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                                 DRAFT copy


          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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                           SUPPLEMENT A

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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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                              -3-

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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                              -7-

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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                                  -8-
                                                    MEAN
                                                    WIND ,
                                                     (u)
                                                          BACKGROUND
                                                        CO CONCENTRATION
                                                             (Cb)
                                  TRAFFIC
                                    LANE
                               -W-
Figure  1-6. Schematic of cross-street circulation in street canyon

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                                -9-
             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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                                -10-
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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                               -11-
      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.
                                1-2

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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

                                1-3

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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
                                1-4

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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
                                1-6

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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.
                                1-7

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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.
                                 1-8

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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.
                                 1-11

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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
                              II-1

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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.
                               II-2

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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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II-4

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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
                           II-5

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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.
                          II-6

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II-7

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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.
                                                    II-9

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11-10

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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.
                               11-11

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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
                              11-12

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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
                               11-13

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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
                                11-14

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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
                               11-15

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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.
                           11-16

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                                                          CM
                                                           E
                                                           Q.
                                                          8
                                                          
                                 11-17
                                                                                      60
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                                                                    CO
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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
                                   11-18

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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.
                                 11-19

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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



                                  11-20

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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


                               11-21

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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
                                11-22

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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.
                               11-23

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                       11-24
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                                                          BACKGROUND
                                                        CO CONCENTRATION
                               PRIMARY     RECEPTOR
                               VORTEX
                                   TRAFFIC
                                    LANE
                               -W-
Figure II-6.   Schematic of cross-street  circulation in street  canyon'
                                 11-25

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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.
                               11-26

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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.
                                1-2

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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

                                1-3

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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
                                1-4

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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
                                 1-5

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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
                                1-6

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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.
                                1-7

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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.
                                 1-8

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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.
                                 1-11

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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
                              II-1

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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.
                               II-2

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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
                           II-5

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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.
                          II-6

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II-7

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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.
                                                    II-9

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                                                   c
                                                  s
                                                   60
                                                   C
                                                   C
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11-10

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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.
                               11-11

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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
                              11-12

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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
                               11-13

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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
                                11-14

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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
                               11-15

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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.
                           11-16

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                                                          CM
                                                           E
                                                           Q.
                                                          8
                                                          
                                 11-17
                                                                                      60
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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
                                   11-18

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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.
                                 11-19

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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



                                  11-20

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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


                               11-21

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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
                                11-22

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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.
                               11-23

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                       11-24
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                                                          BACKGROUND
                                                        CO CONCENTRATION
                               PRIMARY     RECEPTOR
                               VORTEX
                                   TRAFFIC
                                    LANE
                               -W-
Figure II-6.   Schematic of cross-street  circulation in street  canyon'
                                 11-25

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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.
                               11-26

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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.
                               II-26B

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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
                         11-27

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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.
                                   11-28

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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
                            11-29

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O    »-       CM CO
                                                          0
                                                          O
                                                         •H
                                                         4-1
                                                          O
                                                          0)
                                                          to
                                                         •H
                                                         tfl
                                                         01
                                                         C
                                                         M
                                                         •H
                                                         0)
                                                         0)
                                                         0)
                                                         C3

                                                         CO  M
                                                         C  d)
                                                             W)
                                                         c H
                                                         K*  d)
                                                         O  M
                                                         N  3
                                                         •ft  CD
                                                         t-i  cd
                                                         O  01
                                                         "  E
                                                        00
                                                         I
                                                         60
                                                        •H
     11-30

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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
                              11-31

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8
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CM CM CM CM
A A A A







CM CM CM
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m in m m
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C 13 4-1 O CO 01
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rx-ri o 9 oic MJ
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§3 w O -f-1 0) co co
>w in a, E -u xi co
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01 U CO OI
PL, z n CM
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CM CM CM CM CM CM
A A A A A A







CM CM CM CM
i I O O O O
U JJ 4J 4J


in m in m in in

o o o o o o
4J 4J . *l 4J *J 4J
CM CM CO CO CO CO


Q
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a) .-.; 1-1 •> «
x; eg M r-i o
TJ oi a c
^^ C! 4-1 ^4 ^
t» M *J u
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co -o a TJ
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0 M X d 01
TJ  01 CO O)
S5 w p4 !5 PQ 114





B i
cu ,
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CM C<4
A A







CM CM
o o
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m m

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i g
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a
a
pi
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pi
9


                                  11-32

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C*"^
5
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A A A A A A









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r-4 r-*


CM CM CM O Irt VQ
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CO CO CO CO CO CO


I o " y
•*-< C g E
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g.g.g.g.ggg g tt s «
to co w to m JK if CT m nj w
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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
                          11-34

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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


                                11-35

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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.


                               11-36

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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
                                11-37

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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.
                               11-38

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>;-XWB-lK'.'i.:7,v:.J'S'rvMW.'.15>ll1!B-ll-^7f ' "
i$&S ^MS&$&&^1
o fc a !
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 '
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:n = ac I
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uj o 3: ;
>  CI> U"> C3 \J
» oo r-~ r^. u
£Ui/3rf 'NOIiVMiN30NOO dSl
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4-1
'•JO f^CJN
ro ai x— v
YEAR
ual primary standard for '.
etric deviation equals 1.6
oc co
ii i cO 0)
O- a)
ro t/» J3 TJ
*~"1  21
U. ^ g
O -H CO
to
a: a; ^
S « « 8
S: ai 01
UK T3 -H
^3 -HO
•jp ii._i ci
Z C OJ
O 3
o cr
•— • 01
9. Ninety-five percen
various sampling f
K
Oi
3
60
•H
11-39

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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
                                11-40

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be to have a continuous Instrument adjusted to measure the peak levels,

and a bubbler for long term population exposure.
                               11-41

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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
I
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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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                                                                             I
     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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                                                                             I
 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.
'                                        11
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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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 I
          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.
                                                                            I

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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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                                                                             I
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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                                                                              I
    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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  I

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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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                                                                            I
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
I
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                                                                            I
opies to rpDronriete review  r-ffices.
                                                                           _
                                                                           ™
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
                                                                             I
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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
1
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.
29

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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
•
1 1
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1 '
!•
1
•
I
1
1
1
1
1
1

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                                                                     I
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          GUIDELINE  SERIES
                     OAQPS NO.
                  1.2-011
t



t



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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
^u

™

              «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.
                                                                                   I
                                                                                   I
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            —
                                                                                   V
                                                                                   §
      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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                                                                                   I
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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 I
 •              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

   M


             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
                                                                                     m
 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.
                            8
§

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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
                                                                                      m
        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.
                                   10
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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.
                                           11

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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
                                                                                      m
substantially  inadequate  provides the Regional Office with flexibility                JH
in assessing the need for, and especially the timing of a call for plan
revision.

                                12
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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
                                                 13

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                                                                                   I
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.
                                14

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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?



                                  15

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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
                               16
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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.



                               17

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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?
18

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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?
                                              19

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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.
                                                                                    I
                                                                                    I
     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.


                                             21

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                                                                                 I
     (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                '"
                                                                                 I
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.
                              22

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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
                                             23

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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.
                                                                 I
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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
                                                                      1
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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,
                                               25

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                                                                                      I
             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:
I
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





                                 26
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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).
                                28
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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

                                              29

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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)



                                      30
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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




                                           31

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                                                                                   I
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
                              32
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                                                                                    ™

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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.
                                                 33

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                                                    I
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.
                                            35

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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.
                                                                37

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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

                                  A-2

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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.
                               A-3

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                                                                                      I
     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.
                                 A-4

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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
                                              A-5

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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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                                   C-2
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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                                         C-3
                                          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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           PAR 4
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Eavi»e«a«it*l Protection
Segiott V, Library
2*3 South Oe*rfeorn Street

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                              -12-
 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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