United States
            Environmental Protection
            Agency
            Office of Air Quality
            Planning and Standards
            Research Triangle Park NC 27711
EPA-450/4-87-007
May 1987
            Air
vvEPA
Ambient Monitoring
Guidelines for
Prevention of
Significant
Deterioration (PSD)

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                                        •RA-450/4-87-007
                                        ../lay 1987
Ambient Monitoring Guidelines
  for Prevention of Significant
         Deterioration (PSD)       \
                       by

            Monitoring and Data Analysis Division
          Office of Air Quality Planning and Standards

                       and

         Environmental Monitoring Systems Laboratory
             Office of Research and Development
            U.S. Environmental Protection Agency
             Research Triangle Park NC 27711
              U.S. Environment?! Protection Agency
              Rpoio.i :J U'C'-ary (?{ I- ;>
              77°VV?/;; '-•-'.'• >• ^'•."'•^'>, 12th Floor
              Chicago, iL  b(;u04-J-'JO

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                                  FOREWORD
     Many individuals were involved in the preparation of this document

and should be contacted if any questions arise in the application of the

guideline.
   Subject Area

Ambient Air Quality
 Monitoring

Meteorological
 Monitoring

Quality Assurance
 (Ambient Air
  Quality)

PSD Policy and
 Interpretation
 of Regulations

Acceptable Methods
 Non-Criteria
 Pollutants
 Contact

Stan Sleva
David Lutz

James Dicke
Larry Purdue
Jack Puzak
Gary McCutchen
Larry Purdue
Ken Rehme
 Phone Number
(Area Code 919)

    541-5652
    541-5476

    541-5682
    541-2665
    541-2106
    541-5592
    541-2665
    541-2666
FTS Number

 629-5652
 629-5476

 629-5682
 629-2665
 629-2106
 629-5592
 629-2665
 629-2666

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                                 DISCLAIMER





     This report has been prepared by the Office of Air Quality Planning



and Standards and the Environmental Monitoring Systems Laboratory, U.S.



Environmental Protection Agency, and approved for publication.   It has been



subject to the Agency's peer and administrative review, and it  has been



approved for publication as an EPA document.



     Mention of trade names or commercial products does not constitute



endorsement or recommendation for use.
                                    111

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                                TABLE OF CONTENTS


                                                                        Page

1.  INTRODUCTION [[[    1

2.  GENERAL REQUIREMENTS AND CONSIDERATIONS ...........................    3

    2.1  Monitoring Data Rationale ------------------------------------    3

         2.1.1  Criteria Pollutants - Preconstruction Phase -----------    3
         2.1.2  Criteria Pollutants - Postconstruction Phase ----------    4
         2.1.3  Noncriteria Pollutants - Preconstruction and
                Postconstruction Phase --------------------------------    5

    2.2  Monitoring Objective and Data Uses ---------------------------    5

    2.3  VOC and 03 Monitoring Requirements ---------------------------    5

    2.4  Use of Representative Air Quality Data -----------------------    6

         2.4.1  Monitor Location --------------------------------------    6
         2.4.2  Data Quality ---------- ...... --------------------------    8
         2.4.3  Currentness of Data ------------------------------ .....    9
         2.4.4  Provisions for PMio and TSP in Transition Period
                of 1987 PSD Amendments --------------------------------    9

    2.5  Duration of Monitoring ---------------------------------------    9

         2.5.1  Normal Conditions -------------------------------------    9
         2.5.2  Transition Period for PMo and TSP --------------------   10
                2.5.2.1 Transition Within 10 Months After
                        Effective Date of PMiQ Amendments -------------   10
                2.5.2.2 Transition During 10-16 Months After
                        Effective Date of PMio Amendments -------------   11
                2.5.2.3 Transition During 16-24 Months After
                        Effective Date of PMiQ Amendments -------------   12
                2.5.2.4 Period Following 24 Months After Effective
                        Date of PM   Amendments -----------------------   12
    2.6  Sampling Methods and Procedures ------------------------------   13

    2.7  Frequency of Sampling ----------------------------------------   13

    2.8  Monitoring Plan ----------------------------------------------   14


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                          TABLE OF CONTENTS (Continued)


                                                                        Page

3.  NETWORK DESIGN AND PROBE SITING CRITERIA ........................ —   17

    3.1  Network Design -----------------------------------------------   17

    3.2  Number and Location of Monitors ------------------------------   17

         3.2.1  Preconstruction Phase ---------------------------------   17
         3.2.2  Postconstruction Phase --------------------------------   19
         3.2.3  Special Concerns for Location of Monitors -------------   19

    3.3  Probe Siting Criteria -----------------------------------------  19

         3.3.1  Total Suspended Particulates (TSP) ........... - ...... ---  21

                3.3.1.1  Vertical Placement ............................  21
                3.3.1.2  Spacing from Obstructions ------- ...... --------  22
                3.3.1.3  Spacing from Roads --------------- .......... —  22
                3.3.1.4  Other Considerations --------------------------  24

         3.3.2  PMo ......................................... - .........  24
                3.3.2.1  Vertical Placement -------------------- ..... —  24
                3.3.2.2  Spacing from Obstructions ---------------------  24
                3.3.2.3  Spacing from Roads ----------------------------  25
                3.3.2.4  Other Considerations --------------------------  25

         3.3.3  Sulfur Dioxide (S02) ...................................  25

                3.3.3.1  Horizontal and Vertical Probe Placement -------  25
                3.3.3.2  Spacing from Obstructions ---------------------  25

         3.3.4  Carbon Monoxide  (CO)— ..... - ...........................  26

                3.3.4.1  Horizontal and Vertical Probe Placement -------  26
                3.3.4.2  Spacing from Obstructions ---------------------  26
                3.3.4.3  Spacing from Roads ----------------------------  26

         3.3.5  Ozone (03) ------ ........... - ......... - .............. —  27

                3.3.5.1  Vertical and Horizontal Probe Placement -------  27
                3.3.5.2  Spacing from Obstructions ---------------------  27
                3.3.5.3  Spacing from Roads ----------------------------  27

         3.3.6  Nitrogen Dioxide (N0£) ..... - ........................ —  28

                3.3.6.1  Vertical and Horizontal Probe Placement -------  28
                3.3.6.2  Spacing from Obstructions ---------------------  28

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                          TABLE OF CONTENTS (Continued)


                                                                        Page

         3.3.7  Lead (Pb)	  28

                3.3.7.1  Vertical Placement	  28
                3.3.7.2  Spacing from Obstructions	  29
                3.3.7.3  Spacing from Roads	  29
                3.3.7.4  Other Considerations	  29

         3.3.8  Noncriteria Pollutants		  29

                3.3.8.1  Vertical Placement	—-  29
                3.3.8.2  Spacing from Obstructions	  30
                3.3.8.3  Other Considerations	-	-  30

    3.4  Probe Material and Pollutant Sample Residence Time	  30

    3.5  Summary of Probe Siting Requirements	  31

4.  QUALITY ASSURANCE FOR AIR QUALITY DATA	  38

    4.1  Quality Assurance for Criteria Air Pollutants	  38

         4.1.1  General Information	  38

         4.1.2  Quality Control Requirements	  39

                4.1.2.1  Organizational Requirements	  39
                4.1.2.2  Primary Guidance	  39
                4.1.2.3  Pollutant Standards		-	  40
                4.1.2.4  Performance and System Audit Programs	  40

         4.1.3  Data Quality Assessment Requirements	  40

                4.1.3.1  Precision of Automated Methods	  40
                4.1.3.2  Accuracy of Automated Methods	  41
                4.1.3.3  Precision of Manual Methods	  42
                4.1.3.4  Accuracy of Manual Methods	  42

         4.1.4  Calculations for Automated Methods	  43

                4.1.4.1  Single Analyzer Precision	  43
                4.1.4.2  Single Analyzer Accuracy	  44

         4.1.5  Calculations for Manual Methods	  45

                4.1.5.1  Single Instrument Precision for TSP, Pb,
                         and PMio	-	  45
                4.1.5.2  Single Instrument Accuracy for TSP and PMiQ—  45
                4.1.5.3  Single Instrument Sampling Accuracy for Pb	  45
                4.1.5.4  Single-Analysis-Day Accuracy for Pb	  45

                                        vi

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                          TABLE OF CONTENTS (Continued)


                                                                        Page

         4.1.6  Organization Reporting Requirements	  46

    4.2  Quality Assurance for Noncriteria Air Pollutants	  46

         4.2.1  Selection of Method			  46
         4.2.2  Calibration	  46
         4.2.3  Data Validation		-	  47
         4.2.4  Standard and Split Samples			  47

5.  METEOROLOGICAL MONITORING	  48

    5.1  Data Required		—  48

    5.2  Exposure of Meteorological Instruments	  49

6.  METEOROLOGICAL INSTRUMENTATION	  52

    6.1  Specifications	  52

         6.1.1  Wind Systems (horizontal wind)	  52
         6.1.2  Wind Systems (vertical wind)	  52
         6.1.3  Wind Fluctuations	  52
         6.1.4  Vertical Temperature Difference	  53
         6.1.5  Temperature	  53
         6.1.6  Humidity	  53
         6.1.7  Radiation - Solar and Terrestrial	  53
         6.1.8  Mixing Height	  53
         6.1.9  Precipitation	  54
         6.1.10 Visibility	  54

7.  QUALITY ASSURANCE FOR METEOROLOGICAL DATA		  55

8.  DATA REPORTING	  56

    8.1  Air Quality Data Reporting	  56
    8.2  Meteorological Data Format and Reporting	  56

APPENDIX A - PROCEDURES TO DETERMINE  IF MONITORING DATA WILL BE
             REQUIRED FOR A PSD APPLICATION

1.  INTRODUCTION	A-l

2.  PSD PERMIT APPLICATION PROCEDURES	A-l
    2.1  Part 1 - Source Applicability  Determination	A-l
    2.2  Part 2 - Pollutant Applicability Determination—	A-3
    2.3  Part 3 - BACT Analysis	A-5
    2.4  Part 4 - Ambient Air  Quality Analysis	A-5
    2.5  Part 5 - Source Impact Analysis	A-7
                                       vn

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                          TABLE OF CONTENTS (Continued)
                                                                        Page
    2.6  Part 6 - Additional  Impact Analysis	A-7
    2.7  Part 7 - File Complete PSD Application	A-7

3.  DECISIONS FOR MONITORING DATA REQUIREMENTS	A-10

REFERENCES	 A-24
                                       vm

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                               1.  INTRODUCTION
     The Clean Air Act Amendments of 1977, Part D, Prevention of Significant
Deterioration, require that certain new major stationary sources and major
modifications be subject to a preconstruction review which includes an
ambient air quality analysis. Furthermore, the Act requires that an analysis
be conducted in accordance with regulations promulgated by the EPA.  In
this regard, the Agency promulgated PSD regulations [1] on June 19, 1978,
which included ambient monitoring requirements.  Guidelines were published
in May 1978 [2] to discuss monitoring for PSD purposes.  However, in response
to the June 18, 1979 preliminary Court Decision (Alabama Power Company v._
Costle, 13 ERC 1225), EPA proposed revised PSD regulations L3J on September
5, 1979.  The final court decision was rendered December 14, 1979 [4],
Based on the public comments to the September 5, 1979 proposed PSD regulations
and the December 14, 1979 court decision, EPA promulgated new PSD regula-
tions on August 7, 1980.  Some of the pertinent provisions of the 1980 PSD
regulations that affect PSD monitoring are discussed below:

     (a)  Potential to emit.

          The PSD regulations retain the requirement that new major
          stationary sources would be subject to a new source review on
          the basis of potential to emit.  However, the_..axinuaj[emission
          potential of a source will be determined after the application
          of air pollution controls rather than before controls as was
          generally done under the 1978 regulations [1].

     (b)  De minimis cutoffs.

          The PSD regulations will exempt on a pollutant specific basis
          major modifications and new major stationary sources from all
          monitoring requirements when emissions of a particular pollutant
          are below a specific significant emission rate, unless the
          source is near a Class I area.  Also included are significant
          air quality levels which may be used to exempt sources or
          modifications from PSD monitoring when the air quality impacts
          from the sources or modifications are below specified values.

     (c)  Noncriteria pollutants.

          The 1978 PSD regulations [1] required monitoring only for those
          pollutants for which national ambient air quality standards
          exist. However, there are a number of pollutants for which
          no ambient standards exist (noncriteria pollutants) but which
          are regulated under new source performance standards and
          national emission standards for hazardous pollutants.  The
          1980 regulations [5J require an ambient air quality analysis
          for all regulated pollutants emitted in significant amounts.
          This analysis will generally be based on modeling the impact
          of the pollutants in lieu of collecting monitoring data.

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     (d)   Reconstruction  monitoring.

          A list of air quality  concentrations  is  included  in  the  PSD
          regulations  as criteria  for  generally exempting proposed sources
          or modifications from  collecting  monitoring  data.   Basically,
          monitoring data  will be  required  if the  existing  air quality
          and the impact of the  proposed  source or modification is equal
          to or greater than these concentrations.  In certain cases,
          even though  the  air quality  impact or background  air quality
          may be less  than these concentrations, monitoring  data may be
          required if  the  proposed source or modification will  impact a
          Class I area, nonattainment  area, or  area where the  PSD  incre-
          ment is violated.

     (e)   Postconstruction monitoring.

          The PSD regulations include  authority to require  postconstruc-
          tion monitoring.  In general,  EPA may require postconstruction
          monitoring from  large  sources  or  sources whose impacts will
          threaten standards or  PSD increments. The permit  granting
          authority will make this decision on  a case-by-case  basis.

     In 1987 [6] EPA promulgated revisions  to the  National  Ambient Air
Quality Standards (NAAQS)  for Particulate Matter.   Also, revisions were
promulgated to revise  the  PSD regulations to account for the NAAQS changes.
The PM^g amendments will not require any new data  gathering requirements  be-
yond the 1980 PSD requirements for PSD applications submitted  not  later than
10 months after the effective date of  the 1987  PSD amendments.  New monitoring
requirements for PMjo  will be phased in  for PSD applications submitted greater
than 10 and and less than  24 months after the effective date of the 1987  PSD
amendments.  In addition,  all new  monitoring requirements  for  PM^g will be  in
effect 24 months after the effective date of the PSD amendments.

     Because of the revisions to the PSD regulations,  this  guideline has  been
modified to reflect such revisions.  The purpose of this guideline is to
address those items or activities  which  are considered essential in conducting
an ambient air quality monitoring  program.   Guidance is given  for  designing  a
PSD air quality monitoring network as  well  as the  operational  details such  as
sampling procedures and methods, duration of sampling, quality assurance
procedures, etc.  Guidance is also given for a  meteorological  monitoring
program as well as the specifications  for meteorological instrumentation  and
quality assurance procedures.

     An appendix is included to show how the  ambient air quality analysis
fits in the overall PSD requirements.   Flow diagrams are presented to  aid a
proposed source or modification  in assessing  if monitoring  data may be
required.

     General adherence to the guidance contained in this document  should
ensure consistency in  implementing the PSD  monitoring regulations.

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                 2.  GENERAL REQUIREMENTS AND  CONSIDERATIONS


2.1  Monitoring Data Rationale

     The court decision [4] has affirmed the Congressional  intent  in  the
Clean Air Act as it relates to PSD monitoring  requirements.   The court
ruled that section 165(e)(l) of the Clean Air  Act requires  that  an air
quality analysis be conducted for each pollutant  subject  to  regulation
under the Act before a major stationary source or major modification  could
construct.  This analysis may be accomplished  by  the use  of modeling  and/or
monitoring the air quality.  EPA has discretion in specifying the  choice of
either monitoring or modeling, consistent with the provisions in section
165(e)(2).  As will be discussed later, modeling  will  be  used in most cases
for the analysis for the noncriteria pollutants.

     The court ruled that section 165(e)(2)  of the Clean  Air  Act requires
that continuous preconstruction air quality  monitoring data must be collected
to determine whether emissions from a source will result  in exceeding the
National Ambient Air Quality Standards (NAAQS).  Further, the data could be
used to verify the accuracy of the modeling  estimates  since modeling  will
be the principal mechanism to determine whether emissions from the proposed
source or modification will result in exceeding allowable increments.  In
regard to monitoring requirements, the court stated that  EPA  had the  authority
to exempt de mini mis situations.

     Postconstruction monitoring data requirements are addressed in section
165(a)(7) of the Clean Air Act.  Sources may have to conduct  such  monitoring
to determine the air quality effect its emissions may have  on the  area  it
impacts. EPA has the discretion of requiring monitoring data  and the  court
stated that guidelines could be prepared to  show  the circumstances that may
require postconstruction monitoring data.

     In view of the provisions of sections 165(e)(l),  165(e)(2), and  165(a)(7)
of the Clean Air Act, the de mini mis concept,  and sections  of the  final  PSD
regulations, Sections 2.1.T7 2.1.2 and 2.1.3 present the  basic rationale
which generally will be followed to determine  when monitoring data will  or
will not be required.  It should be noted that the subsequent use  of  "moni-
toring data" refers to either the use of existing representative air  quality
data or monitoring the existing air quality.

     Additional discussion and flow diagrams are  presented  in Appendix  A of
this guideline which show various decision points leading to  a determination
as to when monitoring data will or will not  be required.  Also,  these
procedures indicate at what points a modeling  analysis must  be performed.

2.1.1  Criteria Pollutants - Preconstruction Phase

     For the criteria pollutants (S02, CO, and N02) continuous air quality
monitoring data must, in general, be used to establish existing  air quality

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concentrations in the vicinity of the proposed source or modification.   For
VOC emissions, continuous ozone monitoring data must be used to establish
existing air quality concentrations in the vicinity of the proposed source
or modification.  For PMjQ and lead, the 24-hour manual  method will  be  used
to establish the existing air quality concentrations.  However, no pre-
construction monitoring data will  generally be required if the ambient
air quality concentration before construction is less than the significant
monitoring concentrations.  (The significant monitoring concentrations  for
each pollutant are shown in Table A-2 in the appendix to this guideline.)
To require monitoring data where the air quality concentration of a pollutant
is less than these values would be questionable because these low level
concentrations cannot reasonably be determined because of measurement
errors.  These measurement errors may consist of errors in sample collection,
analytical measurement, calibration, and interferences.

     Cases where the projected impact of the source or modification is  less
than the significant monitoring concentrations would also generally be
exempt from preconstruction monitoring data, consistent with the de mini mis
concept.  [40 CFR 51.24(1)(8) and 40 CFR 52.21(i)(8)].

     The one exception to the de mini mis exemption occurs when a proposed
source or modification would adversely impact on a Class I area or would
pose a threat to the remaining allowable increment or NAAQS.  For those
situations where the air quality concentration before construction is near
the significant monitoring concentration, and there are uncertainties
associated with this air quality situation, then preconstruction air quality
monitoring data may be required.  These situations must be evaluated on a
case-by-case basis by the permit granting authority before a final decision
is made.

2.1.2  Criteria Pollutants - Postconstruction Phase

     EPA has discretion in requiring postconstruction monitoring data
under section 165(a)(7) of the Clean Air Act and in general will not
require postconstruction monitoring data.  However, to require air
quality monitoring data implies that the permit granting authority will
have valid reasons for the data and, in fact, will use the data after it
is collected.  Generally, this will be applied to large sources or
sources whose impact will threaten the standards or PSD increments.
Examples of when a permit granting authority may require postconstruction
monitoring data may include:

     a.   NAAQS are threatened - The postconstruction air quality is
projected to be so close to the NAAQS that monitoring is needed to
certify attainment or to trigger appropriate SIP related actions if
nonattainment results.

     b.   Source impact is uncertain or unknown - Factors such as complex
terrain, fugitive emissions, and other uncertainties in source or emission
characteristics result in significant uncertainties about the projected

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impact of the source or modification.   Postconstruction  data is  justified
as a permit condition on the basis that model  refinement is  necessary to
assess the impact of future sources of a similar type and configuration.

2.1.3  Noncriteria Pollutants - Preconstruction  and Postconstruction  Phase

     Consistent with section 165(e)(l) of the  Clean Air  Act, EPA believes
that an analysis based on modeling of  the impact of noncriteria  pollutants
(including TSP) on the air quality should generally be used  in lieu of
monitoring data.  The permit granting  authority, however, does have the
discretion of requiring preconstruction and postconstruction monitoring
data.  Before a permit granting authority exercises its  discretion  in
requiring monitoring data, there should be an  acceptable measurement  method
approved by EPA (see Section 2.6)  and  the concentrations would generally  be
equal to or greater than the significant monitoring concentrations  (shown
in Table A-2 of the appendix).

     A permit granting authority may require monitoring  data in  cases such
as (a) where a State or other jurisdiction has a standard for a  noncriteria
pollutant and the emissions from the proposed  source or  modification  pose  a
threat to the standard, (b) where the  reliability of emission data  used as
input to modeling existing sources is  highly questionable, especially for
the pollutants regulated under the national emission standards for  hazardous
pollutants, and (c) where available models or  complex terrain make  it
difficult to estimate air quality or impact of the proposed  source  or
modification.

2.2  Monitoring Objective and Data Uses

     The basic objective of PSD monitoring is  to determine the effect
emissions from a source are having or  may have on the air quality in  any
area that may be affected by the emission.  Principal  uses of the data are
as follows:

     (a)  To establish background air  quality  concentrations in  the vicinity
of the proposed source or modification.  These background levels are  important
in determining whether the air quality before  or after construction are or
will be approaching or exceeding the NAAQS or  PSD increment.

     (b)  To validate and refine models.  The  data will  be helpful  in
verifying the accuracy of the modeling estimates.

2.3  VOC and 03 Monitoring Requirements

     The previous 0.24 ppm nonmethane  organic  compound (NMOC) standard,
which was used as a guide for developing State Implementation Plans to
attain the 63 ambient standard, has been rescinded.  However, VOC emissions
are the precursors in the formation of ozone.   Consequently, any new  source
or modified existing source located in an unclassified or attainment  area
for ozone that is equal to or greater  than 100 tons per  year of  VOC emissions
will be required to monitor ozone.  VOC monitoring will  not  be required.

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2.4  Use of Representative Air Quality Data


     The use of existing representative air quality data was  one of  the
options discussed in Section 2.1 for monitoring data.   In determining
whether the data are representative, three major items  which  need to be
considered are monitor location, quality of the data,  and currentness  of
the data.

2.4.1  Monitor Location

     The existing monitoring data should be representative of three  types
of areas:  (1) the location(s) of maximum concentration increase from  the
proposed source or modification, (2) the location(s) of the maximum  air
pollutant concentration from existing sources, and (3)  the location(s) of
the maximum impact area, i.e., where the maximum pollutant concentration
would hypothetically occur based on the combined effect of existing  sources
and the proposed new source or modification.   Basically, the locations and
size of the three types of areas are determined through the application of
air quality models.  The areas of maximum concentration or maximum combined
impact vary in size and are influenced by factors such  as the size and
relative distribution of ground level and elevated sources, the averaging
times of concern, and the distances between impact areas and  contributing
sources.

     In situations where there is no existing monitor in the  modeled areas,
monitors located outside these three types of areas may or may not be  used.
Each determination must be made on a case-by-case basis.  In  order to
clarify EPA's intent regarding the use of existing monitoring data,  some
examples are included to demonstrate the overall intent.

     (a)  Case I - If the proposed source or modification will be constructed
in an area that is generally free from the impact of other point sources
and area sources associated with human activities, then monitoring data
from a "regional" site may be used as representative data.  Such a site
could be out of the maximum impact area, but must be similar  in nature to
the impact area.  This site would be characteristic of air quality across  a
broad region including that in which the proposed source or modification is
located.  The intent of EPA is to limit the use of these "regional"  sites
to relatively remote areas, and not to use them in areas of multisource
emissions or areas of complex terrain.

     (b)  Case II - If the proposed construction will  be in an area  of
multisource emissions and basically flat terrain, then the proposed  source
or modification may propose the use of existing data at nearby monitoring
sites if either of the following criteria are met.

          1.  The existing monitor is within 10 km of the points of  proposed
emissions, or

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          2.  The existing monitor is  within  or not  farther than  1  km away
from either the area(s)  of the maximum air pollutant concentration  from
existing sources or the  area(s) of the combined maximum impact  from existing
and proposed sources.

          If the existing monitor(s) meets either of the above  two  conditions,
the data could be used together with the model  estimates to determine the
concentrations at all  three types of areas discussed earlier in this section.

     As an example of  the first criterion, if an existing monitor is located
within 10 km from the  points of proposed emissions but not within the
boundaries of the modeled areas of either of  the three locations  noted
above, the data could  be used together with model estimates to  determine the
concentrations at the  three types of required area.

     The next example  applies to the second criterion.  In evaluating the
adequacy of the location of existing monitors,  the applicant must first,
through modeling, determine the significant ambient  impact area of  the
proposed source.  In general, except for impact on Class I areas, the
application of air quality models for  the purpose of determining  significant
ambient impact would be  limited to 50  km downwind of the source or  to that
point where the concentration from the source falls  below the levels shown
in Table A-3 of the Appendix.  For Class I areas, a  significant impact is
1 ug/nr (24-hr) for PM10 and S02.  The applicant would then identify within
this significant impact  area the area(s) of the maximum air pollutant con-
centration from existing sources and the area(s) of  the combined  maximum
impact from existing and proposed sources. The area(s) of estimated maximum
concentration from existing sources or the estimated maximum combined
impact area(s) are determined as follows: First, within the modeled signifi-
cant ambient impact area, estimate the point  of maximum concentration from
existing sources, and  the point of combined maximum  impact (existing and
proposed source).  Using these concentration  values, determine  the  areas
enclosed by air quality  concentration  isopleths equal to or greater than
one half of the respective estimated maximum  concentration.  An existing
monitor located within or not farther  than 1  km away from of any  of these
areas can yield representative data.

     The rationale for considering the use of existing data collected from
monitors satisfying the  above criteria is that  modelers have a  reasonable
degree of confidence in  the modeling  results  within  the 10 km distance and
the maximum concentrations from most sources  are likely to occur  within
this distance.  Generally, the modeling results in this flat terrain case
may under or over predict by a factor  of two, and thus the actual maximum
impact from the source(s) could occur  at points where the model predicts
one half of this impact.  Data collected within or not farther  than 1 km
from areas may be considered as representative.

     (c)  Case III - If  the proposed construction will be in an area of
multisource emissions  and in areas of  complex terrain, aerodynamic  downwash
complications, or land/water interface situations, existing data  could only

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be used for PSD purposes if it were collected (1)  at the modeled location(s)
of the maximum air pollution concentration from existing sources, (2)  at
the location(s) of the maximum concentration increase from the proposed
construction, and (3) at the location(s)  of the maximum impact area.   If a
monitor is located at only one of the locations mentioned above and the
locations do not coincide, the source would have to monitor at the other
locations.

     It must be emphasized that the permit granting authority may choose
not to accept data proposed under the cases discussed above.  This may
occur because of additional factors, especially in Case II which were  not
discussed but must be considered, such as uncertainties in data bases  for
modeling and high estimates of existing air quality resulting in possible
threats to the applicable standards.  Because of such situations, the
permit granting authority must review each proposal on a case-by-case  basis
to determine if the use of existing data  will be acceptable.  It is important
for the proposed source or modification to meet with the permit granting
authority to discuss any proposed use of  existing data.  If the data are
not acceptable, then a monitoring program would have to be started to
collect the necessary data.

2.4.2  Data Quality

     The monitoring data should be of similar quality as would be obtained
if the applicant monitored according to the PSD requirements.  As a minimum,
this would mean:

     1.  The monitoring data were collected with continuous instrumentation.
         No bubbler data should be included.  See Section 2.7 for frequency
         of particulate pollutant sampling.

     2.  The applicant should be able to  produce records of the quality
         control performed during the time period at which the data were
         collected.  Such quality control records should include calibration,
         zero and span checks, and control checks.  In addition, quality
         control procedures should be a minimum specified in the instrument
         manufacturer's operation and instruction manual.

     3.  Historical data that were gathered from monitors which were operated
         in conformance with Appendix A or B of the Part 58 regulations [7]
         would satisfy the quality assurance requirements.

     4.  The calibration and span gases (for CO, S02 and N02) should be
         working standards certified by comparison to a National Bureau of
         Standards gaseous Standard Reference Material.

     5.  The data recovery should be 80 percent of the data possible during
         the information effort.

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2.4.3  Currentness of Data

     The air quality monitoring data should be current.   Generally, this
would mean for the preconstruction phase that the data must have been
collected in the 3-year period preceding the permit application, provided
the data are still representative of current conditions.   When such data
are required, the noncriteria pollutant data must also have been collected
in the 3-year period preceding the permit application provided that an
acceptable measurement method was used.  For the postconstruction phase,
the data must be collected after the source or modification becomes
operational .

2.4.4  Provisions for PMm and TSP in Transition Period  of 1987
       PSD Amendments

     Section 2.5.2 discusses the use of existing representative air quality
data for PIQ and TSP during the phasing in of the 1987 PSD amendments for
parti cul ate matter.  References are cited for using existing nonreference
and/or PM^ data where available, or TSP data.  Existing  representative air
quality data for PM^o collected more than 12 months after the effective date of
the 1987 PSD amendments must have been collected using reference or equivalent
     method samplers.
2.5  Duration of Monitoring

2.5.1  Normal Conditions

     If a source must monitor because representative air quality data are
not available for the preconstruction monitoring data requirement,  then
monitoring generally must be conducted for at least 1 year prior to submis-
sion of the application to construct.  Also,  if a source decides to monitor
because representative air quality data are not available for the postcon-
struction monitoring data requirement, then monitoring must also be conducted
for at least 1 year after the source or modification becomes operational.
However, under some circumstances, less than  1  year of air quality  data may
be acceptable for the preconstruction and postconstruction phases.   This
will vary according to the pollutant being studied.  For all pollutants,
less than a full year will be acceptable if the applicant demonstrates
through historical  data or dispersion modeling  that the data are obtained
during a time period when maximum air quality levels can be expected.
However, a minimum of 4 months of air quality data will  be required.  As
discussed in Section 2.1.3, monitoring for noncriteria pollutants will
generally not be required.

     Special attention needs to be given to the duration of monitoring for
ozone.  Ozone monitoring will  still  be required during the time  period when
maximum ozone concentrations will be expected.   Temperature is one  of the
factors that affect ozone concentrations, and the maximum ozone  concentrations
will generally occur during the warmest 4 months of the year, i.e., June-
September.  However, historical  monitoring data have shown that  the maximum

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yearly ozone concentration for some areas may not occur from June-September.
Therefore, ozone monitoring will  also be required for those months when
historical ozone data have shown  that the yearly maximum ozone concentrations
have occurred during months other than the warmest 4 months of the year.
This requirement is in addition to monitoring during the warmest 4 months
of the year.  If there is an interval of time between the warmest 4 months
of the year and month where historical monitoring data have shown that the
maximum yearly ozone concentration has occurred, then monitoring must also
be conducted during that interval.  For example, suppose historical data
have shown the maximum yearly ozone concentration for at least 1 year
occurred in April.  Also, suppose the warmest 4 months for that particular
area occurred June-September.  In such cases, ozone monitoring would be
required for April (previous maximum concentration month), May (interval
month), and June-September (warmest 4 months).

     Some situations may occur where a source owner or operator may not
operate a new source or modification at the rated capacity applied for in
the PSD permit.  Generally, the postconstruction monitoring should not
begin until the source is operating at a rate equal to or greater than 50
percent of its design capacity.  However, in no case should the postcon-
struction monitoring be started later than 2 years after the start-up of
the new source or modification.

     If the permit granting authority has determined that less than 1 year
of monitoring data is permissible, the source must agree to use the maximum
values collected over this short period for comparison to all applicable
short-term standards, and the average value for the short period as the
equivalent of the annual standard.

     It should also be noted that the above discussion of less than 1 year
of data pertains to air quality data, not meteorological data. When the air
quality impact must be determined using a dispersion model, the preferred
meteorological data base is at least 1 year of on-site data.  Although less
than 1 year of data may be sufficient to determine the acceptability for a
model, once the model has been accepted, a full year of meteorological data
must be used in the PSD analysis.

2.5.2 Transition Period for PMm and TSP

     The  1987 PSD regulatory changes for particulate matter [6] provide for
a transition period for phasing in the PM^g monitoring data requirements.
The term  "monitoring data" was previously defined in Section 2.1 as the use
of existing representative air quality data or monitoring to determine the
existing  air quality.

2.5.2.1   Transition Within 10 Months After Effective Date of PMm Amendments -
The first  provision of the regulations concerning a transition period is in
section 52.21(i)(ll)(i) and relates  to applications for a PSD permit submitted
not later  than 10 months after the effective date of the 1987 PSD amendments.
During this 10-month period, the permit granting authority has the discretion
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of waiving the preconstruction  monitoring  data requirements  for  the  ambient
air quality analysis discussed  in  Appendix A of this  guideline.   In  all  cases
no applicant would be required  to  initiate monitoring during this  period.
However, the requirement to use existing  air quality  data  would  be discre-
tionary.  The discretion would  be  based in part on  the availability  of
existing air quality data which could include total suspended particulate
matter data, PM^g data, as well as inhalable particulate matter  (PMis)  data.
The PM^5 data would be from samplers with  inlets designed  for a  5C percent
collective efficiency at 15 urn.  The PM^5  data could  be from dichotomous
samplers or high volume samplers with a size selective inlet of  15 urn.

     (a)  Comparing Representative Air Quality Data to PMjp  NAAQS.
In situations where existing PMig  and/or PM^s data  are available,  the data
may be used for describing the  existing air quality levels for comparison
with the PMio NAAQS.  Reference [8] describes procedures for estimating
ambient PM^g concentrations from PMi5 ambient air measurements.   The PMi5 data
multiplied by a correction factor of 0.8 may be assumed to be equivalent to
PMig.  Existing TSP data may only  be used  as a "one-for-one" substitute for
comparison to the Pl^g NAAQS.

     Concerning the priorities  for using existing air quality data,  the
first preference is to use ambient PMig data.  The  second  preference is
to use inhalable particulate (PM^) measurements obtained  with a dichoto-
mous sampler or a size selective high volume sampler.  The third preference
is to use total suspended parti culte (TSP) data. Also, combinations of
the above data may be used.
2.5.2.2  Transition During 10-16 Months After Effective Date of
Amendments^- The second provision of the regulations  concerning a transition
period is in section 52.21(1 )(11)(11) and relates to  applications for a
PSD permit submitted more than 10 months and no later than 16 months  after
the effective date of the 1987 PSD amendments.  If preconstruction monitoring
data are required in the ambient air quality analysis during this 10  to
16-month period, the applicant must use representative air quality data
or collect monitoring data.

     (a)  Comparing Preconstruction Air Quality Data  to PMip NAAQS.
Existing representative PMig  and/or PMis air quality  data may be used
if available.  The priorities and calculations for using these data
were described in Section 2.5.2.1.  Existing TSP data cannot be used  dur-
ing during this transition period.
     If the applicant collects new PMig and/or PMis monitoring data,  the
data should have been collected from the date 6 months after the effective
date of the 1987 PSD amendments to the time the PSD application becomes
otherwise complete.  The preferences for PMig and PM^5 data were previously
discussed.

     (b)  Other Considerations and Explanations.  As discussed in Section
2.5.1, less than the maximum amount of data (10 months in this case)  moni-
toring data will be acceptable if the applicant demonstrates, through


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historical data or dispersion modeling, that the data would be obtained
during a time period when the maximum air quality can be expected.   The
minimum of 4 months of air quality data would still  be required.   The
assumptions for the 10-month figure were derived by  assuming that 5 months
are needed for instrument and equipment procurement, 1 month to install
the equipment, calibrate and ensure satisfactory operation, and a minimum
of 4 months of monitoring data.  The upper range of  16 months after the
effective date for use of non-reference PM^g monitoring is based  on the
assumption that within 11 months after the effective date, reference or
equivalent method samplers for PM^g would be designated by EPA ana  would
be commercially available.  Furthermore, 1 month would be needed  to
install the equipment, calibrate, and ensure satisfactory operation, and
a minimum of 4 months would be needed for gathering  monitoring data.
2.5.2.3  Transition During 16-24 Months After Effective Date of
Amendments - The third transition period provision of the amendments is
in section 52.21(m)(l)(vii ) and relates to applications for a PSD permit
submitted more than 16 months and not later than 24 months after the
effective date of the 1987 PSD amendments.  If preconstruction monitoring
data are required in the ambient air quality analysis during this 16 to
24-month period, the applicant must use representative air quality data
or collect monitoring data.

     (a)  Comparing Preconstruction Air Quality Data to PM\n NAAQS.
If existing representative PMjg and/or PMis air quality data are available
they may be used.  The priorities and calculations for using these data
were described in Section 2.5.2.1.  Existing TSP data cannot be used
during this transition period.  If no PMjg or PMis representative air
quality data are available, the applicant will have to collect monitoring
data using only reference or equivalent PM^o method samplers.  The sampling
must be conducted for at least 12 months during the period from 12 months
after the effective date to the time when the application is completed,
except if the permit granting authority determines that a complete and
adequate analysis can be accomplished with monitoring data over a shorter
period (but in no case less than 4 months).

2*5.2.4  Period Following 24 Months After Effective Date of PMm Amendments -
For applications for a PSD permit submitted later than 24 months after
the effective date, the transition period would no longer be in effect.
If preconstruction monitoring data are required in the ambient air quality
analysis, the applicant must use representative air quality data or
collect monitoring data.

     (a)  Comparing Preconstruction Air Quality Data to PMm NAAQS.  If
existing representative PM^g air quality data are available, they may be
used.  However, existing PM^g representative air quality data collected
later than 24 months after the effective date of the 1987 PSD amendments
must have been collected using reference or equivalent PMig method sam-
plers.  If no PM^o representative air quality data are available, the
applicant will have to collect monitoring data using only reference or
equivalent PMjg method samplers.


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2.6  Sampling Methods and Procedures

     (a)  Criteria pollutants.

          All ambient air quality monitoring must be done with continuous
Reference or Equivalent Methods, with the exception of particulate matter
and lead for which continuous Reference or Equivalent Methods do not exist.
For particulate matter and lead, samples must be taken in accordance with
the Reference Method.  The Reference Methods are described in 40 CFR 50.
A list of designated continuous Reference or Equivalent Methods can be
obtained by writing Environmental Monitoring Systems Laboratory, Department
E (MD-76), U.S. Environmental Protection Agency, Research Triangle Park,
NC 27711.

     (b)  PM^Q Transition for Non-reference Methods
          As discussed in Section 2.5.2, non-reference monitors for
may be used for applications submitted not later than 16 months after the
effective date of the 1987 PSD amendments.  These could include PM^g monitors
as well  as inhalable particulate matter (PMjg)  monitors.  The PMi5 monitors
could be dichotomous monitors or high volume monitors with a size selective
inlet of 15 urn.

     (c)  Noncriteria pollutants.

          For noncriteria pollutants, a list of acceptable measurement
methods  is available upon request by writing Environmental Monitoring
Systems  Laboratory, Quality Assurance Division  (MD-77), U.S. Environmental
Protection Agency, Research Triangle Park, NC 27711.   This list of accept-
able methods will be reviewed at least annually and are available from
the above address.  Measurement methods considered candidates for the
noncriteria pollutant list should be brought to the attention of EPA at
the address given above.

2.7  Frequency of Sampling

     For all gaseous pollutants and for all  meteorological parameters,
continuous analyzers must be used.  Thus, continuous  sampling (over the
time period determined necessary) is required.   For particulate pollu-
tants, except for PMjg, daily sampling (i.e., one sample every 24 hours)
is required except in areas where the applicant can demonstrate that signi-
ficant pollutant variability is not expected.  In these situations, a
sampling schedule less frequent than every day  would  be permitted.  However,
a minimum of one sample every 6 days will be required for these areas.
The sampling frequency would apply to both preconstruction and postcon-
struction monitoring.
     The sampling frequency for PMjg samplers is determined by the
    , or TSP concentrations relative to the PM^Q NAAQS.   The philosophy is
to use existing data where possible to determine the PM^g sampling frequency.
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The frequencies discussed below are consistent with the Part 58 sampling
frequencies [6].  If PMjo data are available but not from the locations as
specified in Section 2.4.1, then modeling could be used in conjunction with
the data to estimate the PMjg concentrations in the appropriate sampling
area(s) to determine the PM^g sampling frequency.  If these estimated concen-
trations were < 80 percent of the PMjg NAAQS, then a minimum of one sample
every 6 days would be required for PM^g monitors; for >j30 - <90 percent of
the PM^g NAAQS, a minimum of one sample every other day would be required;
and for ^90 percent of the PM^g NAAQS every day sampling would be required.
PM]^ data would be treated the same way except the data must be multiplied
by a correction factor of 0.8 to be equivalent to PMjg.

     Reference [8] describes how TSP data may also be used to estimate the
probability of exceeding the PMig NAAQS in the appropriate sampling area(s)
for purposes of determining the PM^g sampling frequency.  If the probabilities
are <  .20 of the PM^g NAAQS, then a minimum of one sample every 6 days would
be required for PM^g monitors; for >_.20 - <.50 probabilities, a minimum of
one sample every other day would be required; and for >_.50 probabilities,
every day sampling would be required.  These probability intervals are in
line with the percent of the NAAQS intervals specified when using PM^g data.
     In those cases where no PM^g, PM^, or TSP data are available to
determine the PM^g sampling frequency, the PM^g expected concentrations
could be estimated by modeling.  These estimated concentrations would be
used to calculate the percentage of the PM^g NAAQS and the resulting PM^g
sampling frequency as discussed above for the cases where PM^g data were
available.

2.8  Monitoring Plan

     A monitoring plan prepared by the source should be submitted to and
approved by the permit granting authority before any PSD monitoring
begins.  Note that approval of the monitoring plan before a monitoring
program is started is not a requirement.  However, since the network
size and station locations are determined on a case-by-case basis, it
would be prudent for the owner or operator to seek review of the network
and the overall monitoring plan from the permit granting authority prior
to collecting data.  This review could avoid delays in the processing of
the permit application and could also result in the elimination of any
unnecessary monitoring.  Delays may result from insufficient, inadequate,
poor, or unknown quality data.  Table 1 lists the types of information
that should be included in the monitoring plan.

2.9  Meteorological Parameters and Measurement Methods

     Meteorological data will be required for input to dispersion models
used in analyzing the impact of the proposed new source or modification
on ambient air quality and the analyses of effects on soil, vegetation,
and visibility in the vicinity of the proposed source.  In some cases,
representative data are available from sources such as the National
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Weather Service.   However,  in some situations,  on-site  data  collection
will  be required.   The meteorological  monitoring  and  instrumentation
considerations are discussed in  Sections  5  and  6.
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              TABLE 1.   MINIMUM  CONTENTS  OF  A MONITORING  PLAN
I.    SOURCE ENVIRONMENT DESCRIPTION  (within  2  km  of  source)

     o  topographical  description
     o  land-use description
     o  topographical  map of  source  and  environs  (including  location  of
        existing stationary sources, roadways,  and monitoring  sites)
     o  climatological  description
     o  quarterly wind roses  (from meteorological data  collected  at  the
        source or other representative meteorological data)

II.  SAMPLING PROGRAM  DESCRIPTION

     o  time period for which the  pollutant(s)  will  be  measured
     o  rationale for  location of monitors  (include  modeling results  and
        analysis of existing  soures  in the  area)
     o  rationale for  joint utilization  of  monitoring network  by  other
        PSD sources

III. MONITOR SITE DESCRIPTION

     o  Universal Transverse  Mercator (UTM)  coordinates
     o  height of sampler (air intake) above ground
     o  distance from  obstructions and heights  of obstructions
     o  distance from  other sources  (stationary and  mobile)
     o  photographs of each site (five photos:  one  in each cardinal  direc-
        tion looking out from each existing sampler  or  where a future
        sampler will be located, and one closeup  of  each existing sampler
        or where a future sampler  will be located.   Ground cover  should  be
        included in the closeup photograph.)

IV.  MONITOR DESCRIPTION

     o  name of manufacturer
     o  description of calibration system to be used
     o  type of flow control  and flow recorder

V.   DATA REPORTING

     o  format of data submission
     o  frequency of data reporting

VI.  QUALITY ASSURANCE PROGRAM

     o  calibration frequency
     o  independent audit program
     o  internal quality control procedures
     o  data precision and accuracy  calculation procedures
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                3.  NETWORK DESIGN AND PROBE  SITING CRITERIA

     A source subject to PSD should proceed with designing a PSD monitoring
network only after going through the procedure in Appendix A to determine
if monitoring data will  be required.  To fulfill that requirement,  a source
may use representative air quality data which was discussed in Section 2.4
or monitor.  This section presents guidance to be used if an applicant
decides to monitor in lieu of using representative air quality data.

3.1  Network Design

     The design of a network for criteria and noncriteria pollutants will
be affected by many factors, such as topography, climatology, population,
and existing emission sources.  Therefore, the ultimate design of a network
for PSD purposes must be decided on a case-by-case basis by the permit
granting authority.  Section 3.2 discusses the number and location  of
monitors for a PSD network.  Additional  guidance on the general  siting of
the monitors may be found in references 9-13  which discuss highest  concen-
tration stations, isolated point sources, effects of topography, etc.
Probe siting criteria for the monitors are discussed in Section 3.3. The
guidelines presented here should be followed  to the maximum extent  practical
in developing the final  PSD monitoring network.

3.2  Number and Location of Monitors

     The number and location of monitoring sites will be determined on a
case-by-case basis by the source owner or operator and reviewed by  the
permit granting authority.  Consideration should be given to the effects of
existing sources, terrain, meteorological conditions, existence of  fugitive
or reentrained dusts, averaging time for the  pollutant, etc.  Generally,
the number of monitors will be higher where the expected spatial variability
of the pollutant in the area(s) of study is higher.

3.2.1  Preconstruction Phase

     Information obtained in the ambient air  quality analysis in Appendix A
will  be used to assist in determining the number and location of monitors
for the preconstruction phase.  The air quality levels before construction
were determined by modeling or in conjunction with monitoring data.  The
screening procedure (or more refined model) estimates were determined in
Appendix A.

     The source should first use the screening procedure or refined model
estimates to determine the general location(s) for the maximum air  quality
concentrations from the proposed source or modification.  Secondly, the
source should determine by modeling techniques the general location(s) for
the maximum air quality levels from existing  sources.  Thirdly, the modeled
pollutant contribution of the proposed source or modification should be
analyzed in conjunction with the modeled results for existing sources to
determine the maximum impact area.  Application of these models must be
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consistent with EPA's "Guideline on  Air Quality Models"  [14].  This  would
provide sufficient information for the applicant to place a  monitor at
(a) the location(s) of the maximum concentration increase expected  from the
proposed source or modification, (b) the location(s)  of  the  maximum air
pollutant concentration from existing sources of emissions,  and  (c)  the
location(s) of the maximum impact area, i.e., where the  maximum  pollutant
concentration would hypothetically occur based on the combination effect of
existing sources and the proposed new source or modification.   In some
cases, two or more of these locations may coincide and thereby reduce the
number of monitoring stations.

     Monitoring should then be conducted in or as close  to these areas  as
possible (also see discussion in Section 3.2.3).  Generally, one to four
sites would cover most situations in multisource settings.  For  remote
areas in which the permit granting authority has determined  that there  are
no significant existing sources, a minimum number of monitors  would be
needed, i.e., one or probably two at the most.  For new  sources, in these
remote areas, as opposed to modifications,  some concessions  will be made on
the locations of these monitors.  Since the maximum impact from  these new
sources would be in remote areas, the monitors may be located, based on
convenience or accessibility, near the proposed new source rather than  near
the maximum impact area since the existing air quality would be  essentially
the same in both areas.  However, the maximum impact area is still  the
preferred location.

     When industrial process fugitive particulate emissions  are  involved,
the applicant should locate a monitor at the proposed source site (also see
Section 3.2.3).  If stack emissions  are also involved, a downwind location
should also be selected.  For fugitive hydrocarbon emissions,  the applicant
should locate a monitor downwind of  the source at the point  of expected
maximum ozone concentration contribution.  This location will  be found
downwind during conditions that are  most conducive to ozone  formation,  such
as temperature above 20°C (68°F) and high solar radiation intensity. For
hydrocarbon emissions from a stack,  the applicant should also locate the
monitor in the area of expected maximum ozone concentration.  For both
fugitive and stack emissions, the selection of areas of  highest  ozone concen-
trations will require wind speed and direction data for  periods  of  photo-
chemical activity.  Monitoring for ozone will only be necessary  during  the
seasons when high concentrations occur.

     Since ozone is the result of a  complex photochemical process,  the  rate
of movement across an area of the air mass containing precursors should be
considered.  The distance from the proposed source to the monitor for an
urban situation should be about equal to the distance traveled by the air
moving for 5 to 7 hours at wind speeds occurring during  periods  of  photo-
chemical activity.  In an urban situation, ozone formation over the initial
few hours may be supressed by nitric oxide (NO) emissions.  For a point
source, the NO interactions may be minimal, and the travel time to  the
expected maximum ozone concentration may be 3 to 4 hours downwind.   In
general, the downwind distance  for the maximum ozone site should generally
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not be more than 15 to 20 miles from the source because a lower wind speed
(2-3 miles per hour)  with less dilution would be a more critical  case.
Additionally, the frequency that the wind would blow from the source over
the site diminishes with increasing distances.

3.2.2  Postconstruction Phase

     As discussed above for preconstruction monitoring, appropriate dis-
persion modeling techniques are used to estimate the location of the air
quality impact of the new source or modification.  Monitors should then be
placed at (a) the expected area of the maximum concentration from the new
source or modification, and (b) the maximum impact area(s), i.e., where the
maximum pollutant concentration will occur based on the combined effect of
existing sources and the new source or modification.  It should be noted
that locations for these monitors may be different from those sites for the
preconstruction phase due to other new sources or modifications in the  area
since the preconstruction monitoring.

     Generally, two or three sites would be sufficient for most situations
in multisource areas.  In remote areas where there are no significant
existing sources, one or two sites would be sufficient.  These sites would
be placed at the locations indicated from the model results.  The same
concerns discussed in Section 3.2.1 regarding industrial process fugitive
particulate emissions, fugitive hydrocarbon emissions, and ozone monitoring
would also be applicable for the postconstruction phase.

3.2.3  Special Concerns for Location of Monitors

     For the preconstruction and postconstruction phases, modeling is used
to determine the general area where monitors would be located. Some of  the
modeled locations may be within the confines of the source's boundary.
However, monitors should be placed in those locations satisfying the defini-
tion of ambient air.   Ambient air is defined in 40 CFR 50.1(e) as "that
portion of the atmosphere, external to buildings, to which the general
public has access."  Therefore, if the modeled locations are within an  area
excluded from ambient air, the monitors should be located downwind at the
boundary of that area.

     In some cases, it is simply not practical to place monitors at the
indicated modeled locations.  Some examples may include over open bodies  of
water, on rivers, swamps, cliffs, etc.  The source and the permit granting
authority should determine on a case-by-case basis alternative locations.

3.3  Probe Siting Criteria

     The desire for comparability in monitoring data requires adherence to
some consistent set of guidelines.  Therefore, the probe siting criteria
discussed below must be followed to the maximum extent possible to ensure
uniform collection of air quality data that are comparable and compatible.
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     Before proceeding with the discussion  of pollutant  specific  probe  siting
criteria, it is important to expand  on  the  discussion  in Section  3.2  of the
location of monitors.  In particular,  reference is  made  to two  monitoring
objectives.

     •  Case 1:  Locating monitors to  determine the maximum concentration
                 from the proposed source and/or existing sources.

     t  Case 2:  Locating monitors to  determine where  the combined  impact
                 of the proposed source and existing sources would  be
                 expected to exhibit the highest concentrations.

     For Case 1, the driving force for locating the siting area of  the
monitor as well as the specific location of the probe  or instrument shelter
is the objective of measuring the maximum impact from  the proposed  source.
Two Case 1 examples are given.  Consider the first  situation in which a
proposed source would be emitting pollutants from an elevated stack.  Under
these circumstances, sufficient mixing generally occurs  during  the  transport
of the emissions from the stack to the ground resulting  in small  vertical
gradients near ground level, thus, a wide range of  probe heights, 3-15  meters
for gases and 2-15 meters for particulates  is acceptable.  For  the  same
objective (maximum concentration from  proposed source),  consider  the  second
example in which pollutants would be emitted from a ground level  source.
In this case, the concentration gradient near the ground can be large,
thereby requiring a much tighter range of acceptable probe heights.  For
ground level sources emitting pollutants with steep vertical concentration
gradients, efforts should be made to locate the inlet  probe for gaseous
pollutant monitors as close to 3 meters (a  reasonable  practical represen-
tation of the breathing zone) as possible and for particulate monitors
using the hi-volume sampler 2 to 7 meters above ground level.  The  ration-
ale for the 3 meters is that for gaseous pollutant measurements,  the inlet
probe can be adjusted for various heights even though  the monitor is  loca-
ted in a building or trailer.  On the  contrary, the 2-3  meter height  for
the hi-volume sampler placement is not practical in certain areas.   The 7
meter height allows for placement on a one  story building and is  reasonably
close to representing the breathing zone.

     Turn now to the second monitoring objective, Case 2, which is  locating
monitors to determine the maximum impact area taking into consideration the
proposed source as well as existing sources.  The critical element  to keep  in
mind in locating a monitor to satisfy  this  objective is  that the  intent is
to maximize the combined effect.  Thus, in  one circumstance, the  existing
source might contribute the largest impact.  The importance of the  above
discussion to the topic of probe siting criteria is that in attempting  to
locate a monitor to achieve this objective, the placement of the  probe  or
instrument shelter can vary depending  upon  which source is the predominant
influence on the maximum impact area.   As an extreme example, consider  the
situation where a proposed elevated source  would emit  CO into an  urban  area
and have maximum combined CO impact coincident to an area adjacent  to a
heavily traveled traffic corridor.  It is known that traffic along  corridors
                                      20

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emit CO in fairly steep concentration gradients so the placement of the probe
to measure the areas of highest CO concentration can vary significantly with
probe height as well as distance from the corridor.  In this example,  the
traffic corridor has the major influence on the combined impact and therefore
controls the probe placement.  As noted in the CO probe siting criteria in
Section 3.3.3 as well  as Appendix E of the May 10, 1979 Federal Register
promulgation of the Ambient Air Monitoring Regulations [7_| and revised and
updated on March 19, 1986 [15], the required probe height in such microscale
cases is given as 3 +_ 1/2 meters while the distance of the probe from  the
roadway would be between 2 and 10 meters.

     As another example, consider the case where the same proposed CO  source
would emit CO at elevated heights and have a combined maximum CO impact in an
urban area that is only slightly affected by CO emissions from a roadway.
The combined impact area in this case is far enough away from the two  sources
to provide adequate mixing and only small vertical concentration gradients at
the impact area.  In this case, the acceptable probe height would be in the
range of 3-15 meters.

     It is recognized that there may be other situations occurring which
prevent the probe siting criteria from being followed.  If so, the differences
must be thoroughly documented.  This documentation should minimize future
questions about the data.

     The desire for comparability in monitoring data requires adherence to
some consistent set of guidelines.  Therefore, the probe siting criteria
discussed below must be followed to the maximum extent possible to ensure
uniform collection of air quality data that are comparable and compatible.
To achieve this goal, the specific siting criteria that are prefaced with a
"must" are defined as a requirement and exceptions must be approved by the
permit granting authority.  However, siting criteria that are prefaced with
a "should" are defined as a goal to meet for consistency, but are not  a
requirement.

3.3.1  Total Suspended Particulates (TSP)

     Section 3.3.1 is applicable only for the following cases.  PSD
applications submitted not later than 6 months after the effective date of
the 1987 PSD amendments would use this siting criteria when collecting TSP
monitoring data.  Also, representative air quality data for TSP collected
not later than 6 months after the effective date of the 1987 PSD amendments
would use this siting criteria.

3.3.1.1  Vertical Placement - The most desirable height for a TSP monitor
is near the breathing zone.  However, practical considerations such as
prevention of vandalism, security, accessibility, availability of electri-
city, etc., generally require that the sampler be elevated.  Therefore, a
range of acceptable heights needs to be used.  In addition, the type of
source, i.e., elevated or ground level, predominantly influencing the  area
of impact must be considered when locating the monitor.  For purposes  of
                                      21

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determining elevated source impact,  the sampler air intake must be located
2-15 meters above ground level.   The lower limit was based on  a compromise
between ease of servicing the sampler and the desire to avoid  reentrainment
from dusty surfaces.  The upper  limit represents a compromise  between  the
desire to have measurements which are most representative of population
exposures, and the considerations noted earlier.  For ground level  sources
with steep vertical concentration gradients,  the air intake must be as close
to the breathing zone as practical.

3.3.1.2  Spacing from Obstructions - If the sampler is located on a roof or
other structure, then there must be  a minimum of 2 meters separation from
walls, parapets, penthouses, etc.  Furthermore, no furnace or  incineration
flues should be nearby.  The separation distance from flues is dependent on
the height of the flues, type of waste or fuel burned, and quality of  the
fuel (ash content).  For example, if the emissions from the chimney are the
result of natural gas combustion, no special  precautions are necessary except
for the avoidance of obstructions, i.e., at least 2 meters separation.  On
the other hand, if fuel oil, coal, or solid waste is burned and the stack is
sufficiently short so that the plume could reasonably be expected to impact
on the sampler intake a significant  part of the time, other buildings/locations
in the area that are free from these types of sources should be considered
for sampling.  Trees provide surfaces for particulate deposition and also
restrict airflow.  Therefore, the sampler should be placed at  least 20 meters
from the dripline of trees and must  be 10 meters from the dripline when
trees act as an obstruction [15],

     Obstacles such as buildings must also be avoided so that  the distance
between obstacles and the sampler is at least twice the height that the
obstacle protrudes above the sampler.  In addition, there must be unre-
stricted airflow in an arc of at least 270° around the sampler, and the
predominant direction for the season of greatest pollutant concentration
potential must be included in the 270° arc.

3.3.1.3  Spacing from Roads - A number of studies [16-23] support the
conclusion that particulate concentrations decrease with increasing height
of the monitor and distance from the road.  Quite high concentrations  have
been reported at monitors located at a low elevation close to heavily tra-
veled roads.  Moreover, monitors located close to streets are within the
concentrated plume of particulate matter emitted and generated by vehicle
traffic.  Therefore, ambient monitors for TSP should be located beyond the
concentrated particulate plume generated by traffic, and not so close that
the heavier reentrained roadway particles totally dominate the measured
ambient concentration.

     An analysis of various monitoring studies [24] shows that a linear
relationship between sampler height and distance from roadways defines a
zone where the plume generated by traffic greater than approximately 3,000
vehicles per day is diminished.  Figure 1 illustrates this relationship by
showing two zones where TSP monitors could be located.  Zone A represents
locations which are recommended and Zone B represents locations which
                                      22

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should be avoided in order to minimize undesirable roadway influences.   Roads
with lower traffic (less than approximately 3,000 vehicles per day)  are
generally not considered to be a major source or vehicularrelated  pollutants,
and so as noted in Figure 1 do not preclude the use of monitors in Zone  B for
those situations.  However, note that for those cases  where the traffic  is
less than approximately 3,000 vehicles per day, the monitor must be  located
greater than 5 meters from the edge of the nearest traffic lane and  2 to 15
meters above ground level.

     In the case of elevated roadways where the monitor must be placed below
the level of the roadway, the monitor should be located no closer  than approx-
imately 25 meters from the edge of the nearest traffic lane.  This separation
distance applies for those situations where the road is elevated greater than
5 meters above the ground level, and applies to all traffic volumes.

3.3.1.4  Other Considerations - Stations should not be located in  an unpaved
area unless there is vegetative ground cover year round so that the  impact
of reentrained or fugitive dusts will be kept to a minimum.  Additional
information on TSP probe siting may be found in reference 9.

3.3.2  PMin

3.3.2.1.  Vertical Placement - Although there are limited studies  on the
PMiQ concentration gradients around roadways or other ground level sources,
references 16, 17, 19, 25, and 26 show a distinct variation in the distribu-
tion of TSP and Pb levels near roadways.  TSP, which is greatly affected by
gravity, has large concentration gradients, both horizontal and vertical,
immediately adjacent to roads.  Pb, being predominantly submicron  in size,
behaves more like a gas and does not exhibit steep vertical and horizontal
gradients as does TSP.  PM^o» being intermediate in size between these two
extremes exhibits dispersion properties of both gas and settleable particu-
lates and does show vertical and horizontal gradients [27].  Similar to
monitoring for other pollutants, optimal placement of the sampler  inlet  for
PM^g monitoring should be at breathing height level.  However, practical
factors such as prevention of vandalism, security, and safety precautions
must also be considered when siting a PMio monitor.  Given these considera-
tions, the sampler inlet for ground level source monitoring must be 2-7
meters above ground level.  For PM^o samplers, the acceptable range for
monitoring emissions from elevated sources is 2-15 meters above ground
level.

3.3.2.2  Spacing from Obstructions - If the sampler is located on  a roof or
other structure, then there must be a minimum of 2 meters separation from
walls, parapets, penthouses, etc.  No furnace or incineration flues should
be nearby.  This separation distance from flues is dependent on the height
of the flues, type of waste or fuel burned, and quality of the fuel  (ash
content).  In the case of emissions from a chimney resulting from  natural
gas combustion, the sampler should be placed, as a precautionary measure,
at least 5 meters from the chimney.
                                      24

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     On the other hand,  if fuel  oil,  coal,  or  solid  waste  is  burned  and  the
stack is sufficiently short so that the  plume  could  reasonably  be  expected
to impact on the sampler intake a significant  part of  the  time, other
buildings/locations in the area that  are free  from these types  of  sources
should be considered for sampling.  Trees provide surfaces for  particulate
deposition and also restrict airflow. Therefore, the  sampler should be
placed at least 20 meters from the  dripline of trees and must be 10  meters
from the dripline when trees act as an obstruction [15],

     The sampler must also be located away  from obstacles  such  as  buildings,
so that the distance between obstacles and  the sampler is  at  least twice
the height that the obstacle protrudes above the sampler.   There must  also
be unrestricted airflow in an arc of  at  least  270° around  the sampler,  and
the predominant wind direction for  the season  of greatest  pollutant
concentration potential  must be included in the 270° arc.

3.3.2.3  Spacing from Roads - For these  situations where the  emissions  from
a proposed source would impact close  to  a roadway, the air intake  for  the
monitor must be located between 5-15  meters from the edge  of  the nearest
traffic lane.  Monitors located in  this  area would thus measure the  combined
impact from the proposed source and the  roadway. The  sampler air  intake
must be 2-7 meters above ground level.

3.3.2.4  Other Considerations - Stations should not  be located  in  an unpaved
area unless there is vegetative ground cover year round so that the  impact
of reentrained or fugitive dusts will be kept  to a minimum.  Additional
information on PM^g siting may be found  in  reference 28.

3.3.3  Sulfur Dioxide (SO?)

3.3.3.1.  Horizontal and Vertical Probe  Placement -  As with TSP monitoring,
the most desirable height for an SOg  inlet  probe is  near the  breathing
height.  Various factors enumerated before may require that the inlet  probe
be elevated,  consideration must also be given to the  type of source pre-
dominantly influencing the impact area.   For elevated  sources,  the inlet
probe must be located 3 to 15 meters  above  ground level.   For ground level
sources, locate as close to the breathing zone as possible.  If the  inlet
probe is located on the side of the building,  then it  should  be located  on
the windward side of the building relative  to  the prevailing  winter  wind
direction.  The inlet probe must also be located more  than 1  meter vertically
or horizontally away from any supporting structure and also away from
dirty, dusty areas.

3.3.3.2  Spacing from Obstructions  -   No furnace or  incineration flues,  or
other minor sources of S02 should be  nearby.  The separation  distance  is
dependent on the height of the flues, type of  waste  or fuel burned,  and  the
quality of the fuel (sulfur content).  If the  inlet  probe  is  located on  a
roof or other structure, it must be at least 1 meter from  walls, parapets,
penthouses, etc.
                                      25

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     The inlet probe should be placed at least 20 meters  from the drip-
line of trees and must be 10 meters from the dripline when  trees  act  as
an obstruction [15].  Additionally, the probe must be located away from
obstacles and buildings.  The distance between the obstacles  and  the  inlet
probe must be at least twice the height that the obstacle protrudes above
the inlet probe.  Airflow must also be unrestricted in an arc of  at least
270° around the inlet probe, and the predominant direction  for the season of
greatest pollutant concentration potential  must be included in the 270°
arc.  If the probe is located on the side of a building,  180° clearance is
required.  Additional information on S02 probe siting criteria may be found
in reference 10.

3.3.4  Carbon Monoxide (CO)

3.3.4.1  Horizontal and Vertical Probe Placement - Because  of the importance
of measuring population exposure to CO concentrations, optimum CO sampling
should be done at average breathing heights.  However, practical  factors
require that the inlet probe be higher.  In general, for  CO emitted at
elevated heights, the inlet probe for CO monitoring should  be 3-15 meters
above ground level.  For those situations where the emissions from a  pro-
posed source would impact a street canyon or corridor type  area in an urban
area, and the area is predominantly influenced by the traffic from the
street canyon or traffic corridor, the inlet probe should be  positioned 3 +_
1/2 meters above ground level which coincides with the vertical probe
placement criteria for a street canyon/corridor type site [7].  The criteria
is more stringent than the 3 to 15 meter range specified  earlier  because CO
concentration gradients resulting from motor vehicles traveling along
street canyon or corridors are rather steep and show wide variations  in CO
levels at different heights.  The 3 meter height is a compromise  between
breathing height representation and such factors as the prevention of
obstructions to pedestrians, vandalism, etc.

     In addition to the vertical probe criteria, the inlet  probe  must also
be located more than 1 meter in the vertical or horizontal  direction  from
any supporting structure.

3.3.4.2  Spacing from Obstructions - Airflow must also be unrestricted in
an arc of at least 270° around the inlet probe, and the predominant direction
for the season of greatest pollutant concentration potential  must be  included
in the 270° arc.  If the probe is located on the side of  a building,  180°
clearance is required [7, 15].  Additionally, trees should not be located
between the major sources of CO and the sampler.  The sampler must be at
least 10 meters form the dripline of a tree which is between the sampler
and the source if the tree extends at least 5 meters above the sampler [15].

3.3.4.3  Spacing from Roads - For those situations discussed above where
the emissions from a proposed source would impact a street canyon/corridor
type area, the inlet probe must be located at least 10 meters from an
intersection and preferably at a midblock location.  The inlet probe  must
also be placed 2-10 meters from the edge of the nearest traffic lane.
                                      26

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Also no trees or shrubs should be located between the sampling inlet
probe and the road [15],  Additional  information on CO probe siting may be
found in reference 11.

3.3.5  Ozone
3.3.5.1  Vertical and Horizontal  Probe Placement - The inlet probe for
ozone monitors should be as close as possible to the breathing zone.  The
complicating factors discussed previously, however, require that the probe
be elevated.  The height of the inlet probe must be located 3 to 15 meters
above ground level.  The probe must also be located more than 1 meter
vertically or horizontally away from any supporting structure.

3.3.5.2  Spacing from Obstructions - The probe must be located away from
obstacles and buildings such that the distance between the obstacles and
the inlet probe is at least twice the height that the obstacle protrudes
above the sampler.  The probe should also be located at least 20 meters
from the dripline of trees.  Since the scavenging effect of trees is greater
for ozone than for some of the other pollutants, strong consideration should
be used in locating the inlet probe to avoid this effect.  Therefore, the
sampler must be at least 10 meters from the dripline of trees that are
located between the source of the ozone precursors and the sampler along
the predominant summer daytime wind direction [15],  Airflow must be un-
restricted in an arc of at least  270° around the inlet probe, and the pre-
dominant direction for the season of greatest pollutant concentration
potential must be included in the 270° arc.  If the probe is located on the
side of a building, 180° clearance is required.

3.3.5.3  Spacing from Roads - It  is important in the probe siting process
to minimize destructive interferences from sources of nitric oxide (NO)
since NO readily reacts with ozone.  Regarding NO from motor vehicles,
Table 2 provides the required minimum separation distances between roadways
and ozone monitoring stations.  These distances were based on recalculations
using the methodology in reference 12 and validated using more recent
ambient data collected near a major roadway.  The minimum separation distance
must also be maintained between an ozone station and other similar volumes
of automotive traffic, such as parking lots.  Additional  information on
ozone probe siting criteria may be found in reference 12.
                                      27

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       Table 2.  MINIMUM SEPARATION DISTANCE BETWEEN OZONE MONITORS
                    AND ROADWAYS (EDGE OF NEAREST TRAFFIC LANE)

     Roadway Average Daily Traffic,Minimum Separation Distance Between
	Vehicles Per Day	Roadways and Monitors, Meters

            < 10,000                              >_ 10a
              15,000                                20
              20,000                                30
              40,000                                50
              70,000                               100
            >UO,000                              X250

aDistances should be interpolated based on traffic flow.


3.3.6  Nitrogen Dioxide (NO?)

3.3.6.1  Vertical and Horizontal Probe Placement - As discussed for previous
pollutants, the acceptable ranges for a monitor/probe inlet for monitoring
N02 emissions in an area principally influenced by an elevated source is
3-15 meters.  For areas influenced primarily by a ground level source, the
height should be as close to 3 meters as possible.  Regarding the distance
of the probe from the supporting structure, a vertical or horizontal distance
of 1 meter must be maintained.

3.3.6.2  Spacing from Obstructions - Buildings, trees, and other obstacles
can serve as scavengers of N02.  In order to avoid this kind of interfer-
ence, the station must be located well away from such obstacles so that the
distance between obstacles and the inlet probe is at least twice the height
that the obstacle protrudes above the probe.  Also, a probe inlet along a
vertical wall is undesirable because air moving along that wall may be
subject to possible removal mechanisms.  Similarly, the inlet probe should
also be at least 20 meters from the dripline of trees and must be at least
10 meters from the dripline of trees which protrude above the height of
the probe by 5 of more meters [15].  There must be unrestricted airflow in an
arc of at least 270° around the inlet probe, and the predominant direction for
the season of greatest pollutant concentration potential must be included in
the 270° arc.  If the probe is located on the side of the building, 180°
clearance is required.  Additional information on N02 probe siting criteria
may be found in reference 12.

3.3.7  Lead  (Pb)

3.3.7.1  Vertical Placement - Breathing height is the most desirable location
for the vertical placement of the Pb monitor.  However, practical factors
previously mentioned require that the monitor be elevated.  In elevating
the sampler, consideration must be given to ground level emissions (whether
they be stationary or mobile sources) with steep vertical concentration
gradients.   Placing the shelter too high could result in measured values
                                      28

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significantly lower than the level  breathed  by  the  general  public.   Accord-
ingly, the sampler for ground level  source monitoring  must  be  located  2  to
7 meters above ground level.  In  contrast, samplers to monitor for  elevated
sources, as noted in previous discussion, are allowed  a wider  range of
heights for locating the sampler/inlet  probe.   For  Pb  samplers,  the acceptable
range for monitoring emissions from elevated sources is 2-15 meters above
ground level.

3.3.7.2  Spacing from Obstructions  - A  minimum  of 2 meters  of  separation
from walls, parapets, and penthouses is required  for samplers  located  on a
roof or other structure.  No furnace or incineration flues  should be nearby.
The height of the flues and the type, quality,  and  quantity of waste or
fuel burned determine the separation distances  from flues.  For example, if
the emissions from the chimney have a high lead content and there is a high
probability that the plume would  impact on the  sampler during  most  of  the
sampling period, then other buildings/locations in  the area that are free
from the described sources should be chosen  for the monitoring site.  The
sampler should be placed at least 20 meters  from  the dripline  of trees and
must be at least 10 meters from the dripline of trees  when  the tree(s) could
be classified as an obstruction [15], since  trees absorb particles  as  well
as restrict airflow.

     The sampler must be located  away from obstacles such as buildings,  so
that the distance between obstacles and the  sampler is at least twice  the
height that the obstacle protrudes  above the sampler.   There must also be
unrestricted airflow in an arc of at least 270° around the  sampler, and  the
predominant direction for the season of greatest  pollution  concentration
potential must be included in the 270°  arc.

3.3.7.3  Spacing from Roads - For those situations  discussed in Section
3.3.7.1 where the emissions from  a  proposed  source  would impact close  to a
major roadway (greater than approximately 30,000  ADT), the  air intake  for
the monitor must be located within  15-30 meters from the edge  of the nearest
traffic lane.  Monitors located in  this area would  thus measure the combined
impact from the proposed source and the roadway.  The  sampler  air intake
must be 2 to 7 meters above ground  level.

3.3.7.4  Other Considerations - Stations should not be located in an unpaved
area unless there is vegetative ground  cover year round so  that the impact
of reentrained or fugitive dusts  will be kept to  a  minimum. Additional
information on Pb siting criteria may be found  in reference 13.

3.3.8  Noncriteria Pollutants

3.3.8.1  Vertical Placement - Similar to the discussion on  criteria pollutants,
the most desirable height for monitors/inlet probes for noncriteria pollutants
is near the breathing zone.  Again, practical factors  require  that  the
monitor/ inlet probe be elevated.  Furthermore, consideration  must  be  given
to the type of source, i.e., elevated,  ground level, stationary, or mobile.
As the case may be, for noncriteria particulate pollutant monitors, the
                                     29

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following monitor/inlet probe ranges are acceptable:  for impact areas pre-
dominantly influenced by elevated sources, 2-15 meters;  for ground level
sources 2 to 7 meters.  Regarding noncriteria gaseous pollutants, acceptable
heights are as follows:  areas impacted primarily by  elevated sources, 3-15
meters; areas affected principally by ground level  sources, as close to 3
meters as possible.

3.3.8.2  Spacing from Obstructions - If the sampler/inlet probe is located
on a roof or other structure, then there must be a  minimum of 2 meters
separation from walls, parapets, penthouses, etc.  No furnace or inciner-
ation flues should be nearby.  This separation distance  from flues is
dependent on the height of the flues, type of waste or fuel burned, and
quality of the fuel.  For example, if the emissions from the chimney contain
a high concentraton of the noncriteria pollutant that is being measured and
there is a high probability that the plume would impact  the sampler/inlet
probe during most of the sampling period, then other  buildings/locations
in the area that are free from the described sources  should be chosen for
the monitoring site.  The sampler/inlet probe should  also be placed at
least 20 meters from the dripline of trees and must be at least 1C meters
from the dripline of tree(s) that could be classified as an obstruction [15].

     The sampler/inlet probe must be located away from obstacles and buildings
such that the distance between the obstacles and the  sampler/inlet probe
is at least twice the height that the obstacle protrudes above the sampler/
inlet probe.  Airflow must be unrestricted in an arc  of  at least 270°
around the sampler/inlet probe, and the predominant direction for the
season of greatest pollutant concentration potential  must be included in
the 270° arc.  If the inlet probe is located on the side of a building,
180° clearance is required.

3.3.8.3  Other Considerations - Stations for measuring particulate non-
criteria pollutants should not be located in an unpaved  area unless there
is vegetative ground cover year round so that the impact of reentrained or
fugitive dusts will be kept to a minimum.

3.4  Probe Material and Pollutant Sample Residence Time

     For reactive gases, special probe material must  be used.  Studies
[29-33] have been conducted to determine the suitability of materials such
as polypropylene, polyethylene, polyvinylchloride, tygon, aluminum, brass,
stainless steel, copper, pyrex glass, and teflon for use as intake sampling
lines.  Of the above materials, only pyrex glass and  teflon have been found
to be acceptable for use as intake sampling lines for all the reactive
gaseous pollutants.  Furthermore, EPA [34] has specified borosilicate glass
or FEP teflon as the only acceptable probe materials for delivering test
atmospheres in the determination of reference or equivalent methods.
Therefore, borosilicate glass, FEP teflon, or their equivalent must be used
for inlet probes.
                                     30

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     No matter how unreactive the sampling probe  material  is  initially,
after a period of use, reactive participate matter  is  deposited  on  the
probe walls.  Therefore, the time it takes the gas  to  transfer from the
probe inlet to the sampling device is also critical.   Ozone in the  presence
of NO will  show significant losses even  in the most inert  probe  material  when
the residence time exceeds 20 seconds [35].  Other  studies [36-37]  indicate
that a 10-second or less residence time  is easily achievable.  Therefore,
sampling probes for reactive gas monitors  must have a  sampler  residence
time less than 20 seconds.

3.5  Summary of Probe Siting Requirements

     Table 3 presents a summary of the requirements for  probe  siting criteria
with respect to distances and heights.  These criteria are specified for
consistency between pollutants and to allow the use of a single  manifold
for monitoring more than one pollutant at  a site.
                                     31

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                 4.  QUALITY ASSURANCE FOR AIR QUALITY  DATA


     On May 10, 1979, EPA promulgated quality assurance requirements  for
PSD monitoring for $03, N02, 03, CO,  and TSP.  These quality assurance
requirements were revised and updated on March 19,  1986 [15].  These  quality
assurance requirements are Appendix B of 40 CFR 58  (reference 7).   Section
4.1 describes minimum quality assurance requirements for PSD monitoring for
all criteria air pollutants (S02, N02, 03, CO, TSP, Pb  and PMio).   Monitoring
organizations are required to meet quality assurance requirements  of  Appendix
B at the time the station is put into operation.

     Currently, quality assurance for PSD monitoring for noncriteria  air
pollutants are EPA recommendations only.  EPA promulgated requirements are
not available for noncriteria air pollutants.  Section  4.2 describes  minimum
quality assurance recommendations for noncriteria air pollutants.


4.1   Quality Assurance for Criteria  Air Pollutants

4.1.1  General Information

     The following specifies the minimum quality assurance requirements of
an organization operating a network of PSD stations.  These requirements
are regarded as the minimum necessary for the control and assessment  of the
quality of the PSD ambient air monitoring data submitted to EPA. Organiza-
tions are encouraged to develop and implement quality assurance programs
more extensive than the minimum required or to continue such programs
where they already exist.

     Quality assurance consists of two distinct and equally important
functions.  One function is the assessment of the quality of the monitoring
data by estimating their precision and accuracy.  The other function  is the
control, and improvement, of the quality of the monitoring data by implemen-
tation of quality control policies, procedures, and corrective actions.
These two functions form a control loop;  when the  assessment function
indicates that the data quality is inadequate, the  control effort  must
be increased until the data quality is acceptable.

     In order to provide uniformity in the assessment and reporting of data
quality, the assessment procedures are specified explicitly in Sections
4.1.3, 4.1.4, 4.1.5 and 4.1.6.

     In contrast, the control and corrective action function encompasses a
variety of policies, procedures, specifications, standards, and corrective
measures which have varying effects on the resulting data quality. The
selection and degree of specific control measures and corrective actions
used depend on a number of factors such as the monitoring methods  and
equipment used, field and laboratory  conditions, the objectives of the
monitoring, the level of data quality needed, the expertise of personnel,
the cost of control procedures, pollutant concentration levels, etc.


                                      38

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Accordingly, quality control requirements are specified in general  terms,
in Section 4.1.2 to allow each organization to develop a quality control
system which is most effective for its own circumstances.

     For purposes here, "organization" is defined as a source owner/operator,
a government agency, or their contractor which operates an ambient  air
pollution monitoring network for PSD purposes.

4.1.2  Qua!ity Control Requirements

4.1.2.1  Organizational Requirements -  Each organization must develop and
implement a quality control  program consisting of policies, procedures,
specifications, standards and documentation necessary to:

     (a)  meet the monitoring objectives and quality assurance requirements
of the permit granting authority

     (b)  minimize loss of air quality data due to malfunctions or out-
of-control conditions,

     The quality control program must be described in detail, suitably
documented, and approved by the permit granting authority.

4.1.2.2  Primary Guidance - Primary guidance for developing the quality
control program is contained in references 38 and 39, which also contain
many suggested procedures, checks, and control specifications.  Section
2.0.9 of reference 39 describes the specific guidance for the development
of a quality control program for PSD automated analyzers and manual methods.
Many specific quality control checks and specifications for manual  methods
are included in the respective reference methods described in 40 CFR 50, or
in the respective equivalent method descriptions available from EPA (see
Section 2.6).  Similarly, quality control procedures related to specifically
designated reference and equivalent analyzers are contained in their respective
operation and instruction manuals.  This guidance, and any other pertinent
information from appropriate sources, should be used by organizations in
developing their quality control programs.

     As a minimum each quality control program must have operational
procedures for each of the following activities:

     (a)  selection of methods, analyzers, or samplers,
     (b)   installation of equipment,
     (c)  calibration,
     (d)  zero and span checks and adjustments of automated analyzers,
     (e)  control checks and their frequency,
     (f)  control limits for zero, span and other control checks, and
           respective corrective actions when such limits are surpassed,
     (g)  calibration  and zero/span checks for multiple  range analyzers
     (h)  preventive and remedial maintenance
     (i)   recording and validating data
     (j)  documentation of quality control information.


                                      39

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     As previously mentioned,  specific guidance for each activity listed
above that must be a part of an  organization's  quality control  program is
described in Section 2.0.9 of  reference 39.

4.1.2.3  Pollutant Standards - Gaseous standards (permeation tubes,
permeation devices or cylinders  of compressed gas)  used to obtain test
concentrations for CO, S02, and  NOg must be  working standards certified by
comparison to a National  Bureau  of Standards (NBS)  gaseous Standard  Reference
Material  (SRM).  A traceability  protocol for certifying a working standard
by direct comparison to an NBS SRM is given  in  reference 40.  Direct use of
an NBS SRM as a working standard is not prohibited  but is discouraged
because of the limited supply  and expense of NBS SRM's.  When available,
gas manufacturers' cylinder gases Certified  Reference Materials "CRM" may
be substituted for NBS SRM cylinder gases in establishing traceability.

     Test concentrations for ozone must be obtained in accordance with the
UV photometric calibration procedure specified  in Appendix 0 of 40 CFR 50,
or by means of an ozone transfer standard which has been certified.   Consult
reference 41 for guidance on ozone transfer  standards.

     Flow measurements must be made by a flow measuring instrument which is
traceable to an authoritative volume or other standard.

4.1.2.4  Performance and System Audit Programs  - The organization operating
a PSD monitoring network must  participate in EPA's  national performance
audit program.  The permit granting authority,  or EPA, may conduct system
audits of the ambient air monitoring programs of organizations operating
PSD networks.  See Section 1.4.16 of reference 38 and Sections 2.0.11 and
2.0.12 of reference 39 for additional information about these programs.
Organizations should contact either the appropriate EPA Regional  Quality
Control Coordinator or the Quality Assurance Division, EMSL/RTP,  at  the
address given in reference 40  for instructions  for  participation.

4.1.3  Data Quality Assessment Requirements

4.1.3.1  Precision of Automated  Methods - A  one-point precision check must
be carried out at least once every two weeks on each automated analyzer
used to measure S02, N02, 03,  and CO.  The precision check is made by
challenging the analyzer with  a  precision check gas of known concentration
between 0.008 and 0.10 ppm for S02, N02, and 03 analyzers, and between 8 and
10 ppm for CO analyzers.  The  standards from which  precision check test con-
centrations are obtained must  meet the specifications of section  4.1.2.3.
Except for certain CO analyzers  described below, analyzers must operate in
their normal sampling mode during the precision check, and the test  atmosphere
must pass through all filters, scrubbers, conditioners, and other components
used during normal ambient sampling and as much of  the ambient air inlet
system as is practicable.  If  permitted by the associated operation  or
instruction manual, a CO analyzer may be temporarily modified during the
precision check to reduce vent or purge flows,  or the test atmosphere may
                                     40

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enter the analyzer at a point other than the normal  sample inlet, provided
that the analyzer's response is not likely to be altered by these deviations
from the normal operational  mode.

     If a precision check is made in conjunction with zero/span adjustment,
it must be made prior to such zero and span adjustments.  The difference
between the actual concentration of the precision check gas and the concen-
tration indicated by the analyzer is used to assess  the precision of the
monitoring data as described in Section 4.1.4.1.  Report data only from
automated analyzers that are approved for use in the PSD network.

4.1.3.2  Accuracy of Automated Methods - Each sampling quarter audit each
analyzer that monitors for S02, N02, 03, or CO at least once.  The audit is
made by challenging the analyzer with at least one audit gas of known
concentration from each of the following ranges which fall within the
measurement range of the analyzer being audited:
                                      Concentration Range, ppm
Audit Point
S02, 03
NOg
                                                                  CO
1
2
3
4
0.03 to 0.08
0.15 to 0.20
0.35 to 0.45
0.80 to 0.90
0.03 to 0.08
0.15 to 0.20
0.35 to 0.45

3 to 8
15 to 20
35 to 45
80 to 90
The standards from which audit gas test concentrations are obtained must
meet the specifications of Section 4.1.2.3.  Working and transfer standards
and equipment used for auditing must be different from the standards and
equipment used for calibration and spanning.  The auditing standards and
calibration standards may be referenced to the same NBS SRM or primary UV
photometer.  The auditor must not be the operator/analyst who conducts the
routine monitoring, calibration, and analysis.

     The audit shall be carried out by allowing the analyzer to analyze an
audit test atmosphere in the same manner as described for precision checks
in Section 4.1.3.1.  The exception given in Section 4.1.3.1 for certain CO
analyzers does not apply for audits.

     The difference between the actual concentration of the audit test gas
and the concentration indicated by the analyzer is used to assess the
accuracy of the monitoring data as described in Section 4.1.4.2.  Report
data only from automated analyzers that are approved for use in the PSD
network.
                                     41

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4.1.3.3  Precision of Manual  Methods - (a)  TSP and PMm Methods.   For a given
organi zation's monitoring network, one sampling site must have col 1 ocated
samplers.  A site with the highest expected 24-hour pollutant concentration
must be selected.  The two samplers must be within 4 meters of each other
but at least 2 meters apart to preclude airflow interference.  Calibration,
sampling, and analysis must be the same for both collocated samplers as well
as for all other samplers in the network.  The collocated samplers  must be
operated as a minimum every third day when  continuous sampling is  used.
When a less frequent sample schedule is used,  the collocated samplers must
be operated at least once each week.  For each pair of collocated  samplers,
designate one sampler as the sampler which  will be used to report  air quality
for the site and designate the other as the duplicate sampler.  The differences
in measured concentration ( g/m3) between the  two collocated samplers are
used to calculate precision as described in Section 4.1.5.1.

     (b)  Pb Methods.  The operation of collocated samplers at one  sampling
site must be used to assess the precision of the reference or an equivalent
lead method.  The procedure to be followed  for lead methods is the  same as
described in 4.1.3.3(a) for the TSP and PMio methods.
4.1.3.4  Accuracy of Manual  Methods - (a)  TSP and PMm Methods.   Each
sampling quarter audit the flow rate of each sampler at least once.   Audit the
flow at the normal flow rate, using a certified flow transfer standard (see
reference 39).  The flow transfer standard used for the audit must not be
the same one used to calibrate the flow of the sampler being audited,
although both transfer standards may be referenced to the same primary flow
or volume standard.  The difference between the audit flow measurement and
the flow indicated by the sampler's flow indicator is used to calculate
accuracy, as described in Section 4.1.5.2

     Great care must be used in auditing high-volume samplers having flow
regulators because the introduction of resistance plates in the audit
device can cause abnormal flow patterns at the point of flow sensing.  For
this reason, the orifice of the flow audit device should be used with a
normal glass fiber filter in place and without resistance plates in  auditing
flow regulated high-volume samplers, or other steps should be taken  to
assure that flow patterns are not perturbed at the point of flow sensing.

     (b)  Pb Methods.  For the reference method (Appendix G of 40 CFR 50)
each sampling quarter audit the flow rate  of each high-volume lead sampler
at least once.  Audit the flow rate at one flow rate using a reference flow
device described in Section 2.2.8 of reference 39, or a similar flow transfer
standard.  The device used for auditing must be different from the one used
to calibrate the flow of the high-volume sampler being audited.   The auditing
device and the calibration device may both be referenced to the same primary
flow standard.  With the audit device in place, operate the high-volume
sampler at its normal flow rate.  The difference in flow rate (in m3/min)
between the audit flow measurement and the flow indicated by the sampler's
normal flow indicator are used to calculate accuracy as described in Section
4.1.5.3.
                                      42

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     Great care must be used in auditing high-volume sampler having flow
regulators because the introduction of resistance plates  in the audit
device can cause abnormal  flow patterns at the point of flow sensing.   For
this reason, the orifice of the flow audit device should  be used with  a
normal glass fiber filter in place without resistance plates to audit  flow
regulated high-volume samplers, or other steps should be  taken to assure
that flow patterns are not perturbed at the point of flow sensing.

     Each sampling quarter, audit the lead analysis using glass fiber
filter strips containing a known quantity of lead.  Audit samples are
prepared by depositing a lead solution on 1.9 cm by 20.3  cm (3/4 inch  by 8
inch) unexposed glass fiber filter strips and allowing to dry thoroughly.
The audit samples must be prepared using reagents different from those used
to calibrate the lead analytical equipment being audited.  Prepare audit
samples in the following concentration ranges:

                                                   Equivalent Ambient
      Range        Cone, ug Pb/strip                Cone, ug Pb/m^*

       1              100 to 300                     0.5  to 1.5

       2              600 to 1000                    3.0  to 5.0

*Equivalent ambient lead concentration in ug/nr* is based  on sampling at 1.7
m-Vmin for 24 hours on 20.3 cm x 25.4 (8 inch x 10 inch)  glass fiber filter.

     Audit samples must be extracted using the same extraction procedure
used for exposed filters.

     Analyze at least one audit sample in each of the two ranges each  day
that samples are analyzed.  The difference between the audit concentration
(in ug Pb/strip) and the analyst's measured concentration (in ug Pb/strip)
are used to calculate analysis accuracy as described in Section 4.1.5.4.

     The accuracy of an equivalent method is assessed in the same manner as
the reference method.  The flow auditing device and lead analysis audit
samples must be compatible with the specific requirements of the equivalent
method.

4.1.4  Calculations for Automated Methods

4.1.4.1  Single Analyzer Precision - Each organization, at the end of  each
sampling quarter, shall calculate and report a precision probability interval
for each analyzer.  Directions for calculations are given below and directions
for reporting are given in Section 4.1.6.  If monitoring data are  invalidated
during the period represented by a given precision check, the results  of
that  precision check shall be excluded from the calculations.  Calculate
the percentage difference  (dj) for each precision check using equation 1.
                                     43

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                              Y •  - X •
                              I-,  - A-,
                                      X 100
where:  Y-j = analyzer's indicated concentration from the i-th precision
             check,
       X-j = known concentration of the test gas used for the i-th precision
            check.

For each instrument, calculate the quarterly average (dj), equation 2, and
the standard deviation (Sj), equation 3.

                                                                     (2)

dj



sj
n
= 1 z di
n
1=1
/
= / 1
"2 n o
S di - 1 ( E d^r
1-1 "n" 1-1
                                                                     (3)
Where n is the number of precision checks on the instrument made during the
sampling quarter.  For example, n should be 6 or 7 if span checks are made
bi-weekly during a quarter.

     Calculate the 95 percent probability limits for precision using equations
4 and 5.

     Upper 95 Percent Probability Limit = dj + 1.96 Sj                (4)

     Lower 95 Percent Probability Limit = dj - 1.96 Sj                (5)

4.1.4.2  Single Analyzer Accuracy - Each organization,  at the end of each
sampling quarter, shall  calculate and report the percentage difference for
each audit concentration for each analyzer audited during the quarter.
Directions for calculations are given below (directions for reporting are
given in Section 4.1.6).

     Calculate and report the percentage difference (d-j)  for each audit
concentration using equation 1  where Y-j is the analyzer's indicated concen-
tration from the i-th audit check and X-j is the known concentration of the
audit gas used for the i-th audit check.
                                     44

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4.1.5  Calculations for Manual  Methods

4.1.5.1  Single Instrument Precision for TSP, Pb? and PMin»   Estimates of
precision for ambient air quality participate measurements are calculated from
results obtained from collocated samplers as described in section 4.1.2.3.
At the end of each sampling quarter, calculate and report a  precision
probability interval, using weekly results from the collocated samplers.
Directions for calculations are given below, and directions  for reporting
are given in Section 4.1.6.
     For the paired measurements obtained as described in sections 4.1.2.3(a)
and 4.1.2.3(6), calculate the percent difference (d-j)  using equation la,
where Yj is the concentration of pollutant measured by the duplicate sampler,
and X-j is the concentration measured by the sampler reporting air quality for
the site.  Calculate the quarterly average percent difference (dj), equation
2, standard deviation (Sj), equation 3, and upper and lower 95 percent
probability limts for precision (equations 6 and 7).
                                    x 100
                                                                 (la)
Upper 95 Percent Probability Limit - dj  + 1.96 Sj/

Lower 95 Percent Probability Limit - dj  - 1.96 Sj/
                                                                       (6)

                                                                       (7)
4.1.5.2  Single Instrument Accuracy for TSP and PMm - Each organization, at
the end of each sampling quarter, shall calculate and report the percentage
difference for each high-volume or PMjo sampler audited during the quarter.
Directions for calculation are given below and directions for reporting are
given in Section 4.1.6.

     For the flow rate audit described in Section 4.1.3.4, let X-j represent
the known flow rate and Yi represent the indicated flow rate.  Calculate the
percentage difference (d-j) using equation 1.

4.1.5.3  Single Instrument Sampling Accuracy for Pb - Each organization, at
the end of each sampling quarter, shall calculate and report the percentage
difference for each high-volume lead sampler audited during the quarter.
Directions for calculation are given in Section 4.1.5.2 and directions for
reporting are given in Section 4.1.6.

4.1.5.4  Single-Analysis-Day Accuracy for Pb - Each organization, at the
end of each sampling quarter, shall calculate and report the percentage
difference for each Pb analysis audit during the quarter.  Directions for
calculations are given below and directions for reporting are given in
Section 4.1.6.
                                     45

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     For each analysis audit for Pb described in Section 4.1.3.4(b), let X-j
represent the known value of the audit sample and Y-j  the indicated value of
Pb.  Calculate the percentage difference (d-j) for each audit at each concen-
tration level using equation 1.

4.1.6  Organization Reporting Requirements

       At the end of each sampling quarter, the organization must report
the following data assessment information:  (a) for automated analyzers -
precision probability limits from Section 4.1.4.1 and percentage differences
from Section 4.1.4.2, and (b) for manual methods - precision probability
limits from Section 4.1.5.1 and percentage differences from Sections 4.1.5.2,
4.1.5.3 and 4.1.5.4.  The precision and accuracy information for the entire
sampling quarter must be submitted with the air monitoring data.  All  data
used to calculate reported estimates of precision and accuracy including
span checks, collocated sampler and audit results must be made available to
the permit granting authority upon request.

4.2  Quality Assurance for Noncriteria Air Pollutants

     At the present time, there are no EPA regulations on quality assurance
for PSD monitoring of noncriteria air pollutants.  The following are EPA
recommendations for a minimum quality assurance program for noncriteria
pollutants.

4.2.1  Selection of Method

       Selection of the measurement method for noncriteria air pollutants
is extremely important.  A list of acceptable measurement methods for
noncriteria air pollutants is available and may be obtained by writing:
U.S. Environmental Protection Agency, Environmental Monitoring Systems
Laboratory, Quality Assurance Division (MD-77), Research Triangle Park,
North Carolina  27711. This list of acceptable methods will be revised at
least annually and be available from the above address.  Measurement methods
considered candidates for the noncriteria pollutant list should be brought
to the attention of EPA at the address given above.

4.2.2  Calibration

       Calibration procedures described in the acceptable methods should be
followed and a schedule for calibrations should be established.  In addition,
flow measurement devices used to measure sampling rate should be calibrated
and a schedule established for recalibration.  Calibration procedures for
several flow measurement devices (rotameter, critical orifice, mass flow
meter, and wet test meter) are described in Section 2.1.2 of reference 39.
All calibration procedures should be written and maintained up-to-date by a
document control system.  A description of one document control system that
has been found to be effective is discussed in Section 1.4.1 of reference 38.
                                     46

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4.2.3  Data Validation

       Measurement data of poor quality may be worse than  no  data  at  all.
Therefore, the monitoring organization should establish  data  validation
procedures and implement these procedures to invalidate  data  of  question-
able quality.  Examples of data validation procedures for  criteria pollu-
tants described in Section 2.0.9 of reference 39 may be  useful as  a guide
in establishing data validation procedures for noncriteria pollutants.

4.2.4  Standard and Split Samples
       Where possible, standard samples containing  the pollutant of interest
should be analyzed periodically during the analysis of collected samples.
This practice is useful in helping to determine if  the analytical  system is
in control.  Splitting samples with another laboratory is  quite  useful  in
determining if there are unidentified biases in the analytical system.
                                     47

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                      5.   METEOROLOGICAL MONITORING
5.1   Data Required

     The preconstruction review of proposed major emitting facilities will
require the use of meteorological  data.   It is  essential  that such  data be
representative of atmospheric dispersion conditions at  the source and at
locations where the source may have a significant impact  on air quality.
The representativeness of the data is dependent upon (a)  the proximity of
the meteorological monitoring site to the area  under consideration, (b) the
complexity of the topography of the area, (c) the exposure of the meteorolog-
ical sensors, and (d) the period of time during which the data are  collected,
More guidance for determining representativeness is presented in reference
42.

     A data base representative of the site should consist of at least the
following data:

     a.  hourly average wind speed and direction

     b.  hourly average atmospheric stability based on  Pasquill stability
         category or wind fluctuations (a ), or vertical  temperature
         gradient combined with wind speea

     c.  hourly surface temperature at standard height  for climatological
         comparisons and plume rise calculations

     d.  hourly precipitation amounts for climatological  comparisons.

     In addition, hourly average mixing heights may be  necessary for the
air quality impact analysis.  In most cases, this may be  limited to an
extrapolation of twice-daily radiosonde measurements routinely collected by
the National Weather Service (NWS).  Sections 5.2 and 6.1 contain specific
information on instrument exposure and specifications.

     Requirements for additional instrumentation and data will depend upon
the availability of information needed to assess the effects of pollutant
emissions on ambient air quality, soils, vegetation, and  visibility in the
vicinity of the proposed source.  The type, quantity, and format of the
required meteorological data will also be influenced by the input require-
ments of the dispersion modeling techniques used in the air quality analysis
Any application of dispersion modeling must be  consistent with the EPA
"Guideline on Air Quality Models" [14],  The guideline  makes specific
recommendations concerning air quality models  and data  bases.  It also
specifies those situations for which models, data, and  techniques other
than those recommended therein, may be applied.

     Site-specific data are always preferable to data collected off-site.
The availability of site-specific meteorological data permits relatively
detailed meteorological analyses and subsequent improvement of dispersion


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model estimates.  An important source of background information pertaining
to on-site meteorological  instrumentation is contained in an EPA workshop
report [43],  Off-site meteorological data may be used in lieu of site-
specific data only if it is agreed by source owner and permit granting
authority that the off-site data are reasonably representative of atmospheric
conditions in the area under consideration.  The off-site meteorological
data can sometimes be derived from routine measurements by NWS stations.
The data are available as  individual observations and in summarized form
from the National Climatic Data Center, Federal Building, Asheville, NC
28801.  On the other hand, if the nearest source of off-site data is con-
siderably removed from the area under consideration, and especially if
there are significant terrain features, urban areas, or large bodies of
water nearby, it may be necessary that the required meteorological  data be
site-specific.

     In some cases, it will be necessary that data be collected at more
than one site in order to  provide a reasonable representation of atmospheric
conditions over the entire area of concern.  Atmospheric conditions may
vary considerably over the area.  In some cases, (e.g., complex terrain)  it
will not be feasible to adequately monitor the entire meteorological field
of concern.  Then the only recourse is to site the stations in areas where
characteristic and significant airflow patterns are likely to be encountered.
In any event, one of the meteorological stations should be located so that
it represents atmospheric  conditions in the immediate vicinity of the
source.

     Although at least 1 year of meteorological data should be available, a
shorter period of record that conforms to the air quality monitoring period
of record discussed in Section 2.5 is acceptable when approved by the
permit granting authority.  If more than 1 year of data is available, it  is
recommended that such data be included in the analysis.  Such a multiyear
data base allows for more comprehensive consideration of variations in
meteorological conditions  that occur from year to year.  A 5-year period  of
record will usually yield  an adequate meteorological data base for considering
such year-to-year variations.

     In all cases, the meteorological data used must be of at least the
quality of data collected by the National Weather Service.  Desired features
of instrumentation for collecting meteorological data are discussed in
Section 6.1.

5.2  Exposure of Meteorological Instruments

     Measurements of most meteorological parameters are affected by the
exposure of the  sensor.  To obtain comparable observations at different
sites, the exposures must be similar.  Also, the exposure should be such
that the measured parameters provide a good representation of pollutant
transport and dispersion within the  area that the monitoring site is supposed
to represent.   For example, if wind  flow data over a fairly broad area are
desired, the wind sensors should be  away from the immediate influence of
trees, buildings, steep slopes, ridges, cliffs, or hollows.


                                     49

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     The standard exposure of wind  instruments  over level  open  terrain  is
10 meters above the ground.  Open terrain  is  defined as  an area where the
distance between the anemometer and any obstruction to the wind flow is at
least five times the height of the  obstruction.   Where a standard  exposure
is unobtainable at this height, the anemometer  should be installed at such
a height that its indications are reasonably  unaffected  by local obstructions
and represent as closely as possible what  the wind  at 10 meters would be in
the absence of the obstructions. Detailed guidance on assessing adverse
aerodynamic effects due to local obstructions is  contained in  reference 44.
In locating wind sensors in rough terrain  or  valley situations, it will  be
necessary to determine if local effects such  as channeling, slope  and
valley winds, etc., are important,  or whether the flow outside  those zones
of influence is to be measured.  If the analysis  concerns emissions from a
tall  stack, it may be desirable to  avoid the  local  influences.   On the
other hand, if pollution from low-level sources is  the main concern, the
local influences may be important.

     If the source emission point is substantially  above the standard
10-meter level for wind measurements, additional  wind measurements at the
height of the emission point and at plume  height  are desirable. Such
measurements are used to determine  the wind regime  in which the effluent
plume is transported away from the  source.  (The  wind speed and direction
50 to 100 meters or more above the  surface are  often considerably  different
than at the 10-meter level.)  An instrumented tower is the most common
means of obtaining meteorological measurements  at several  elevations in the
lower part of the atmospheric boundary layer.  For  wind  instruments mounted
on the side of a tower, precautions must be taken to ensure that the wind
measurements are not unduly influenced by  the tower. Turbulence in the
immediate wake of a tower (even a latticetype tower) can be severe. Thus,
depending on the supporting structure, wind measuring equipment should  be
mounted (e.g., on booms) at least two structure widths away from the structure,
and two systems mounted on opposite sides  of the  structure will sometimes
be necessary.  A wind instrument mounted on top of  a tower should  be mounted
at least one tower width above the  top.  If there is no  alternative to
mounting instruments on a stack, the increased  turbulence problem  [45],
must be explicitly resolved to the  satisfaction of  the permit  granting
authority.

     Atmospheric stability is another key  factor  in pollutant  dispersion
downwind of a source.  The stability category is  a  function of  static
stability (related to temperature change with height), convective  turbulence
(caused by heating of the air at ground level), and mechanical  turbulence
(a function of wind speed and surface roughness).  A procedure  for estima-
ting stability category is given by Turner [46] which requires  information
on solar elevation angle, cloud cover, ceiling  height, and wind speed.   The
hourly observations at NWS stations include cloud cover, ceiling height,
and wind speed.  Alternative procedures for estimating stability category
may be applied if representative data are  available. For example, stability
category estimates may be based upon horizontal wind direction  fluctuations
[47], or vertical gradients of temperature and  wind speed [48]. To obtain
                                     50

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a representative reading of the air temperature, the temperature sensor
should be protected from thermal  radiation from the sun,  sky,  earth,  and
any surrounding objects, and must be adequately ventilated.   Aspirated
radiation shields are designed to provide such protection.  (Note that
ambient temperature data are also commonly required for plume  rise estimates
used in dispersion model calculations.)

     Mixing height is another parameter that can be important  in some
cases.  Mixing height is the distance above the ground to which relatively
free vertical  mixing occurs in the atmosphere.  For estimating long-term
average concentrations, it is adequate to use a representative annual
average mixing height [49],  However, in many cases, and  especially for
estimates of short-term concentrations,  twice-daily or hourly  mixing  height
data are necessary.  Such data can sometimes be derived [49] from represen-
tative surface temperatures and twice-daily upper air soundings collected
by selected NWS stations.

     Precipitation collectors must be located so that obstructions do not
prevent the precipitation from falling into the collector opening or  force
precipitation into the opening.  Several collectors may be required for
adequate spatial resolution in complex topographic regimes.

     Final rule making entitled "Visibility Protection for Federal Class I
Areas," was published in the Federal Register on December 2, 1980.  The
regulations are applicable to 36 States listed in the action.   Although
these States are not required to establish visibility monitoring networks,
they should consult with the Federal Land Managers to determine monitoring
needs.  Paragraph 51.305 states that the SIP strategies "must  take into
account current and anticipated visibility monitoring research, the avail-
ability of appropriate monitoring techniques and such guidance as is  pro-
vided by the Agency."  Visibility definitions, monitoring methods, modeling
considerations and impact assessment approaches are among the  subjects of
three EPA reports: (1) "Protecting Visibility:  An EPA Report  to Congress"
[50], (2) "Interim Guidance for Visibility Monitoring" [51], and (3)  "Work-
book for Estimating Visibility Impairment" [52].  Also, since publication
of the final rule, the.National Park Service has established a visibility
monitoring system.  The States or permit granting authority should consider
these resources when handling visibility new source review questions.

     Additional information and guidance on siting and exposure of
meteorological instruments is contained in reference 53.
                                    51

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                      6.   METEOROLOGICAL INSTRUMENTATION


6.1   Specifications

     Meteorological instrumentation used for PSD monitoring must yield
reasonably accurate and precise data.   Accuracies and allowable errors are
expressed in this section as absolute  values for digital  systems; errors in
analog systems may be 50  percent greater.  For example,  an allowable error
expressed as 5 percent means the recorded value should be within _+5 percent
of the true value for digital  systems, and +7.5 percent  for analog systems.
Records should be dated,  and should be accurate to within 10 minutes.  Wind
speed and direction (or vector components) should be recorded on a digital
data logging system at intervals not to exceed 60 seconds for a given
variable; data recorded on continuous  strip recorders at intervals not
exceeding 60 seconds may  be used as backup.  These specifications apply to
the meteorological instruments used to gather the site specific data that
will accompany a PSD permit application.  When the use of existing represen-
tative meteorological data is approved by the permit granting authority,
the instrumentation should meet, as a  minimum, NWS standards [54-55].

6.1.1  Wind Systems (horizontal wind)

       Wind direction and wind speed systems should exhibit a starting
threshold of less than 0.5 meter per second (m/s) wind speed (at 10 degrees
deflection for direction  vanes).  Wind speed systems should be accurate
above the starting threshold to within 0.25 m/s at speeds equal to or less
than 5 m/s.  At higher speeds, the error should not exceed 5 percent of the
observed speed (maximum error not to exceed 2.5 m/s).  The damping ratio of
the wind vane should be between 0.4 and 0.65 and the distance constant
should not exceed 5 m.  Wind direction system errors should not exceed 5
degrees, including sensor orientation  errors.  Wind vane orientation
procedures should be documented.

6,1.2  Wind Systems (vertical  wind)

       In complex terrain, downwash of plumes due to significant terrain
relief may pose a problem.  If such a  problem potentially exists, it may be
necessary to measure the vertical component of the wind at the proposed
site, and as close as possible to stack height.  The starting threshold for
the vertical wind speed component should be less than 0.25 m/s.  Required
accuracy for the vertical wind speed component is as specified in Section
6.1.1 for horizontal speeds.

6.1.3  Wind Fluctuations

       Determination of the on-site standard deviation of wind fluctuations,
or derived standard deviations of cross-plume concentrations may be necessary
if dispersion parameters  are being developed for use at a specific site.  Since
the analytical framework  within which  such wind fluctuations measurements/
                                      52

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statistics are to be incorporated is expected to be unique or applied on a
case-by-case basis, approval  by the permit granting authority is required
and no general requirements regarding specifications are outlined in this
guideline.  Considerable care is required in the selection of wind instru-
ments and data logging systems, especially in the choice of sampling and
averaging times.  Thus, response characteristics of wind sensors are
especially critical [56,57].   Owners or operators designing programs incor-
porating these capabilities should submit a statement from a qualified
consultant identifying the adequacy of such wind system(s) within the
context of the overall PSD ambient monitoring program.

6.1.4  Vertical Temperature Difference

       Errors in measured temperature difference should not exceed 0.003
°C/m.

6.1.5  Temperature

       Errors in temperatures should not exceed 0.5°C if fog formation,
icing, etc., due to water spray or water vapor emitted from the facility
may be a problem.  Otherwise, errors should not exceed 1.0°C.

6.1.6  Humidity

       Atmospheric humidity can be measured and expressed in several ways.
If the permit granting authority determines that a significant potential
exists for fog formation, icing, etc., due to effluents from the proposed
facility, error in the selected measurement technique should not exceed an
equivalent dewpoint temperature error of 0.5°C.  Otherwise, errors in
equivalent dewpoint temperature should not exceed 1.5°C over a dewpoint
range of -30°C to +30°C.

6.1.7  Radiation - Solar and Terrestrial
       The determination of Pasquill stability class may be based on whether
the solar radiation is termed strong, moderate, or slight.  Stability class
can be determined from sun elevation and the presence, height, and amount
of clouds [46], or by using a pyranometer and/or net radiometer during the
daytime and a net radiometer at night.  Such radiation-to-stability relation-
ships are expected to be site-specific, and the responsibility for demon-
strating their accuracy lies with the permit applicant.  General accuracy
for pyranometers and net radiometers used in a PSD monitoring network is
expected to be +5 percent.

6.1.8  Mixing Height

       Mixing height data may be derived from NWS upper air data.  If
available data are determined to be inappropriate by the permit granting
authority, such data may be obtained on-site by the permit applicant [58]
                                     53

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The instrument system to be used is not specified in this guideline,  but
its precision and resolution should not exceed the limits associated  with
NWS radiosonde systems [54,55].

6.1.9  Precipitation

       A recording precipitation collector should have a resolution of 0.25
mm (0.01 inches) liquid precipitation per hour at precipitation rates up to
7.6 cm/hour.  Accuracy should be within 10 percent of the recorded value. A
heated system should be used to assure proper measurement of frozen precipi-
tation.  A suitable windscreen should be used.

6.1.10  Visibility

        Visibility can be measured within 5 percent of true over visual
ranges of about 80 meters to 3 km with available transmissometers. Estimates
can be based upon very short path lengths using other types of equipment
such as nephelometers [59].  At this time, the combined use of a multi-
wavelength telephotometer, integrating nephelometer and particulate monitor,
together with color photography, should prove most helpful  in documenting
baseline visibility related parameters.  These as well as other components
of a visibility monitoring program, are discussed in reference 51. Reference
50 also contains much background information.
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               7.  QUALITY ASSURANCE FOR METEOROLOGICAL DATA


     All  equipment should receive an appropriate examination and calibration
prior to initial  installation to assure the acquisition of the maximum
amount of usable  data within the error limits specified herein.  Inspection,
servicing, and calibration of equipment must be scheduled throughout the
measurement program at appropriate intervals to assure at least 90 percent
data retrieval for each variable measured at sites where continuous air
quality monitors  are being operated.  At remote sites, data retrieval  for
measured variables should not fall below 80 percent.   In addition, the
joint frequency for the recovery of wind and stability data should not fall
below 90 percent  on an annual basis; missing data periods must not show
marked correlation with the various meteorological  cycles.

     Calibration  of systems should be accomplished no less frequently than
once every 6 months.  In corrosive or dusty areas, the interval should be
reduced to assure adequate and valid data acquisition.

     If satisfactory calibration of a measuring system can be provided only
by the manufacturer or in special laboratories, such  as wind-tunnel facilities,
arrangements should be made for such calibrations prior to acquisition of
the equipment.  A parts inventory should be maintained at a readily accessible
location to minimize delays in restoring operations after system failures.

     An independent meteorological audit (by other than one who conducts
the routine calibration and operation of the network) should be performed
to provide an on-site calibration of instruments as well as an evaluation
of (a) the network installation, (b) inspection, maintenance, and calibra-
tion procedures,  and logging thereof, (c) data reduction procedures, including
spot checking of  data, and (d) data logging and tabulation procedures.  The
on-site visit (requiring as little as 1 day in many cases) should be made
within 60 days after the network is first in full operation, and a written
audit/evaluation  should be provided to the owner.  This report should be
retained by the owner.  Any problems should be corrected and duly noted as
to action taken in an addendum to the audit report.  A reproducible copy of
the audit report  and the addendum should be furnished with the source
construction permit application.

     Such independent meteorological audit-evaluations should be performed
about each 6 months.  The last such inspection should be made no more than
30 days prior to  the termination of the measurement program, and while the
measurement operation is in progress.

     The 1983 publication "Quality Assurance Handbook for Air Pollution
Measurement Systems:  Volume IV.  Meteorological Measurements" [60] should
be consulted for  more information.  Major sections in this volume address
(1) quality assurance of the measurement process, (2) methods for judging
the suitability of sensor siting, and (3) meteorological data validation.
                                     55

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                             8.  DATA REPORTING
8.1  Air Quality Data Reporting

     A summary of the air quality data, the raw air quality data, and the
quality assurance data discussed in  Section 4.1.6  must be submitted to
the permit granting authority at the time of submittal of the PSD application.
There should be a prior agreement between the source and the permit granting
authority as to whether the raw data should be submitted in addition to a
summary of the data.  Some sources may also desire to submit data periodically
to the permit granting authority for review to identify any problems in the
data as they occur.  Note that this is not a requirement.  The applicant
and the permit granting authority should have a prior agreement as to the
format and procedure for the data submission.  The air quality data should
preferably be submitted in SAROAD format and in a machine readable form.  A
printout of the contents of the tape or cards should also be included.  All
raw data not previously submitted (i.e., calibration data, flow rates,
etc.) should be retained for 3 years and submitted upon request to the
permit granting authority.

     For continuous analyzers, at least 80 percent of the individual hourly
values should be reported by the source in any sampling period.  For manual
methods (TSP and particulate pollutants), 80 percent of the individual
24-hour values should be reported in any sampling period.  This capture
rate is important because of the short duration of a PSD monitoring program.
In addition, there should not be a correlation between missing data periods
and expected highest concentrations.

8.2  Meteorological Data Format and Reporting

     Because of the different data requirements for different types of
analyses that might be used to evaluate various facilities, there is no
fixed format that applies to all data sets.  However, a generalization can
be made:  all meteorological  parameters must be collated in chronological
order and tabulated according the observation time, and be furnished to the
permit granting authority upon request.  All meteorological variables that
have a SAROAD parameter code should be submitted in SAROAD format.  All
units should be in the SI system (International  System of Units)  [61]. All
input data (in the format required by the analytical  procedures selected)
used in, and all  results of,  the air quality analyses must be furnished to
the permit granting authority upon request.
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                   APPENDIX A






PROCEDURES TO DETERMINE IF MONITORING DATA WILL



       BE REQUIRED FOR A PSD APPLICATION

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                               1.   INTRODUCTION


     This appendix has been included in this  guideline to aid  both the
reviewing authorities and the source applicants  in determining if monitoring
data will or will  not be required  under PSD.   The  major considerations
leading to a monitoring data decision have been  simplified for presentation
in this appendix.   This discussion represents the  Federal  requirements and
the minimum State  program requirements.  It is important to identify the
reviewing authority,  whether it be the local  or  State air pollution control
agency, or the Regional Office of  EPA for the final  requirements.  For a
complete discussion on the complex PSD issues, the reader is referred to
the PSD regulations and the preamble discussion  [5,6].

                2.  PSD PERMIT APPLICATION PROCEDURES

     Figure A-l shows a simplified organizational  overview of  the proce-
dures to be followed  in the preparation of a  PSD permit application.
Figure A-l shows that these procedures are divided into seven  parts.  This
division is only for  illustrative  purposes within  this appendix and is
intended only to separate the complex procedures into distinct subparts.
Within the Part 1-Source Applicability Determination, both candidate new
and modified major sources are reviewed to see if  PSD review will apply.
The Part 2-Pollutant  Applicability Determination shows those pollutants
emitted from subject  sources that  may or may  not be exempted from further
analysis.  The Part 3-BACT Analysis is to ensure the application of best
available control  technology (BACT) on subject pollutants.  Air quality
analysis covered in Part 4 includes both modeling  and monitoring data
considerations for certain BACT pollutants.  The Part 5-Source Impact
Analysis is to demonstrate that the proposed  emissions would not cause or
contribute to a violation of any NAAQS or PSD increment.  The  Part 6-
Additional Impact  Analysis is to ensure that  the proposed emissions increases
would not impair visibility, or impact on soils  and vegetation.  Finally,
Part 7 represents  the complete PSD application which transfers to the
permit granting authority the results of all  the analysis from the first
six parts.  Normally, the source applicant will  supply all the information
including the BACT and air quality analyses to make the necessary determi-
nations.  Each of  these seven parts is discussed below in Sections 2.1-2.7.
Section 3 contains flow diagrams and discussion  of the first four parts
that pertain to the decision whether monitoring  data will  or will not be
requi red.

2.1  Part 1 - Source Applicability Determination

     The first step in the PSD program is to  determine if a proposed new
or modified source is subject to the PSD regulations.  The first test for
PSD applicability  is  that the proposed construction must involve a major
stationary source.  Thus, the candidate construction must either be a
proposed new major stationary source or involve the modification of an
existing major stationary source.   The criteria in determining whether
                                     A-l

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 Part 1 - Source Applicability Determination
                     \
Part 2 - Pollutant Applicability Determination
                     I
           Part 3 - BACT Analysis
    Part 4 - Ambient Air Quality Analysis
       Part 5 - Source Impact Analysis
      Part 6 - Additional Impact Analysis
      Part 7 - Complete PSD Application
Figure A-1. Simplified procedures for the preparation of a PSO permit application.
                       A-2

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the affected source is sufficiently large (in terms  of emissions)  to be a
new major stationary source or major modification  is based on  consideration
of its potential  to emit at rates exceeding certain  threshold  values.
Potential to emit is the capability at maximum design capacity to  emit a
pollutant after the application of all required air  pollution  control
equipment, taking into account all federally enforceable requirements
restricting the type or amount of source operation.   A major modification
is generally a physical change in or a change in the method of operation of
a major stationary source which would result in a  significant  net  emissions
increase for any regulated pollutant.  (There are  several  changes  that are
exempted from being considered a major modification.) Also, the proposed
source or modification must locate in a PSD area—an area  designated as
"attainment" or "unclassifiable."  If the proposed source  or modification
would meet certain tests and commence construction in a continuous fashion
at the proposed site within a reasonable time, a PSD permit under  the
August 7, 1980 regulations would not be necessary.  Lastly, there  are
specific new sources and modifications that are exempted from  PSD  review.
All of the above considerations are explained in more detail in Section 3
of this appendix.

     If it is determined that a new source or modification is  subject to
the PSD regulations, then one must proceed to the  Part 2-Pollutant
Applicability Determination in order to learn how  the pollutant-specific
requirements of PSD may apply.

2.2  Part 2 - Pollutant Applicability Determination

      If a source applicant has determined that a  proposed new source or
modification would be subject to the PSD requirements, then the applicant
must assess whether the pollutants the project would emit  are  subject to
PSD.  If a new major stationary source emits pollutants for which  the area
it locates in is designated nonattainment, then the  source is  exempt from
PSD review for those pollutants.  These sources must, however, meet the
applicable requirements of new source review (NSR) for each nonattainment
pollutant.  If a major construction proposed for a PSD area involves only
changes for nonattainment pollutants, then the source is not subject to
PSD.  These sources must meet the appropriate nonattainment NSR under the
SIP for the pollutant.  Once the question of NSR jurisdiction  is resolved,
then the PSD review applies to significant emissions increases of  regulated
ai r pollutants.

     Specific numerical cutoffs which define what  emissions increases are
"significant" are shown in Table A-l.  These emissions rates will  be used
for pollutants to be emitted from a PSD source unless the  new  source or
modification is to be located within 10 km of a Class I area [1],  For these
situations, the proposed source or modification must be prepared to demonstrate
that it would not have a significant impact with respect to a  Class I area.
A Class I significant impact is defined as one microgram per cubic meter
(ug/m3 or more for a 24-hour average.  Further details on  how  the  significant
emission rates in Table A-l were derived may be found in the preamble
discussion of the PSD regulations [5].


                                     A-3

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               TABLE A-l.  SIGNIFICANT EMISSIONS RATES
                            f  < s    -  • •    - -'  ; •  '
             Pollutant                   Emissions Rate (tons/year)

Carbon monoxide                                  100
Nitrogen oxides                                   40
Sulfur dioxide                                    40
Particulate Matter                                25 (TSP)
Particulate Matter                                15 (PMio)
Ozone (volatile organic compounds)                40
Lead                                               0.6
Asbestos                                           0.007
Beryllium                                          0.0004
Mercury                                            0.1
Vinyl  chloride                                     1.0
Fluorides                                          3
Sulfuric acid mist                                 7
Total  reduced sulfur (including H2S)              10
Reduced sulfur (including t^S)                    10
Hydrogen sulfide                                  10
                                 A-4

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     If the emissions from a new source will  be significant, or if the net
emissions increase from a proposed modification will  be significant, then
one must proceed to the Part 3-BACT Analysis  for these pollutants.

2.3  Part 3 - BACT Analysis

     Any major stationary source or major modification subject to PSD must
conduct an analysis to ensure application of  best available control  technology
(BACT) for all applicable pollutants.  During each analysis, which will  be
done on a case-by-case basis, the reviewing authority will  evaluate the
energy, environmental, economic, and other costs associated with each
alternative technology.  The reviewing authority will then  specify an
emissions limitation for the source that reflects the maximum degree of
reduction achievable with all these concerns  in mind  for each pollutant
regulated under the Act.  In no event can an  emission limitation be required
which would be less stringent than any applicable standard  of performance
under 40 CFR Parts 60 and 61.

     After the BACT determination, the source must then investigate the
need for each pollutant subject to BACT (BACT pollutant) to also undergo
the remaining analyses for this pollutant.

2.4  Part 4 - Ambient Air Quality Analysis

     Each application by a PSD source or modification must  contain an air
quality analysis for each BACT pollutant to demonstrate that its new pollutant
emissions would not violate either the applicable NAAQS or  the applicable
PSD increment.  This analysis ensures that the existing air quality is
better than that required by national standards and that baseline air
quality is not degraded beyond the applicable PSD increment.  Two narrow
exemptions to this requirement are specified  in the regulations and involve
certain existing sources with low BACT emissions and  sources of temporary
emissions meeting certain criteria.

     In making the above determinations, many PSD sources must first assess
the existing air quality for each applicable  air pollutant  that it emits in
the affected area.  The requirement to monitor existing air quality may  not
apply to (a) pollutants for which the new emissions proposed by the applicant
would cause impacts less than the significant monitoring concentrations
(Table A-2), or (b), situations where the background  concentration of the
pollutant is below the significant monitoring values.  This exemption
should not be used when there is an apparent  threat to an applicable PSD
increment or NAAQS based on modeling alone or when there is a question of
adverse impact on a Class I area.  When monitoring data are required, the
applicant must provide ambient montioring data that represent air quality
levels in the year's period preceding the PSD application.   Where existing
data are not judged representative or adequate, then  the applicant must
conduct its own monitoring program.  Typically, monitoring  data are used
by applicants to support or extend the assessment made with air quality
dispersion modeling.
                                    A-5

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            TABLE  A-2.   SIGNIFICANT MONITORING  CONCENTRATIONS
           Pollutant
Air Quality Concentration (ug/m3)
   and Averaging Time
 Carbon  monoxide
 Nitrogen  dioxide
 Sulfur  dioxide
 Particulate Matter
 Particulate Matter
 Ozone
 Lead
 Asbestos
 Beryl lium
 Mercury
 Vinyl  chloride
 Fluorides
 Sulfuric acid mist
 Total  reduced sulfur (including  H2S)
 Reduced sulfur  (including
 Hydrogen sulfide
     575  (8-hour)
      14  (Annual)
      13  (24-hour)
      10  (24-hour) for TSP
      10  (24-hour) for
     a
       0.1  (3-month)
     b
       0.001  (24-hour)
       0.25  (24-hour)
      15  (24-hour)
       0.25  (24-hour)
     b
     c
     c
       0.2 (1-hour)
dNo specific air quality concentration for ozone is  prescribed.   Exemptions
 are granted when a source's VOC emissions are  100  tons/year.
bNo acceptable monitoring techniques available at this  time.   Therefore,
 monitoring is not required until  acceptable techniques are available.
GNo acceptable monitoring techniques available at this  time.   However,
 techniques are expected to be available shortly.
                                   A-6

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     In addition to the above discussion,  EPA in general  intends to limit
the application of air quality models to a downwind distance of 50 kilometers.
This is because dispersion parameters commonly in use are based on experiments
relatively close to sources,  and extending these parameters  to long downwind
distances results in great uncertainty as  to accuracy of  the model estimates
at such distances.  EPA does  not intend to analyze the impact of a source
beyond the point where the concentrations  from the source fall below certain
levels (generally based on Class I increments) shown in Table A-3.  However,
since the 1977 Clean Air Act  Amendments provide special concern for Class I
areas, any reasonably expected impacts for these areas must  be considered
irrespective of the 50 km limitation on the above significant values.*

2.5  Part 5 - Source Impact Analysis

     The proposed source or modification must demonstrate that significant
net emissions increases (including secondary emissions and fugitive emissions),
would not cause or contribute to air pollution in the violation of any
NAAQS or any applicable maximum allowable  increase over the  baseline
concentration in any area.

2.6  Part 6 - Additional Impact Analysis

     An applicant is also required to analyze whether its proposed emissions
increases would impair visibility, or impact on soils or  vegetation.  Not
only must the applicant look  at the direct effect of source  emissions on
these resources, but it also  must consider the impacts from  general commercial,
residential, industrial and other growth associated with  the proposed
source or modification.

2.7  Part 7 - File Complete PSD Application

     After completion of the  proceeding analyses, the source may submit a
PSD application to the permit granting authority.  The application, after
being judged complete and being reviewed for proper determination of appli-
cability, BACT, and air quality impacts, must undergo adequate
*It should be noted that there are three separate and distinct sets  of
values which are considered "significant" within the PSD program:

     (a)  Significant emissions rates;
     (b)  Significant monitoring concentrations; and
     (c)  Significant ambient impacts (including the specific significant
          Class I area impacts).

As pointed out, each set of values has  a different application, and
therefore, this guideline has been worded to clarify the appropriate
values to be used while assessing the need to collect monitoring data.
                                    A-7

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           TABLE A-3.  SIGNIFICANT AMBIENT AIR QUALITY IMPACTS
              _ Averaging Time

Pollutant     Annual _ 24-Hour _ 8-Hour _ 3-Hour _ 1 Hour


  S02         1 ug/m3     5 ug/m3        --        25 ug/m3


  PM10        1 ug/m3     5 ug/m3


  N02         1 ug/m3


  CO             —          «        0.5 mg/m3      —        2 mg/m
NOTE:  This table does not apply to Class I areas.  A significant impact
       for Class I areas is 1 ug/m3 on a 24-hour basis for PMin and SOo.
                                   A-8

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public participation.  The regulations solicit and encourage participation
by the general  public, industry, and other affected persons impacted by the
proposed major stationary source or major modification.   Specific public
notice requirements, including a public comment period and the opportunity
for a public hearing must be met before the PSD review agency takes final
action on a PSD application.  The public notice must indicate whether the
reviewing authority has proposed approval, denial, or conditional approval
of the proposed major source or major modification.  Consideration is given
to all comments received provided they are relevant to the scope of the
review.

     The source shall also submit all information necessary to perform any
analysis in Parts 1-6 above or make any determinations required in Parts
1-6.  Such information shall include (a) a description of the nature,
location, design capacity, and typical operating schedule of the proposed
source or modification, including specifications and drawings showing its
design and plant layout, (b) a detailed schedule for construction of the
proposed source or modification, and (c) a detailed description as to what
system of continuous emission reduction is planned for the proposed source or
modification, emission estimates, and any other information necessary to
determine that best available control technology would be applied.  The
proposed source or modification shall also provide information on (a) the
air quality impact of the proposed source or modification, including meteoro-
logical and topographical data necessary to estimate such impact, and (b)
the air quality impacts, and the nature and extent of any or all  general
commercial, residential, industrial, and other growth which has occurred
since August 7, 1977 in any area the proposed source or  modification would
affect.
                                     A-9

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               3.  DECISIONS FOR MONITORING DATA REQUIREMENTS

      Figure A-1  and the discussion that followed in Section 2  provided  an
overview of the various activities relating to a PSD permit application.
This section will go into more detail  on those activities  that  need  to be
considered in deciding if air quality  monitoring data will be  required.

     It should be noted that the procedures described in this  appendix do
not include any details on how the modeling analyses are to be  conducted
but only indicate at what points (boxes) the results of such analyses  are
necessary.  Also, while these procedures lead to a determination  of  when
air quality monitoring is likely to be required, they do not lead to a
decision as to when meteorological monitoring is necessary (for model
input). Guidance on the requirements and procedures for conducting modeling
analyses is contained in reference 14.  Section 5 of this  guideline  describes
general meteorological monitoring requirements, and reference  62  also
provides further guidance on this subject.

     Figures A-2 and A-3 show various  steps that must be made  for a  proposed
PSD source or modification in order to assess how the monitoring  data
requirement might apply.  The decisions in  these flow diagrams  must  be
applied separately for each regulated  pollutant that would be  emitted  from
a proposed source or modification.  Boxes 1-14 apply to Figure  A-2 and
boxes 15-29 apply to Figure A-3

Box 1.  Is proposed source a major stationary source or major  modification
        locating in a PSD area?

     A major stationary source is defined as any one of 28 source categories
(Table A-4) which emits, or has the potential to emit, 100 tons per  year or
more of any pollutant regulated under  the Act.  In addition, the  definition
includes any other stationary source which  emits, or has the potential to
emit, 250 tons per year or more of any regulated pollutant.   Finally,  major
stationary source also means any physical change occurring at  a stationary
source (which prior to the change is not major) if the change  by  itself
would be major.  That is, the change itself would result in  an  equivalent
stationary source which would emit 100 tons per year or more  for  any pollutant
regulated under the Act for any one of the 28 source categories (Table
A-4), or 250 tons per year for any other stationary source.  The  pollutants
regulated under the Act were shown in  Part  2-Pollutant Applicability
Determination.

     A stationary source generally includes all pollutant-emitting activities
which belong to the same industrial grouping, are located  on  contiguous or
adjacent properties, and are under common control.  Pollutant  activities
which belong to the same major group as defined in a standard  industrial
classification scheme developed by the Office of Management  and Budget are
considered part of the same industrial grouping.

     The rest of the PSD size applicability for proposed  new stationary
sources is simply that the candidate source would be a major  stationary


                                     A-10

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                              1.  Is proposed source         \
                                 a major stationary source or \  J^Q
                                 4 major modification locating  /     ^
                                 in a PSD area?              /        /2.
                                                                No PSD
                                                                permit needed/
                                                 Part 1 -
                                                 Source Applicability
                                                 Determination
   YES
No further PSD
analysts for
that pollutant
                                          NO
3.  Is construction proposed
   for an area which is designated'
   nonattainment area for the    /  	
   regulated pollutant? *     /  13.
                                                                                                         J
                                              Is proposed source
                                              or modification within
                                              10 km of a Class I area?/
                                                            YES
                                                                   Class I area
                                                                   screening procedure
                                                                               7.  More refined model
                                                                                  (optional).  Note:  Mav
                                                                                  require gathering of
                                                                                  meteorological data.
  10.  No further analysis
      for that pollutant
                Are new emissions or net
                emissions increase of the
                regulated pollutant > Table

                                                           /8.  Will the proposed source^
                                                          I/     or modification impact
                                                           \    on a Class I area?
YES
                                                                                                          Part 2 -
                                                                                                          Pollutant Applicability
                                                                                                          Determination
                                                 YES
                                              11.  Is proposed construction a
                                                  relocation ot a portable
                                                  facility with previous permit? l
                                                                                       NO
                    Are there potential impacts
                    on a Class I area, or areas
                    of known increment  violation?
                                                          , YES
                                                                       14. Apply BACT
                                                                                                    Part 3 -
                                                                                                    BACT Analysis
    ' Procedures are to be repeated for
     all regulated pollutants  which would
     be emitted by the proposed construction.
                                      c
                                      (
Part 4
- Ambient Air Quality Analysis

Part 5
Part 6
- Source Impact Analysis
- Additional Impact Analysis

Part 7
• Complete PSD Application
          Figure A-2.  Procedures used to determine the monitoring data requirement.
                                                         A-ll

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                                                                 Part 1 - Source Applicability Determination
                                                                 Part 2 - Pollutant AppKcabltty Determination
                                                                                 I
                                                                 Part 3 - BACT Analysis
                                                              NO,
                                  YES,
                                       '16.  wa the proposed    X,
                              15. Are the allowable emissions or the
                                 net emissions increase temporary,
                                 impacting no Class I area, or impacting
                                 no area where  the PSD increment
                                 is violated?
                                                                                                             . YES
                           Are VOC    N
                           emiuiom
                           < Table A-2? ,
                                            source or modification /
                                            emil VOQ           /
  . NO
     18. Is there an apparent threat\
NO/     to the NAAQS, or is there
         a potential advene impact
         on a Class I area?
                                  YES
I 19.  WM proposed source or
     modification perform post-
     approval monitoring in  feu
     of preconstruction monitoring
     data?
                                         20.  Estimate existing air quality.
                                             Note: May require gathering
                                             of meteorological data.
                                21.  Estimate air quality impacts of
                                    proposed construction.
                                    • Use screening procedure
                                      or more refined model
                                    • Use "good engineering practice*
                                    • Consider 50 ton/ year exemption
                                                                                         22. Is the existing air
                                                                                             quality < Table A-2?
                                                                          , YES
                                                                NO
                               21 Are the air quatty\_YES_
                                   impacts < Table A-2? /
  YES,
25.  Are proposed emissionsX NO
 a criteria pollulant or VOC?/~~~
                                                                                                   34.  Is there an apparent threat to \
                                                                                                       the PSD increments or NAAQS. \YE5
                                                                                                       or is there a potential adverse  /
                                                                                                       impact on a Class I area?      /
                                                                 NO
                                 26.  Is there an approved
                                     monitoring technique
                                     available?
                          27. Preconstruction monitoring data required.
                              •  Use representative air quality data
                              •  Monitor (source specific)
                                  28.  No preconstruction
                                      monitoring data required
                                                       29.  Preconstruction monitoring
                                                           data may be required
                                                                                               Part 4-
                                                                                               Ambient
                                                                                               Air Quality
                                                                                               Analysis
                                                               G
                                                               C
                                                                  Part S - Source impact Analysis
                           Part 6- Additional Impact Analysis
                                                                  Part 7- Complete PSD Application
                                        FIGURE A-l  PROCEDURES USED TO DETERMINE THE MONITORING DATA REQUIREMENT.
                                                                             A-l 2

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                 TABLE A-4.   MAJOR STATIONARY  SOURCES
1.  Fossil-fuel  fired steam electric plants of more than 250,000,000
     British thermal  units per hour heat input
2.  Coal  cleaning plants (with thermal  dryers)
3.  Kraft pulp mills
4.  Portland cement plants
5.  Primary zinc smelters
6.  Iron  and steel  mill  plants
7.  Primary aluminum  ore reduction plants
8.  Primary copper smelters
9.  Municipal incinerators capable of charging more than 250 tons  of
     refuse per day
10. Hydrofluoric acid plants
11. Sulfuric acid plants
12. Nitric acid plants
13. Petroleum refineries
14. Lime  plants
15. Phosphate rock processing plants
16. Coke  oven batteries
17. Sulfur recovery plants
18. Carbon black plants  (furnace process)
19. Primary lead smelters
20. Fuel  conversion plants
21. Sintering plants
22. Secondary metal production plants
23. Chemical process  plants
24. Fossil-fuel  boilers  (or combinations thereof)  totaling of mere than
      250,000,000 British thermal  units per hour heat  imput
25. Petroleum storage and transfer units with a total  storage capacity
    exceeding 300,000 barrels
26. Taconite ore processing plants
27. Glass fiber processing plants
28. Charcoal production  plants
                                 A-13

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source in terms of its potential  to emit.   The applicability rules  for
determining whether a major modification would occur are more complex.

     A "major modification" is generally a physical  change in or a  change
in the method of operation of a major stationary source  which would result
in a significant net emissions increase in the emissions of any regulated
pollutant.  In determining if a proposed increase would  cause a significant
net increase to occur, several detailed calculations must be performed.
First, the source owner must quantify the  amount of  the  proposed emissions
increase.  This amount will generally be the potential to emit of the new
or modified unit.  Second, the owner must  document and quantify all emissions
increases and decreases that have occurred or will occur contemporaneously
(generally within the past five years) and have not  been evaluated  as part
of a PSD review.  The value of each contemporaneous  decrease and increase
is generally determined by subtracting the old level of  actual  emissions
from the new or revised one.  Third, the proposed emissions increase and
the unreviewed contemporaneous changes must then be  totalled.  Finally,  if
there is a resultant net emissions increase that is  larger than values
specified in Table A-l, the modification is major and subject to PSD review.

     Certain changes are exempted from the definition of major modification.
These include: (a) routine maintenance, repair and replacement; (b) use  of
an alternative fuel or raw material by revision of an order under sections
2(a) and (b) of the Energy Supply and Environmental  Coordination Action  of
1974 (or any superseding legislation); (c) use of an alternative fuel by
reason of an order or rule under section 125 of the  Clean Air Act;  (d) use
of an alternative fuel at a steam generating unit to the extent it  is
generated from municipal solid waste; (e)  use of an  alternative fuel or  raw
material which the source was capable of accommodating;  before January 6,
1975 or which the source is approved to use under any permit issued under
40 CFR 52.21, or under regulations approved pursuant to  40 CFR 51.24; and
(f) an increase in the hours of operation, or the production rate.   The
last two exemptions, (e) and  (f), can be used only if the corresponding
change is not prohibited by certain permit conditions established after
January 6, 1975.

     If the size of a proposed source or modification thus qualifies as
major, its prospective location or existing location must also qualify as a
PSD area, in order for PSD review to apply.  A PSD area  is one formally
designated by the state as "attainment" or "unclassifiable" for any pollutant
for which a national ambient  air quality standard exists.  This geographic
applicability test generally does not take into account  what new pollutant
emissions caused the construction to be major.  It looks simply at  whether
the source is major for any pollutant and will be located in a PSD  area.
The one exception is that  if  a major stationary source emits only non-
attainment pollutants, then no PSD review would apply.

     If a proposed source  or  modification would be subject to PSD review
based on size, location, and  pollutants emitted, it still may escape the
PSD review requirements under certain grandfather provisions under 40 CFR
                                    A-14

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52.21(1).  For example,  a proposed source or modification that  was  not
subject to the 1978 PSD  rules and had  received  all  necessary Federal,  State
and local air permits before August 7, 1980, would  not be subject to the
1980 regulations.  (See  the PSD regulations  for other exemptions.)

     Finally, the PSD regulations contain some  specific exemptions  for some
forms of source construction.  The requirements of  the PSD regulations do
not apply to any major stationary source or  major modification  that is (a)
a nonprofit health or educational institution (only if such exemption  is
requested by the governor), or (b) a portable source which has  already
received a PSD permit and proposes relocation,  or the source or modification
would be a major stationary source or  major  modification only if fugutive
emissions, to the extent quantifiable, are considered in calculating the
potential to emit of the stationary source or modification and  the  source
does not belong to any of the categories listed in  Table A-4.

Box 2.  No PSD permit needed.

     If the source has met the appropriate deadlines for construction; and
is not a major stationary source, a major modification, is not  located in a
PSD area, or is not subject to the specific  exemptions mentioned above, the
PSD program is not applicable, and therefore, no PSD permit is  needed.

Box 3.  Is construction  proposed for an area which  is designated
        nonattainment area for the regulated pollutant?

     If the project is a major stationary source or a major modification,
the prospective location must also qualify as a PSD area in order for the
PSD review to apply.  A PSD area is defined  as  an area formally designated
by the State as "attainment" or "unclassifiable" for any pollutant  for
which a NAAQS exists.  An area not classified as either "attainment" or
"unclassifiable" would be classified as "nonattainment".  If the proposed
construction is in a nonattainment area for  any pollutant, proceed  to box 4
for that pollutant; for  all other regulated  pollutants, proceed to  box 5.

Box 4.  No further PSD analysis for that pollutant.

     If the proposed major stationary  source or major modification  will
emit pollutants from an  area that has  been designated as "nonattainment",
then the proposed source or modification is  exempt  from further PSD review
for only those pollutants.  However, the proposed source or modification
must meet the applicable preconstruction requirements for each  nonattainment
pollutant.  (See 40 CFR  51.18 and 40 CFR 52.24.)

     The pollutant applicability determination  would be continued for  all
other regulated pollutants (except nonattainment pollutants) emitted by a
proposed major stationary source or major modification by proceeding to box 5,
                                    A-15

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Box 5.  Is proposed source or modification within 10 km of a Class  I
        area?

     The PSD regulations [40 CFR 51.24(b)(23)(iii)  and  40 CFR 52.21(b)(23)
(iii)] require that a proposed source or modification,  which plans  to
construct within 10 km of a Class I  area must demonstrate that if it  would
not impact the area, (less than 1 ug/m3) even if the proposed emissions are
below the applicable significant emissions rates listed in Table A-l.  If
the proposed source or modification  is within 10 km of  a Class I area,
proceed to box 6; if not, proceed to box 9.

Box 6.  Class I area screening procedure.

     If the proposed source or modification is within 10 km of a Class  I
area, then the screening procedures  described in reference 62 may be  used
to estimate the impact on the Class  I area.  This screening procedure is
based on a simple but conservative model for estimating each concentration
due to the emissions from the proposed source or modification.

Box 7.  More refined model (optional).

     A proposed source or modification may choose not to accept or  use  the
concentration estimates derived from the screening procedures in box  6, and
may elect to use a more refined model which would more  adequately reflect
the impact on the Class I area from  the proposed source or modification.
It should be emphasized that in order to perform a refined modeling analysis,
it may be necessary to collect 1 year of on-site meteorological data  for
the model input if an adequate amount of representative data are not  already
available.  The application of any model used in this analysis must be  con-
sistent with reference 14 as discussed in section 5.1.   The application of
any different model must be approved by EPA in order to avoid any delays in
the processing of the permit application.  Applicants should consult  with
the reviewing authority before investing considerable resources in  the  use  of
the different models.  Therefore, the documentation and specific description
of the model should be provided to the reviewing authority before the
results are submitted.

     The concentration estimates from the screening procedure or the  refined
model, are subsequently used in the  Part 4-Ambient Air Quality Analysis and
Part 5-Source Impact Analysis.

Box 8.  Will the proposed source or modification impact on a Class  I
        area?

      If a proposed source or modification is within 10 km of a Class  I
area, the proposed source or modification must be prepared to demonstrate
for each regulated pollutant it would emit that there would be no signifi-
cant  impact on the Class  I area.  Significant impact is defined in the PSD
regulations [40 CFR 51.24(b)(23)(iii) and 40 CFR b2.21(b)(23)(111)] as  1
microgram per cubic meter (ug/m3) or more, 24-hour average.
                                    A-16

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Box 9.  Are new emissions or net emissions increase of the regulated
        pollutant  >Table A-l?

     If the proposed source or  modification is  not  within  10  km of a  Class
I area, or if the proposed source is  within 10  km of a Class  I  area and  has
no significant impact on the Class I  area, then the emissions for each
pollutant from the proposed source of modification  are compared to the
significant emissions rates in  Table  A-l.

Box 10.  No further analysis for that pollutant.

     If the emissions from the  proposed source  or modification  are not
significant as defined in Table A-l,  no further analysis  is  required  for
that pollutant.  However, a similar review must be  performed  for all  other
regulated pollutants by proceeding to box  5 for the next  pollutant.

Box 11.  Is proposed construction a relocation  of a portable  facility
         with previous permit?

     This question is actually  an applicability question  that is normally
considered under the Part 1-Source Applicability Determination.  However,
there are certain other questions (see boxes 3, 5 and 8 of Figure A-2)
which are normally asked under  pollutant applicability that  are also  germane
to permitting a portable facility relocation.  Thus, the  reason for including
box 11 in Part 2.

     The source must be a portable facility which has previously received a
permit under the PSD regulations, the owner proposes to relocate the  facility,
and emissions at the new location would be temporary (not  exceeding its
allowable emissions).  If the facility meets these  requirements, then
proceed to box 12; if not, proceed to box  14.

Box 12.  Are there potential impacts  on a  Class I area, or areas of known
         increment violation?

     The emissions from the portable  source should  not exceed its allowable
emissions, and the emissions from the temporary source should impact  no
Class I area and no area where  an applicable increment is  known to be
violated.  If there are potentially adverse impacts on a  Class  I area, or
significant impacts on areas of known increment violation, proceed to box
14; if not, proceed to box 13.

Box 13.  No PSD permit required.

     If there are no potential  impacts on  a Class I area,  or  areas of known
increment violation, no PSD permit is required.

Box 14.  Apply BACT.

     "Best available control technology" means  an emissions  limitation
(including a visible emission standard) based on the maximum  degree of


                                    A-17

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reduction for each pollutant subject to regulation under the Act which
would be emitted from any proposed major stationary source or major
modification which the Administrator, on a case-by-case basis, taking into
account energy, environmental, and economic impacts and other costs,
determines is achievable for such source or modification through application
of production processes or available methods,  systems,  and techniques,
including fuel cleaning or treatment or innovative fuel combustion techniques
for control of such pollutant.  In no event shall  application of best
available control technology result in emissions of any pollutant which
would exceed the emissions allowed by any applicable standard under 40 CFR
Parts 60 and 61.  If the Administrator determines  that  technological  or
                     on the application of measurement  methodology to a
                     unit would make the imposition of  an emissions standard
                      equipment, work practice, operational  standard, or
                     may be prescribed instead to  satisfy the requirement
                    of best available control  technology. Such standard
economic limitations
particular emissions
infeasible, a design,
combination thereof,
for the application
shall, to the degree possible, set forth the emissions reduction achievable
by implementation of such design, equipment, work practice or operation,
and shall provide for compliance by means which achieve equivalent results.

Box 15.  Are the allowable emissions or the net emissions increase
         temporary, impacting no Class I area, or impacting no area
         where the PSD increment is violated?

     Temporary emissions are defined as emissions from a temporary source
that would be less than 2 years in duration, unless the Administrator
determines that a longer time period would be appropriate.  If all of the
conditions above are not met, proceed to box 16; if they are met, proceed
to Part 7-Complete PSD Application.

Box 16.  Will the proposed source or modification emit VOC?

     If the proposed source or modification will emit VOC, proceed to box
17; if not, proceed to box 20.  Also proceed to box 20 if the pollutants
are TSP, PMio, S02, CO, N02, or Pb.

Box 17.  Are VOC emissions < Table A-2?

     If the VOC emissions rates from the proposed source or modification
are less than the value in Table A-2 (100 tons/year), proceed to box 18;
if not, proceed to box 19.

Box 18.  Is there an apparent threat to the NAAQS, or is there a potential
         adverse impact on a Class I area?

     If the projected air quality after construction is equal to or greater
than 90 percent of the NAAQS, a threat to the NAAQS would generally exist.
Potential adverse impacts on a Class I area must be determined on a case-by-
case basis by the permit granting authority.  Therefore, if there is an
apparent threat to the NAAQS, or if there are potential adverse irrpacts on
a Class  I area, then proceed to box 19; if not, proceed to box 20.
                                    A-18

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Box 19.  Will  proposed source modification perform postapproval  monitoring
         in lieu of preconstruction monitoring data?

     The PSD regulations [40 CFR 51,24(m)(l)(v) and 40 CFR 52.21(m)(l)
(vi)] give special  considerations regarding  ozone monitoring data to new or
modified sources of volatile organic compounds which have satisfied all
conditions of  40 CFR 51, Appendix S, section IV.  This section generally
requires affected sources to meet lowest achievable emission rate limitations,
secure emissions offsets which provide an overall net air quality improvement,
and ensure all other major sources in the same State are in compliance  with
the applicable SIP.  If a proposed source or modification has met all  of
the above conditions for VOC, then the proposed source or modification  may
provide postapproval monitoring data for ozone in lieu of providing precon-
struction data.  Postapproval monitoring data are data collected after  the
date of approval of the PSD application.  However, in no case should the
postapproval monitoring be started later than 2 years after the start-up of
the new source or modification.

     If the proposed source or modification  will provide postapproval
monitoring, proceed to the Part 5-Source Impact Analysis; if not, proceed
to box 20 for the remainder of the ambient air quality analysis.

Box 20.  Estimate existing air quality.

     The proposed source or modification must perform an initial  analysis
to estimate the existing air quality concentrations.  The screening pro-
cedures described in reference 62 may be used.  The screening procedures
are based on simple models for estimating air quality due to the emissions
from existing and approved but not yet built sources.  A proposed source or
modification may choose not to accept or use the concentration estimates
derived from the screening procedure above,  and may elect to use a more
refined model  which would more adequately reflect the impact from existing
sources.  It should be emphasized that in order to perform a refined modeling
analysis, it is generally necessary to collect 1 year of on-site meteorological
data for the model  input.  The application of any model  used in this analysis
must be consistent with reference 14 as discussed in section 5.1.  The
application of any model should be approved  by the permit granting authority
to avoid any future delays in the processing of the permit application.
Therefore, the documentation of the specific description of the model
should be provided to the permit granting authority before the results  are
submitted.

     The concentration estimates from the screening procedure or the optional
refined model  will  be used in the remaining  portions of the ambient air
quality analysis.
                                    A-19

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Box 21.  Estimate air quality impacts of proposed construction.

     The proposed source or modification must estimate its air quality
impacts to demonstrate that its new pollutant emissions would not violate
either the applicable NAAQS or the applicable PSD increment.   The proposed
source or modification must use the screening procedures or more refined
model, consider "good engineering practice" for stack height, and consider
the TSP and S02 increment exclusion for Class II areas under 50 tons per
year exemption.  These factors are discussed in more detail below.

     (a)  Screening procedure or more refined model.

          If the proposed source or modification used the screening procedure
or more refined model in box 6 or 7 previously to estimate the impact, then
those results may be used in this impact analysis.  If the screening procedure
or more refined model was not previously determined, then the screening
procedures described in reference 62 may be used.  This screening procedure
is based on a simple model for estimating each concentration due to the
emissions from the proposed source or modification.  A proposed source or
modification may choose not to accept or use the concentration estimates
derived from the screening procedure above, and may elect to use a more
refined model which would more adequately reflect the impact from the
proposed source or modification.  It should be emphasized that in order to
perform a refined modeling analysis, it is generally necessary to collect 1
year of on-site meteorological data for the model input.  The application
of any model used in this analysis must be consistent with reference 14 as
discussed in Section 5.1.  The application of any model should be approved
by the permit granting authority to avoid any future delays in the processing
of the permit application.  Therefore, the documentation and specific
description of the model should be provided to the permit granting authority
before the results are submitted.

          The concentration estimates from the screening procedure or the
optional refined model will be used in the remaining portions of the ambient
air quality analysis.

     (b)  "Good engineering practice" (GEP) for stack height.

          The 1978 PSD regulations [1] provide for requiring GEP in the
impact analysis for stack heights.  The degree of emission limitations
required for the control of any air pollutant would not be affected by
stack heights (in existence after December 31, 1970) as exceeds good
engineering practice, or any other dispersion techniques implemented after
then.

     (c)  Consider 50 tons per year exemption.

          The PSD regulations [40 CFR 51.24(1)(7) and 40 CFR 52.21(i)(7)]
as they apply to a major modification exempt PMio and S02 from the Class II
increment consumption review if all of the following conditions are met:
                                    A-20

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(1) the net increase of all  pollutants  regulated  under the Act  after  appli-
cation of BACT would be less than  50 tons/year,  (2)  no pollutant  would  be
causing or contributing to a violation  of  the  standards (NAAQS),  and  (3)
source must have been in existence on March  1, 1978.  The  results of  the
impact analysis as  described in  this box will  be  used  for  subsequent  portions
of the ambient air  quality analysis.

Box 22.  Is the existing air quality <  Table A-2?

     The proposed source or modification must  determine the existing  air
quality concentration in the area  of impact  of the  proposed source or
modification before construction for each  applicable pollutant.   Modeling
by itself or in conjunction with monitoring  data  would be  used  for this
determination.  Application of these models  must  be  consistent  with
reference 14.

     If the proposed source or modification  is remote  and  not  affected  by
other readily identified man-made  sources, two options for determining
existing air quality concentrations from existing data are available.  The
first option is to  use air quality data collected in the vicinity of  the
proposed source or  modification, the second  option  is  to use average  measured
concentrations from a "regional" site to establish  a background concentration.
Additional guidance on determining the  background air  quality  concentrations
may be found in reference 14.  See also the  discussion or  use  of  representative
air quality data in Section 2.4 of this guideline.

     If the existing air quality is less than  the values in Table A-2,
proceed to box 24;  if not, proceed to box  23.

Box 23.  Are the air quality impacts <  Table A-2?

     The projected  impact of the proposed  source  or  modification  was
previously determined by the screening  procedure  or  refined model estimates.
These modeled concentrations are compared  to the  significant monitoring
concentrations shown in Table A-2.  If  these modeled concentrations are
less than the values in Table A-2, proceed to  box 24;  if not,  proceed to
box 25.

Box 24.  Is there an apparent threat to PSD  increments or  NAAQS,  or is
         there a potential adverse impact  on a Class I area?

     An apparent threat to a PSD increment is  consumption  by the  proposed
source or modification of 90 percent or more of the  remaining  allowable
increment.  An apparent threat to  the NAAQS  is when  the projected air
quality after construction is equal to  or  greater than 90  percent of  the
NAAQS.  Potential adverse impacts  on a  Class I area  must be determined  on  a
case-by-case basis  by the permit granting  authority.

     Therefore, if  there is an apparent threat to PSD  increments  or NAAQS,
or if there is a potential adverse impact  on a Class I area, proceed  to box
29; if not, proceed to box 28.


                                    A-21

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Box 25.  Are proposed emissions a criteria pollutant  or  VOC?

     Determine if the pollutant is a criteria  pollutant  (TSP,  PMiQ,  S02,  CO,
N02 or Pb) or VOC.  If the pollutant is  a  criteria  pollutant or  VOC,  proceed
to box 27; if not, proceed to box 26.

Box 26.  Is there an approved monitoring technique  available?

     Acceptable measurement methods currently  exist for  some noncriteria
pollutants, while other methods are currently  under review and have  not
been designated as an acceptable measurement method.   Section  2.6  of this
guideline discussed the designation of acceptable measurement  methods for
noncriteria pollutants.  If an acceptable  measurement method does  exist,
proceed to box 29; if not, proceed to box  28.

Box 27.  Preconstruction monitoring data required.

     Preconstruction air quality monitoring data are  required  for  this part
of the ambient air quality analysis.  The  proposed  source or modification
has the option of using representative air quality  data  or monitoring.
Considerations and constraints on the use  of existing data were  discussed
in Section 2.4 of this guideline.  It should be noted that a dispersion
model may be used in verifying the representativeness of the data.  If a
proposed source or modification chooses to monitor  instead of  using  repre-
sentative air quality data, then the specifics to be  followed  on network
design, probe siting, quality assurance, number of  monitors, etc., were
previously discussed in this guideline.

     The monitoring data required in this  box  will  be used in  Parts  5, 6
and 7 of the PSO permit application.

Box 28.  No preconstruction monitoring data required.

     If there is no approved monitoring technique for the noncriteria
pollutants, or if there is no apparent threat  to PSD  increments  or NAAQS,
or if there is no potentially adverse impact on a Class  I area,  then generally
no preconstruction monitoring data will  be required.   However, proceed to
the Part 5-Source Impact Analysis for remaining analyses.

Box 29.  Preconstruction monitoring data may be required.

     The permit granting authority must determine on  a case-by-case  basis
if monitoring data will be required when there is an  apparent  threat to  PSD
increments or NAAQS, or when there is a potential adverse impact en  a Class
I area.  Special attention must be given to Class I areas where  the  proposed
source or modification would pose a threat to  the remaining allowable
increment.  For those situations where the air quality concentration before
construction is near the concentrations shown  in Table A-2 and there are
uncertainties associated with this air quality determination then  precon-
                                    A-22

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struction air quality monitoring data may be required.   Some situations
where noncriteria monitoring may be required were discussed in Section
2.1.3 of this guideline.

     Regardless of the monitoring data decision,  proceed on to the Part
5-Source Impact Analysis for remaining analyses.
                                     A-23

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                               REFERENCES
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 3.   Federal  Register 44:51924-51959.  September 5, 1979.

 4.   United States Court of Appeals, No. 78-1006, Alabama Power Company,
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 7.   Federal  Register  44:27558-27604.  May 10, 1979.

 8.   Pace,  T.G.,  et^£l_. ,  Procedures for Estimating Probability of Non-
     attainment of  a PMio  NAAQS Using Total Suspended Parti cul ate or PMio Data.
     U.S.  Environmental Protection Agency, Research Triangle Park, NC.  EPA
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 9.   Ludwig,  F.L.,  J.H. Kealoha,  and E. Shelar.  Selecting Sites for
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10.   Ball,  R.J. and G.E.  Anderson.  Optimum Site Exposure Criteria for
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11.   Ludwig,  F.L. and  J.H.S.  Kealoha.  Selecting Sites for Carbon Monoxide
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12.   Ludwig,  F.L. and  E.  Shelar.  Site Selection for the Monitoring of
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                                    A-24

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13.  Pelton,  D.J.  and R.C.  Koch.   Optimum  Sampling  Site  Exposure  Criteria
     for Lead.   GEOMET Technologies,  Inc.,  Rockville,  MD.   Prepared  for
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14.  Guideline  on  Air Quality  Models  (Revised).   OAQPS,  U.S.  Environmental
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15.  Federal  Register  51:9582-9600.  March 19, 1986.

16.  Bryan, R.J.,  R.J. Gordon, and H. Menck.   Comparison of High  Volume  Air
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17.  Teer, E.H,  Atmospheric Lead Concentration Above  an Urban Street.
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18.  Bradway, R.M.,  F.A. Record,  and  W.E.  Belanger. Monitoring and  Modeling
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20.  Harrison,  P.R.  Considerations for  Siting  Air Quality  Monitors in Urban
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21.  Study of Suspended Particulate Measurements  at Varying Heights  Above
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22.  Rodes, C.E. and G.F. Evans.   Summary  of LACS Integrated  Pollutant
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23.  Lynn, D.A. et.  al.   National Assessment of the Urban  Particulate
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                                    A-25

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24.  Pace, T.6.  Impact of  Vehicle-Related  Particulates on TSP Concentrations
     and Rationale for Siting  Hi-Vols  in  the  Vicinity of Roadways.  OAQPS,
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25.  Air Quality  Criteria for  Lead. Office of  Research and Development,
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26.  Lyman, D.R.   The Atmospheric Diffusion of  Carbon Monoxide and Lead
     from an Expressway.  Ph.D.  Dissertation, University of Cincinnati, OH.
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27.  Burton, R.M. and J.C.  Suggs.   Distribution of Particulate Matter from
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28.  Koch, R.C. and H.E. Record. Network Design and Optimum Site Exposure
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29.  Wechter, S.6.  Preparation  of  Stable Pollutant Gas Standards Using
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30.  Wohlers, H.C., H. Newstein  and D. Daunis.   Carbon Monoxide and Sulfur
     Dioxide Adsorption On  and Description  From Glass, Plastic and Metal
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31.  Elfers, L.A.  Field Operating  Guide  for  Automated Air Monitoring
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32.  Hughes, E.E.  Development of Standard  Reference Material for Air
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33.  Altshuller,  A.D. and A.G. Wartburg.  The Interaction of Ozone with
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34.  CFR Title 40 Part 53.22,  July  1976.

35.  Butcher, S.S. and R.E. Ruff.   Effect of  Inlet Residence Time on Analysis
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36.  Slowik, A.A. and E.B.  Sansone. Diffusion  Losses of Sulfur Dioxide in
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37.  Yamada, V.M. and J.R.  Charlson.  Proper  Sizing of the Sampling  Inlet
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     Techno!., 3:483, 1969.


                                    A-26

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         38.   Quality Assurance Handbook for Air Pollution Measurement Systems;
              Volume I - Principles.  U.S. Environmental Protection Agency (MD-77)
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;'       39.   Quality Assurance Handbook for Air Pollution Measurement Systems;
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         40.   Traceability Protocol for Establishing True Concentrations of Gases
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         41.   Transfer Standards for Calibration of Ambient Air Monitoring Analyzers
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*-, •      42.   Cole, H.S.  Guidance for National Air Quality Trend Stations (NAQTS):
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         45.   Gill, G.C., L.E. Olsson, J. Sela, and M. Suda.  Accuracy of Wind
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                                            A-27

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49.  Holzworth, G.C.  Mixing Heights, Wind Speeds, and Potential  for Urban
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                                                                                    *»*
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52.  Workbook for Estimating Visibility Impairment.  U.S. Environmental
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53.  Guidelines for Siting and Exposure of Meteorological Instruments  for          ^  -
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     1976 (Draft).                                                                 4r*

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                                                                                     «•
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58.  Johnson, W.B. and R.E. Ruff.  Observational Systems and Techniques in
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     PA.  1973.                                                                      *.
                                    A-28
                     U.S. Environmental Projection Aqency
                     Region 5, L:';>.".ry (p[-i/;)

                                            12ih

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