ENVIRONMENTAL PROTECTION AGENCY
40 CFR Parts 51 and 52
[AH-FRL-5268-8; Docket No. A-92-65]
RIN 2060-AG04
[Federal Register: August 9, 1995 (Volume 60, Number 153)]
[Rules and Regulations]
[Page 40465-40474]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
ENVIRONMENTAL PROTECTION AGENCY
40 CFR Parts 51 and 52
[AH-FRL-5268-8; Docket No. A-92-65]
RIN 2060-AG04
Requirements for Preparation, Adoption, and Submittal of
Implementation Plans
AGENCY: Environmental Protection Agency (EPA).
ACTION: Final rule.
SUMMARY: The ``Guideline on Air Quality Models (Revised)''
(hereinafter, the ``Guideline''), as modified by supplement A (1987)
and supplement B (1993), sets forth air quality models and guidance for
estimating the air quality impacts of sources and for specifying
emission limits for them. The Guideline, codified as appendix W to 40
CFR part 51, is referenced in the PSD (Prevention of Significant
Deterioration) regulations and is applied to SIP revisions for existing
sources and to all new source reviews. On November 28, 1994 EPA issued
a Notice of Proposed Rulemaking to augment the final rule that was
published on July 20, 1993. Today EPA takes final action that makes
several additions and changes as supplement C to the Guideline.
Supplement C does the following: incorporates improved algorithms for
treatment of area sources and dry deposition in the Industrial Source
Complex (ISC) model, adopts a solar radiation/delta-T (SRDT) method for
estimating atmospheric stability categories, adopts a new screening
approach for assessing annual NO<INF>2 impacts, and adds SLAB and
HGSYSTEM as alternative models. This action is responsive to public
comments received. Adoption of these new and refined modeling
techniques and associated guidance should significantly improve the
technical basis for impact assessment of air pollution sources.
EFFECTIVE DATE: This rule is effective September 8, 1995.
ADDRESSES: Docket Statement: All documents relevant to this rule have
been placed in Docket No. A-92-65, located in the Air Docket (6102),
Room M-1500, Waterside Mall, Attention: Docket A-92-65, U.S.
Environmental Protection Agency, 401 M Street SW., Washington, DC
20460. This docket is available for public inspection and copying
between 8:00 a.m. and 5:30 p.m., Monday through Friday, at the address
above.
Document Availability: Copies of supplement C to the Guideline may
be obtained by downloading a text file from the SCRAM (Support Center
for Regulatory Air Models) electronic bulletin board system by dialing
in on (919) 541-5742. Supplement C may also be obtained upon written
request from the Air Quality Modeling Group, U.S. Environmental
Protection Agency (MD-14), Research Triangle Park, NC 27711. The
``Guideline on Air Quality Models (Revised)'' (1986), supplement A
(1987), supplement B (1993), and supplement C (1995) are for sale from
the U.S. Department of Commerce, Technical Information Service (NTIS),
5825 Port Royal Road, Springfield, VA 22161. These documents are also
available for inspection at each of the ten EPA Regional Offices and at
the EPA library at 401 M Street SW., Washington, DC.
FOR FURTHER INFORMATION CONTACT: Joseph A. Tikvart, Leader, Air Quality
Modeling Group, Office of Air Quality Planning and Standards, U.S.
Environmental Protection Agency, Research Triangle Park, NC 27711;
telephone (919) 541-5561 or C. Thomas Coulter, telephone (919) 541-
0832.
SUPPLEMENTARY INFORMATION:
Background <SUP>1
\1\ In reviewing this preamble, note the distinction between the
terms ``supplement'' and ``appendix''. Supplements A, B and C
contain the replacement pages to effect Guideline revisions;
appendix A to the Guideline is the repository for preferred models,
while appendix B is the repository for alternate models justified
for use on a case-by-case basis.
The purpose of the Guideline <SUP>2 is to promote consistency in
the use of modeling within the air management process. The Guideline
provides model users with a common basis for estimating pollution
concentrations, assessing control strategies and specifying emission
limits; these activities are regulated at 40 CFR 51.46, 51.63, 51.112,
51.117, 51.150, 51.160, 51.166, and 51.21. The Guideline was originally
published in April 1978. It was incorporated by reference in the
regulations for the Prevention of Significant Deterioration of Air
Quality
[[Page 40466]]
in June 1978 (43 FR 26380). The Guideline was subsequently revised in
1986 (51 FR 32176), and later updated with the addition of supplement A
in 1987 (53 FR 393). The last such revision was supplement B, issued on
July 20, 1993 (58 FR 38816). The revisions in supplement B included
techniques and guidance for situations where specific procedures had
not previously been available, and also improved several previously
adopted techniques.
\2\ Guideline on Air Quality Models ``(Revised)''(1986)[EPA-450/
2-78-027R], with supplement A (1987) and supplement B (1993),
hereinafter, the ``Guideline''. The Guideline is published as
appendix W of 40 CFR part 51. The text of appendix W will be
appropriately modified to effect the revisions incorporated as
supplement C.
During the public comment period for supplement B, EPA received
requests to consider several additional new modeling techniques and
suggestions for enhanced technical guidance. However, because there was
not sufficient time for the public to review the new techniques and
technical guidance before promulgation of supplement B, the new models
and enhanced technical guidance could not be included in the supplement
B rulemaking. Thus, in a subsequent regulatory proposal, EPA proposed
to revise the Guideline and sought public comment on the following four
items: incorporation of improved algorithms for treatment of area
sources and dry deposition in the Industrial Source Complex (ISC)
model, adoption of a solar radiation/delta-T (SRDT) method for
estimating atmospheric stability categories, adoption of a new
screening approach for assessing annual NO<INF>2 impacts, and addition
of SLAB and HGSYSTEM as alternative models.
Final Action
Today's action amends appendix W of 40 CFR part 51 to effect the
revisions known as supplement C, slightly modified in form since
proposal. All significant comments have been considered, and whenever
they revealed any new information or suggested any alternative
solutions, such were considered in EPA's final action.
As proposed, EPA is replacing the area source algorithm in the
Industrial Source Complex model with a new one based on a double
integration of the Gaussian plume kernel for area sources. This
replacement includes that of the finite line segment approximation
employed by the short term version of ISC and of the virtual point
source technique used in the long term version of ISC.
As proposed, EPA is replacing the dry deposition algorithm in ISC
with an improved technique that is more accurate for estimating
deposition for small (i.e., < 20<greek-m>m diameter) particles. Use the
deposition algorithm in modeling analyses in which particle settling is
considered important will remain optional.
EPA will adopt the solar radiation/delta-T (SRDT) method for
Pasquill-Gifford (P-G) stability classification discussed in section 9
of appendix W. However, instead of adopting the SRDT method as a
replacement for the currently accepted turbulence-based methods (i.e.,
<greek-s><greek-ph> and <greek-s><greek-th>), as proposed, SRDT will
join them as an ensemble of acceptable methods. Furthermore, while the
current hierarchy of acceptable methods is eliminated, the Turner
method using on-site wind speed and representative cloud cover
observations, remains the preferred classification method.
As proposed, EPA revises the annual NO<INF>2 screening technique
described in section 6 of appendix W. The new technique, known as the
Ambient Ratio Method (ARM), is simpler and less conservative than the
Ozone Limiting Method (OLM) it replaces.
As proposed, EPA adds two new models, namely SLAB and HGSYSTEM, as
alternative models for use on a case-by-case basis.
Discussion of Public Comments and Issues
All comments submitted to Docket No. A-92-65 are filed in Docket
Category IV-D. EPA has summarized these comments, developed detailed
responses, and drawn conclusions on appropriate actions for this Notice
of Final Rulemaking in an external Agency document.<SUP>3 In this
document, all significant comments have been considered and discussed.
Whenever the comments revealed any new information or suggested any
alternative solutions, such were considered in EPA's final action.
\3\ ``Summary of Public Comments and EPA Responses on the
Proposal for Supplement C to the Guideline of Air Quality Models
(Revised)''; August 1995 (Air Docket A-92-65, Item V-C-1).
Major issues raised by the commenters, along with EPA responses,
are summarized below. Guidance and editorial changes associated with
the resolution of these issues are adopted in the appropriate sections
of the Guideline and are promulgated as supplement C (1995) to the
``Guideline on Air Quality Models (Revised)'' (1986) (Docket Item V-B-
1). See the ADDRESSES section of this Notice (above) for general
availability.
Although a more detailed summary of the comments and EPA's
responses are contained in the aforementioned response-to-comments
document (Docket Item V-C-1), the remainder of this preamble section
overviews the primary issues encountered by the Agency during the
public comment period. This overview also serves to explain the changes
to the Guideline from today's action, and the main technical and policy
concerns addressed by the Agency. In our view, all of the changes being
made reasonably implement the mandates of the Clean Air Act, and are in
fact beneficial to both EPA and the regulated community. While modeling
by its nature involves approximation based on scientific methodology,
and entails utilization of advanced technology as it evolves, EPA
believes these changes respond to recent advances in the area so that
the Guideline continues to be comprised of the best and most proven of
the available models and analytical techniques, as well as reflect
reasonable policy choices.
Enhancements to the Industrial Source Complex (ISC2) Model
While for clarification these enhancements are discussed
separately, EPA will integrate these enhancements into one model for
actual use. Several conforming Guideline revisions will be made: (a)
the latest version of ISC that integrates the revised algorithms will
be called ISC3, and will hereafter be specified only in main references
(section 12) and in its description in appendix A; (b) the term
``ISC2'' (the version of ISC currently in use) in all but appendix A
(i.e., in sections 7.1, 7.2.2, 7.2.5, 7.2.8, 8.2.5 and 8.2.7) will be
revised to the more generic ``ISC'' to make future Guideline revisions
more manageable; and (c) section 4.2.1 will be amended to say that the
latest version of SCREEN (i.e., SCREEN3), a screening model that uses
ISC algorithms, will be specified in the main references, and
``SCREEN2'' in section 4.2.1 and 5.2.1.1 will be changed to ``SCREEN''.
A. Area Source Algorithm
There was general public support for adoption of the proposed area
source algorithm. Some concern, however, was expressed over the
evaluation of the algorithm's performance being based on wind tunnel
simulations. A commenter urged the Agency to evaluate the algorithm
using a particular ``available field data'' set. EPA had been aware of
the value of such data for evaluation purposes generally but the use of
the specific data set cited by the commenter was recommended against by
EPA's contractor. And since other such data sets were unavailable, EPA
feels that the wind tunnel evaluation was the best possible. EPA will
therefore adopt the algorithm, as proposed.
[[Page 40467]]
B. Dry Deposition Algorithm
No comments were received about the proposed algorithm's
performance in ISCST. Regarding ISCLT, however, concern was expressed
over the algorithm's 50-fold increase in deposition estimates for small
particles from near-surface releases compared with the current
algorithm. As explained in the response-to- comments document, EPA
investigated the commenter's perception and explained the apparent
disparity in performance is explicable in terms of a series of
independent effects related to the improvements made in the new
algorithm. EPA will adopt the algorithm, as proposed.
In the proposal, EPA solicited public comment on whether it would
be appropriate to require that the new dry deposition algorithm be used
for all ISC analyses involving particulate matter in any of the
programs for which Guideline usage is required under 40 CFR parts 51
and 52. No comments were received. EPA will continue to allow optional
use of the algorithm on a case-by-case basis, depending on the
application and on the availability of source specific, fractionated
emissions data.
2. Enhancements to On-Site Stability Classification
Much of the expressed public concern was based on a perception of
substantial added costs the SRDT method would add to meteorological
monitoring programs. As stated in the response-to-comments document,
investigation of the cost factors associated with instrumenting a
meteorological tower to implement the SRDT method (i.e., <greek-D>T and
insolation) showed that such would add approximately $2500-$3500.
Relative to the cost of all the monitoring equipment, including data
acquisition systems, tower, etc., the added instrumentation costs for
implementing the SRDT method are approximately 25 to 45 percent of the
total costs (depending on tower height). Thus, as was pointed out in
public comment, there is a capital cost associated with implementation
of the SRDT method, but EPA believes that cost is not excessive,
particularly in relation to the total monitoring program.
While no analyses were offered to directly refute the viability of
the SRDT method on a technical basis, there was general concern over
the SRDT method's proposed replacement of the currently acceptable
turbulence based methods (i.e., <greek-s><greek-ph> or
<greek-s><greek-th>), particularly given that the evaluation report for
the SRDT method did not demonstrate its superiority over the latter
methods.
Therefore, in an effort to balance an array of concerns, consistent
with the intent and motivation for the proposal, EPA will adopt the
SRDT method but revise the current hierarchical system of stability
classification in Guideline section 9.3.3.2. Specifically, the Turner
method using site-specific wind speed and representative cloud cover
and ceiling height will be preferred for estimating P-G stability
categories. This preference is founded in the fundamental radiation
basis for P-G categories. In the absence of requisite data to implement
the Turner method, however, the SRDT method or one of the turbulence
based methods may be used. Regarding the collection of requisite
representative cloud cover data for implementing the preferred Turner
method, it should be noted that the operative word is representative.
The previous distinction made for ``off-site'', associated with the
last choice in the current hierarchy, is semantic. ``On-site'' is a
preferable ideal; what is important is representativeness. As aptly
pointed out in public comments, when representative off-site'' cloud
cover data are judiciously used, there can be good P-G category
correspondence with what would have been obtained using strictly onsite
observations. The emphasis on representativeness, inherent in
EPA's final action, should obviate the historical contention over this
semantic issue. As stated in the proposal, the on-site guidance <SUP>4
will be revised by addendum to reflect the new stability classification
system, including the SRDT methodology. The document will also be
revised to add some additional guidance on considerations of
representativeness with respect to the Turner method.
\4\ Environmental Protection Agency, 1987. On-Site
Meteorological Program Guidance for Regulatory Modeling
Applications. EPA Publication No. EPA-450/4-87-013. U.S.
Environmental Protection Agency, Research Triangle Park, NC.
3. Screening Approaches for Assessing Annual NO<INF>2 Impact
Public comments were generally supportive of the proposed NO<INF>2
screening approach: the ARM. Some, however, recommended the retention
of OLM that ARM was proposed to replace. As stated in EPA's response,
this recommendation would imply that OLM, applied on an hourly basis as
a tertiary screening method, would yield a better estimation of annual
NO<INF>2 impact. EPA believes, however that application of OLM in this
manner is affected by several technical and logistical problems.
Because the oversimplified OLM approach does not necessarily result in
more accurate estimates, adding OLM as a third tier screening method to
be implemented on a hourly basis for screening is unnecessary.
Therefore, EPA will adopt the Ambient Ratio Method, as proposed.
4. Modeling Techniques for Toxic Air Pollutants
There was support for EPA's proposal to adopt two new models for
treating dense gas releases. Therefore, as proposed, EPA will add these
models, SLAB and HGSYSTEM Version 3.0, to the Guideline where they will
accompany DEGADIS, another appendix B model for treating dense gas
releases for use on a case-by-case basis.
Administrative Requirements
A. Executive Order 12866
Under Executive Order (E.O.) 12866 [58 FR 51735 (October 4, 1993)],
the Agency must determine whether the regulatory action is
``significant'' and therefore subject to review by the Office of
Management and Budget (OMB) and the requirements of the Executive
Order. The Order defines ``significant regulatory action'' as one that
is likely to result in a rule that may:
(1) Have an annual effect on the economy of $100 million or more
or adversely affect in a material way the economy, a sector of the
economy, productivity, competition, jobs, the environment, public
health or safety, or State, local, or tribal governments or
communities;
(2) Create a serious inconsistency or otherwise interfere with
an action taken or planned by another agency;
(3) Materially alter the budgetary impact of entitlements,
grants, user fees, or loan programs of the rights and obligations of
recipients thereof; or
(4) Raise novel legal or policy issues arising out of legal
mandates, the President's priorities, or the principles set forth in
the Order.
It has been determined that this rule is not a ``significant
regulatory action'' under the terms of E.O. 12866 and is therefore not
subject to OMB review.
B. Paperwork Reduction Act
This final rule does not contain any information collection
requirements subject to review by OMB under the Paperwork Reduction Act
on 1980, 44 U.S.C. 3501 et seq.
C. Regulatory Flexibility Act
The Regulatory Flexibility Act (5 U.S.C. 601 et seq.) requires EPA
to consider potential impacts of regulations on small ``entities''. The
final action taken today is a supplement to the notice of final
rulemaking that was published on July 20, 1993 (58 FR 38816). As
described earlier in this
[[Page 40468]]
preamble, the revisions here promulgated as supplement C to the
Guideline encompass the use of new model algorithms and techniques for
using those models. This rule merely updates existing technical
requirements for air quality modeling analyses mandated by various
Clean Air Act programs (e.g., prevention of significant deterioration,
new source review, SIP revisions) and imposes no new regulatory
burdens. As such, there will be no additional impact on small entities
regarding reporting, recordkeeping, compliance requirements, as stated
in the notice of final rulemaking (aforementioned). Furthermore, this
final rule does not duplicate, overlap, or conflict with other federal
rules. Thus, pursuant to the provisions of 5 U.S.C. 605(b), EPA hereby
certifies that the attached final rule will not have a significant
impact on a substantial number of such entities.
D. Unfunded Mandates
Under Section 202 of the Unfunded Mandates Reform Act of 1995
(``Unfunded Mandates Act''), signed into law on March 22, 1995, EPA
must prepare a budgetary impact statement to accompany any proposed or
final rule that includes a Federal mandate that may result in estimated
costs to State, local, or tribal governments in the aggregate; or to
the private sector, of $100 million or more. Under Section 205, EPA
must select the most cost-effective and least burdensome alternative
that achieves the objectives of the rule and is consistent with
statutory requirements. Section 203 requires EPA to establish a plan
for informing and advising any small governments that may be
significantly or uniquely impacted by the rule.
EPA has determined that the action promulgated today does not
include a Federal mandate that may result in estimated costs of $100
million or more to either State, local, or tribal governments in the
aggregate, or to the private sector. Therefore, the requirements of the
Unfunded Mandates Act do not apply to this action.
List of Subjects
40 CFR Part 51
Administrative practice and procedure, Air pollution control,
Intergovernmental relations, Reporting and recordkeeping requirements,
Ozone, Sulfur oxides, Nitrogen dioxide, Lead, Particulate matter,
Hydrocarbons, Carbon monoxide.
40 CFR Part 52
Air pollution control, Ozone, Sulfur oxides, Nitrogen dioxide,
Lead.
Authority: This rule is issued under the authority granted by
sections 110(a)(2), 165(e), 172 (a) & (c), 173, 301(a)(1) and 320 of
the 1990 Clean Air Act Amendments, 42 U.S.C. 7410(a)(2), 7475(e),
7502 (a) & (c), 7503, 7601(a)(1) and 7620, respectively.
Dated: July 25, 1995.
Carol M. Browner,
Administrator.
Parts 51 and 52, chapter I, title 40 of the Code of Federal
Regulations are amended as follows:
PART 51--REQUIREMENTS FOR PREPARATION, ADOPTION, AND SUBMITTAL OF
IMPLEMENTATION PLANS
The authority citation for part 51 continues to read as follows:
Authority: 42 U.S.C. 7410(a)(2), 7475(e), 7502 (a) and (b),
7503, 7601(a)(1) and 7620.
Sec. 51.112 [Amended]
2. In Sec. 51.112, paragraphs (a)(1) and (a)(2) are amended by
revising ``and supplement B (1993)'' to read ``, supplement B (1993)
and supplement C (1995)''.
Sec. 51.160 [Amended]
3. In Sec. 51.160, paragraphs (f)(1) and (f)(2) are amended by
revising ``and supplement B (1993)'' to read ``, supplement B (1993)
and supplement C (1995)''.
Sec. 51.166 [Amended]
4. In Sec. 51.166, paragraphs (l)(1) and (l)(2) are amended by
revising ``and supplement B (1993)'' to read ``, supplement B (1993)
and supplement C (1995)''.
5. Appendix W to part 51, section 4.2.1 is amended by removing
``SCREEN2, is available.<SUP>19, 20'' in the last sentence of the first
paragraph and adding ``SCREEN2, is available.<SUP>19, 20 For the
current version of SCREEN, see reference 20.''
6. Appendix W to part 51, section 4.2.2 is amended by revising
Table 4-1 to read as follows:
Appendix W to Part 51--Guideline on Air Quality Models
* * * *
Table 4-1.--Preferred Models for Selected Applications in Simple Terrain
Land use Model <SUP>1
Short Term (i.e., 1-24
hours):
Urban.................. RAM
Urban.................. RAM
Buoyant Industrial Rural.................. BLP
Line Sources.
Long Term (i.e.,
monthly, seasonal or
annual):
Urban.................. RAM
Urban.................. CDM 2.0 or RAM <SUP>4
Buoyant Industrial Rural.................. BLP
Line Sources.
Concentrations From Point Sources
Tier 1:
Assume Total Conversion of NO to NO<INF>2
Tier 2:
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