[Code of Federal Regulations]
[Title 40, Volume 18]
[Revised as of July 1, 2003]
From the U.S. Government Printing Office via GPO Access
[CITE: 40CFR93.123]

[Page 568-569]
 
                   TITLE 40--PROTECTION OF ENVIRONMENT
 
         CHAPTER I--ENVIRONMENTAL PROTECTION AGENCY (CONTINUED)
 
PART 93--DETERMINING CONFORMITY OF FEDERAL ACTIONS TO STATE OR FEDERAL 
IMPLEMENTATION PLANS--Table of Contents
 
   Subpart A--Conformity to State or Federal Implementation Plans of 
   Transportation Plans, Programs, and Projects Developed, Funded or 
       Approved Under Title 23 U.S.C. or the Federal Transit Laws
 
Sec. 93.123  Procedures for determining localized CO and PM10 
concentrations (hot-spot analysis).

    (a) CO hot-spot analysis. (1) The demonstrations required by 
Sec. 93.116 (``Localized CO and PM10 violations'') must be 
based on quantitative analysis using the applicable air quality models, 
data bases, and other requirements specified in 40 CFR part 51, Appendix 
W (Guideline on Air Quality Models). These procedures shall be used in 
the following cases, unless different procedures developed through the 
interagency consultation process required in Sec. 93.105 and approved by 
the EPA Regional Administrator are used:
    (i) For projects in or affecting locations, areas, or categories of 
sites which are identified in the applicable implementation plan as 
sites of violation or possible violation;
    (ii) For projects affecting intersections that are at Level-of-
Service D, E, or F, or those that will change to Level-of-Service D, E, 
or F because of increased traffic volumes related to the project;
    (iii) For any project affecting one or more of the top three 
intersections in the nonattainment or maintenance area with highest 
traffic volumes, as identified in the applicable implementation plan; 
and

[[Page 569]]

    (iv) For any project affecting one or more of the top three 
intersections in the nonattainment or maintenance area with the worst 
level of service, as identified in the applicable implementation plan.
    (2) In cases other than those described in paragraph (a)(1) of this 
section, the demonstrations required by Sec. 93.116 may be based on 
either:
    (i) Quantitative methods that represent reasonable and common 
professional practice; or
    (ii) A qualitative consideration of local factors, if this can 
provide a clear demonstration that the requirements of Sec. 93.116 are 
met.
    (b) PM10 hot-spot analysis. (1) The hot-spot 
demonstration required by Sec. 93.116 must be based on quantitative 
analysis methods for the following types of projects:
    (i) Projects which are located at sites at which violations have 
been verified by monitoring;
    (ii) Projects which are located at sites which have vehicle and 
roadway emission and dispersion characteristics that are essentially 
identical to those of sites with verified violations (including sites 
near one at which a violation has been monitored); and
    (iii) New or expanded bus and rail terminals and transfer points 
which increase the number of diesel vehicles congregating at a single 
location.
    (2) Where quantitative analysis methods are not required, the 
demonstration required by Sec. 93.116 may be based on a qualitative 
consideration of local factors.
    (3) The identification of the sites described in paragraph (b)(1) 
(i) and (ii) of this section, and other cases where quantitative methods 
are appropriate, shall be determined through the interagency 
consultation process required in Sec. 93.105. DOT may choose to make a 
categorical conformity determination on bus and rail terminals or 
transfer points based on appropriate modeling of various terminal sizes, 
configurations, and activity levels.
    (4) The requirements for quantitative analysis contained in this 
paragraph (b) will not take effect until EPA releases modeling guidance 
on this subject and announces in the Federal Register that these 
requirements are in effect.
    (c) General requirements. (1) Estimated pollutant concentrations 
must be based on the total emissions burden which may result from the 
implementation of the project, summed together with future background 
concentrations. The total concentration must be estimated and analyzed 
at appropriate receptor locations in the area substantially affected by 
the project.
    (2) Hot-spot analyses must include the entire project, and may be 
performed only after the major design features which will significantly 
impact concentrations have been identified. The future background 
concentration should be estimated by multiplying current background by 
the ratio of future to current traffic and the ratio of future to 
current emission factors.
    (3) Hot-spot analysis assumptions must be consistent with those in 
the regional emissions analysis for those inputs which are required for 
both analyses.
    (4) PM10 or CO mitigation or control measures shall be 
assumed in the hot-spot analysis only where there are written 
commitments from the project sponsor and/or operator to implement such 
measures, as required by Sec. 93.125(a).
    (5) CO and PM10 hot-spot analyses are not required to 
consider construction-related activities which cause temporary increases 
in emissions. Each site which is affected by construction-related 
activities shall be considered separately, using established 
``Guideline'' methods. Temporary increases are defined as those which 
occur only during the construction phase and last five years or less at 
any individual site.