft copy of
the Federal Register notice.
The State Agency should also be advised of the pending Federal Register
action. However, since the State should already be intimately aware of
the content of the call for plan revision from ongoing discussions with
them on the attainment problems, the letter to advise them of the
publication of the notice in the Federal Register is more of a courtesy.
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C. PLAN SUBMITTAL
Once the plan revision is submitted by the State, the Agency pro-
cedures outlined in the OAQPS Guideline No. "1.2-005A govern the review I
and approval/disapproval process.
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V. Overview of Necessary Actions in Relation to Substantially
Inadequate SIP's
The purpose of this Chapter is to provide an overview of the
necessary actions in relation to identifying substantially inadequate
SIP's and calling for Plan Revisions. While this guideline thus far
has discussed procedures to be followed for all areas of the nation
to determine if a SIP is substantially inadequate, certain follow-up
actions are different, depending upon whether an area has been designated
as an AQMA (Air Quality Maintenance Area) or as non-AQMA. Consequently,
two slightly different flow charts that sequentially identify the necessary
actions are provided for AQMA's (Table 2) and non-AQMA's (Table 3). These
minor differences can be seen in Steps 1 and 4 and result from specific
activities and requirements for AQMA areas that do not exist for non-AQMA
areas.
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TABLE 2
ACTION STEPS FOR AQMA AREAS WHERE SIP'S ARE SUBSTANTIALLY INADEQUATE. TO
ATTAIN NAAQS
STEP 1. RO's, with State and local agency assistance as appropriate, determine
those areas of the nation for each criteria pollutant where the SIP is
substantially inadequate to attain NAAQS. Determination by 7/76.
(RO's may wish to use as input the AQMA analysis proposed (in the main-
tenance regulations) to be submitted by the State to EPA by April, 1976.)
STEP 2. RO discusses findings of analysis with State and local agencies and
determines which control regulations should be modified or added by 7/76.
STEP 3. RO advises Governor of State by letter of necessary plan revision by 7/76.
STEP 4. RO publishes a FejteraJ Register Notice (without proposal) to publicly
announce need for plan revisioTi, by 7/76. Proposal indicates among
other things that all emission limitations (as needed) which it is
reasonable to anticipate will be achievable within a reasonable
period of time must be submitted by 7/77, other measures (e.g. , land
use and transportation measures) by 7/78 and a requirement that the
State notify EPA within 60 days of its intent to propose and submit
plan revision. Further, RO should advise State that plan revision should
be developed in relation to Subpart D and other EPA guidance for mainten-
ance area. Also, since the final 40 CFR 51 regulations for maintenance
plans may specify a constraint (such as July, 1973) for subir.ittal of
maintenance plans in non-attainment AQMA's, this should be noted in the
Federal Register.
STEP 5. State submits to RO within 60 days letter of intent with schedule for
completion of major plan items to develop plan revision. If no response,
RO proposes plan revision to attain and maintain "1AAQS in a timely
fashion.
STEP 6. State submits, by 7/77, plan revision with adopted regulations.
STEP 7. RO notifies public of 7/77 plan submittal in the federal Register, seeks
conitients and proposes to approve or disapprove 7/77 plan su'jraittal.
STEP 8. RO approves 7/77 plan submittal, or disapproves and proposes EPA substi-
tute regulations.
STEP 9. Where necessary, State submits by 7/78 other control measures needed
to attain and maintain national standards, such as land use and trans-
portation control measures.
STEP 10. RO notifies public of 7/78 plan submittal in the Federal Reqis_te_r. seeks
comments arid proposes to approve or disapprove 7//8 plan submittal.
STEP 11. RO approves 7/78 plan submittal or disapproves and proposes EPA substi-
tute measures.
NOTE: (1) Dates do not apply to those AQWs where only a maintenance plan
is required. In such cases, the Regional Administrator can establish
any date for submittal of a plan that considers maintenance only
(i.e., not attainment and maintenance).
(2) All dates are latest dates acceptable for this sequence of events.
(3) Step 1, 2, 3 and 4 all have end dates of July 1976. It should be
noted that such steps are sequential and require time between steps for
implementation. It is recommended that these steps be spread out from
April to July, 1976, hoc/ever Regional Offices have the latitude to
establish interim dates as they consider appropriate., Only the July,
1976, notice to the States of a need for a plan revision is a firm
Agency date.
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TABLE 3
ACTION STEPS FOR NON-AQMA AREAS WHERE SIP'S ARE SUBSTANTIALLY
INADEQUATE TO ATTAIN NAAQS
STEP 1. RO's, with State and local agency assistance as appropriate,
' determine those areas of the nation for each criteria pollutant
where the SIP is substantially inadequate to attain NAAQS.
Determination by 7/76.
STEP 2. RO discusses findings of analysis with State and local agencies
and determines which control regulations should be modified
or added by 7/76.
STEP 3. RO advises Governor of State by letter of necessary plan "
revision by 7/76.
STEP 4. RO publishes a Federal Register Notice (without proposal) to
puolicly announce need fbrplan revision, by 7/76. Proposal
indicates among other things that all emission limitations (as
needed) which it is reasonable to anticipate will be achievable '
within a reasonable period of time must be submitted by 7/77,
other measures (e.g., land use and transportation measures)
by 7/78 and a requirement that the State notify EPA within 60
days of its intent to propose and submit plan revision.
STEP 5. State submits to RO within 60 days letter of intent to
develop plan revision with schedule for completion of
major plan items to develop plan revision. If no
response, RO proposes plan revision to attain and main-
tain NAAQS1 in a timely fashion.
STEP 6. State submits, by 7/77, plan revision with adopted regulations
up to RACT (as needed) .
STEP 7. RO notifies public of 7/77 plan subrnittal in the Federal Register,
seeks comments and proposes to approve or disapprove 7/77 plan
submittal .
STEP 8. RO approves 7/77 plan submittal, or disapproves and proposes
EPA substitute regulations.
STEP 9. Where necessary, State submits by 7/78 other control measures
needed to attain and maintain national standards.
STEP 10. RO notifies public of 7/78 plan submittal in the Federal Register.
seeks comments and proposes to approve or disapprove 7/78 plan
submittal .
«STEP 11. RO approves 7/78 plan submittal or disapproves and proposes EPA
substitut m
NOTE:
(1) All dates are latest dates acceptable for this sequence of events.
(2) Step 1, 2, 3 and 4 all have end dates of .lnb/ 1976. U should be
noted that such steps are sequential and require time between steps for
implementation. It is recommended that these steps be spread out from
April to July, 1976, however Regional Offices have the latitude to
establish interim dates as they consider appropriate. Only the July,
1976, notice to the States of a need for a plan revision is a firm
Agency date.
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APPENDIX A
(Example Federal Register Notice)
NON-AQMA AREA
ENVIRONMENTAL PROTECTION AGENCY
APPROVAL OF STATE IMPLEMENTATION PLANS
Notice of Required Revision to Part of the State Implementation Plan for
• the Metropolitan Smogtown Intrastate Air Quality Control Region
On May 31, 1972 (37 F.R. 10842), pursuant to Section 110 of the Clean
| Air Act, and 40 CFR Part 51, the Administrator approved the control stra-
Itegy for the attainment of national primary and secondary standards for
suspended particulate matter in the Metropolitan Smogtown Intrastate
A Region. The plan was designed to attain these national standards by date,
(such as June 1975).
• On the basis of recent air qual-ity data submitted by the State in
— fulfillment of the requirements of Section 51.7 (Reports), and from the
™ evaluation of various compliance actions taken by the State to implement
ft "the adopted particulate emission control regulations of the applicable
plan, it is the technical judgement of the Regional Administrator for
• Region III, that the presently approved control strategy portion of the
_ plan for particulate matter (i.e., pursuant to 40CFR Section 51.13) is
^1 inadequate to attain the national particulate matter standards. There-
ft| fore it is necessary to add additional control measures to the plan or
revise one or more existing regulations for control of particulate matter.
Specifically, this finding is based upon a detailed diffusion modeling
analysis of the urban-industrialized section of Southeast Smogtown, (State)
This analysis, which has been summarized in a technical report entitled
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"The Suspended Participate Problem in Smogtown" is available for inspec- |
tion and copying at the Environmental Protection Agency, Region III, H
Curtis Building, 6th and Walnut Streets, Philadelphia, PA 19106, and the •
Public Information Reference Unit, Room 2922 (EPA Library), 401 M St., S.W., •
Washington, D.C. 20460. Copies of this technical report have been pro- .
vided to the appropriate State and local air pollution control agencies •
within the (State).
The mathematical diffusion modelling analysis, summarized in the I
report, indicates that two sources contribute significant particulate _
matter emissions to the atmosphere in southeast Smogtown. Emissions from V
these sources, which include an uncontrolled cement plant and a moderately d|
controlled integrated steel mill, are such that national particulate ^
matter standards are predicted to be violated beyond the scheduled date fl|
of attainment of the national standards (i.e., July 1975). The
report also identifies that the intermittent open burning at various dumps •
and small uncontrolled incinerators contribute to more localized excursions
above the national standards. Based upon this analysis, the Regional Ad- |l
ministrator, Region III, has determined that a substantial (in the range of ^m
30%) reduction of 1974 annual particulate matter emissions from these ^
plants or other sources will be needed to provide for the attainment of the tf|
standards. Further, more vigorous enforcement of currently adopted
regulations for controlling open burning and incinerators must be under- ^1
taken by the appropriate air pollution control agency. Alternatively,
other equivalent improvements in the particulate control strategy may be
employed, as determined by the State and approved by EPA.
Because of this identified deficiency, the Regional Administrator
finds that a revision to parts of the control strategy for participate
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matter in the applicable plan is needed. This Federal Register Notice
is intended to officially advise the (State) of this requirement.
Accordingly, the State shall prepare and submit, by July 1, 1977, a
plan revision containing adopted emission limiting regulations, as
needed, which it is reasonable to anticipate will be achievable within
a reasonable period of time to provide for the attainment and mainten-
ance of the national primary particulate matter standards. If additional
control measures (e.g., land use and transportation measures) are
needed, such measures may be submitted no later than July, 1978. The
plan revision should identify the nature and sources of emissions
within the Southeast portion of Smogtown and demonstrate how the adopted
regulations will provide for the attainment and maintenance of the
national standards. The plan should include a demonstration that
emission increases that will result from projected growth of population,
industrial activity, etc., will not cause the national standard to be
violated. Compliance schedules for any source affected by any new or
revised regulation must be submitted in accordance with the requirements
of 40 CFR 51.15 (Compliance Schedules). The plan revision should also
indicate any additional resources needed to implement the control plan
beyond those already provided for in the plan, along with the State's
commitment to provide additional manpower and money to implement the con-
trol measures. If responsibility for implementing any portion of the
plan revision is delegated to other State and/or local agencies, a
description of the specific responsibility of each agency in implementing
the plan shall be submitted. The plan revision shall be submitted by
the State in accordance with the provisions of Section 51.4, Public
Hearings, and Section 51.5, Submission of Plans and otherwise fulfill •
I
the requirements of Part 51.
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The State is advised that the plan revision must provide for the
attainment of primary standards as expeditiously as practicable. It is •
the judgment of the Regional Administrator that adequate time exists
for the State to revise the plan so as to provide for attainment of |
primary standards by mid-1977 as provided under the Clean Air Act. •
If the plan revision requires substantially more restrictive emission
controls than are presently included in the approved plan, and if •
the requirements of 40 CFR 51.30 are met, then an extension to mid-
1977 can be approved by the Agency for the attainment of national primary •
particulate matter standards. Such an extension should be formally
requested by the Governor when submitting the plan revision. The State f
is further advised that additional time can be provided for the attain- ^
ment of secondary standards, so long as such standards are attained within ^
a "reasonable time". The revised plan shall indicate the date the A
national standards will be attained.
The Governor shall submit, within 60 days, a letter of intent to H
the Regional Administrator, EPA, Region III which identifies the various
action steps (along with target dates for completion) which the State ^P
will take to develop the plan revision in accordance with the require- ^
ments set forth in this notice. The S, \te muit also identify the agencies ^^
that have been given responsibility to prepare the plan revision. Failure |M
by the State to submit a letter of intent within the allotted 60 days
will be considered by EPA as an indication that no plan revision will be •
forthcoming from the State. In this case, EPA will begin to develop for
promulgation a federal plan to attain and maintain national standards.
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All of the applicable plan remains in effect until the plan revision
is submitted by the State to EPA and is approved by EPA or until EPA
promulgates substitute (or additional) regulations.
This notice is not subject to rulemaking procedures. The need for a plan
revision is based upon a technical finding of the Regional Administrator
which clearly shows that the control strategy for particulate matter in
the Metropolitan Smogtown Intrastate Region is inadequate and needs to be
revised. Authority for such action is provided in Sections 110(a)(2)(H)
and 110(c) of the Clean Air Act, 1970. Ample opportunity for public comment
on the Regional Administrator's determination will be provided. If the
State develops its own revisions and submits them to EPA, public hearings
will be required at the State level and EPA will provide opportunity for
written comments prior to taking action on the submission; if EPA must
propose and promulgate its own regulations, EPA will provide opportunity
for written comments and, if the State held no hearing on the revisions,
will provide opportunity for a public hearing. Authority: Section
110(a)(2)(H) of the Clean Air Act, as amended, 42 U.S.C. 1857c-5(a)(2)(H)
and Section 110(c) of the Clean Air Act, as amended, 42 U.S.C. 1857c-5(c).
Date
Regional Administrator
Environmental Protection Agency
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APPENDIX B. GUIDELINES ON AMBIENT TREND MONITORING
1. General Guidelines for Regional Office Monitoring Programs 1.2-007
• PURPOSE: General summary of existing ambient trend moni-
toring guidelines
| 2. Guidelines for Interpretation of Air Quality Standards 1.2-008*
•| PURPOSE: Answer questions on how NAAQS and air quality is
related
• 3. Guidelines for Network Design and Instrument Siting 1.2-012*
PURPOSE: Network design and instrument siting criteria
fj 4. Procedures for Flow and Auditing of Air Quality Data 1.2-013*
^ PURPOSE: Steps to insure valid data
^ 5. Guidelines for Evaluation of Air Quality Trends 1.2-014*
ft PURPOSE: Trend evaluation
6. Guidelines for the Evaluation of Air Quality Data 1.2-015*
^1 PURPOSE: Evaluation methodology
«7. A Description of Analytical Techniques and Associated SAROAD 1.2-017
Method Codes Used in Storing Data in NADB
^ PURPOSE: Decoding of method codes used in NADB
8. Designation of Criteria Pollution Analytical Methods as 1.2-018*
II Acceptable/Not Acceptable for Purposes of Data Analysis
PURPOSE: Acceptability of data and instruments
9. Air Quality Monitoring Site Description Guidelines 1.2-019*
PURPOSE: Information on Monitoring Sites
*Also included in Volumn 11, Air Quality Maintenance Guidelines
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APPENDIX C
ENVIRONMENTAL
PROTECTION TRANSMITTAL
AGENCY
Addressee
1270.5
October 15, 1973
DELEGATIONS OF AUTHORITY - AIR AND WATER PROGRAMS
MATERIAL TRANSMITTED:
EPA Order No. 1270.5 - Delegation of Authority to Request States to
Revise State Implementation Plans.
MATERIAL SUPERSEDED:
None.
\
FILING INSTRUCTIONS:
^* File the attached material in numerical order in a three-ring binder
^. established for the EPA Directives System.
Howard M. Messner
Deputy Assistant Administrator
for Administration
Dist: Directives Distribution
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ENVIRONMENTAL I
PROTECTION ORDER 1270.5 I
AGENCY I J -
October 15, 1973 •
DELEGATIONS OF AUTHORITY - AIR AND WATER PROGRAMS
DELEGATION OF AUTHORITY TO RECJUEST STATES TO
REVISE STATE IMl'LEMENTATION PLANS
1. PURPOSE. This Order delegates to the Regional Administrators the
authority to request States to revise State Implementation Plans under
Section 110(a)(2)(H) (ii) of the Clean Air Act.
2. BACKGROUND. Section 110 (a) (2) (H) (ii) of the Clean Air Act provides ••
for the revision of State Implementation Plans (SIP's) "whenever the
Administrator finds on the basis of information available to him that the
plan is substantially inadequate to achieve the national ambient nir
quality primary or secondary standard which it implements." In view of
the emphasis on utilizing regional offices in supervising t lie SIP's, a
delegation of authority to the Regional Administrators to request the
revisions is in order.
3. DELEGATION. The Regional Administrators are delegated auttiority to
perform the responsibilities indicated above within their respective
regions.
4. LIMITATIONS.
a. Revisions will be requested only when such revisions are clearly
necessary.
b. Where the requested revision would affect emission control
regulations significantly, or the enforcement thereof, Regional Admin-
istrators should obtain the concurrence of the Assistant Administrator
for Air and Water Programs and the Assistant Administrator for Enforce-
ment and General Counsel.
c. Where the requested revision would have significant national
policy implications or would establish a significant precedent, the
concurrence of the aforesaid Assistant Administrators is required.
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Dist: Directives Distribution Initiated by: AF
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ORD£R
1270.5
October 15, 1973
d. Insofar as other revisions are concerned, Regional Administrators
should simply notify the two Assistant Administrators of requests made.
e. This authority may not be redele
RU(;seD.l El. Train
Administrator
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Eavi»e«a«it*l Protection
Segiott V, Library
2*3 South Oe*rfeorn Street
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2 or 3 percent of the one-hour standard and about 10 percent
of the eight-hour standard.
It is recommended that street canyon sensor inlets be
located near mid-block, at least 10 m from the intersection. The
choice of mid-block locations over intersection locations was
made because intersections represent a much smaller portion of
downtown space than do the street between them. The pedestrian
exposure times are probably also greater in street canyons than
at intersections. Finally, the practical difficulties of posi-
tioning inlets are less at mid-block locations than at an inter-
section.
B. Neighborhood
The inlet heights for neighborhood monitoring stations
are specified to be between 2.5 and 3.5 m. The rationale is to
obtain measurements that are consistent with street canyon type
measurements and are taken as near as practical to average breath-
ing heights. As in the case with street canyon monitors, we would
like to minimize the differences from the 3 meter elevation. If,
however, the 3 + % meter inlet height criteria is physically
impractical, more flexibility maybe allowed since the expected
gradient with height is less (5%/m)than in the street canyon
situation (.5 ppm/m). However, actual measured vertical gradients
at the specific location should be determined so that the effect
of deviation from the standardized criteria could be documented
and taken into account.
The presumption has been, in determining minimum separa-
tion between a monitoring site and a specific source, that the
neighborhood or regional measurements should not be unduly influ-
enced by any single source. A subjective judgment is required as
to what constitutes undue influence. There are at least two bases
for making that judgment. A maximum concentration value can be
assigned and the separation between the monitoring site and all
sources should be such that the contribution from any one source
does not exceed the assigned maximum. The other approach is to
examine the disturbance in the concentration gradients caused by
sources and assign a maximum allowable gradient from any given
source. Both approaches were tried and are fully documented in
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