L. Preston Bryant

, Jr. Secretary of Natural Resources 

# COMMONWEALTH a/VIRGINIA

DEPARTMENT OF ENVIRONMENTAL QUALITY

Street address : 629 East Main Street, Richmond, Virginia 23219

Mailing address : P.O. Box 1105, Richmond, Virginia 23218

Fax (804) 698-4500 TDD (804) 698-4021 www.deq.virginia.gov



## APR 0 4 Z0 08

Ms. Judith M. Katz

, Director

Air Protection Division (3APOO)

U.S. Environmental Protection Agency, Region III

1650 Arch S t reet Philadelphia

, Pennsylvania 19103-2029 David K. Paylor

Director

(804) 698-4000

1-800-592-5482

Reference: Plan to Improve Air Quality in

the Washington DC-MD- V A Region: SIP for the PM 2

. 5 NAAQS

Dear Ms. Ka t z:

Pursuant to the requirements of Section 110 of the Clean Air Act, we are officially requesting approval of a revision to the Commonwealth of Virginia State Implementation Plan (SIP) approv e d under the authority of § 10.1-1185 of the Code of Virginia and submitted in

accordance w ith the requirements of 40 CFR Part 51 (Requirements for Preparation, Adoption,

and Submitt a l of Implementation Plans). As provided in Section 174 of the Clean Air Act, the plan was pre p ared by the Metropolitan Washington Air Quality Committee (MWAQC). This
revision is e ffective March 7

, 2008.

This r evision consists of a demonstration of the progress being made to improve air quality in the Washington nonattainment area and the efforts underway to assure that all

necessary ste ps are taken to reac h the national ambient air quality standard for PM 2

. 5 by 2009

. The revision includes (i) the attainment plan, (ii) analysis of reasonably available control

measures, (ii i) attainment demonstration, (iv) contingency plans for failure to attain the air quality standard, (v) mobile source budgets, and (vi) the base year 2002 air pollutant emissions inventory.Enclosed are the following:

1. State Implementation Plan (SIP) for the Annual Fine Particulate (PM2.S) Standard

and the 2002 Base Year Inventory for the Washington, DC- MD- V A

N onattainment Area.

2. Certification of Public Participation Activities and Compliance with State

Administrative Procedures

3. Record of Hearing and Summary of Testimony

If you have any questions or need additional information, please let us know.

DKP\RAM\kgs

TEMPLATES\SIP-PLAN\PLNOO SIP\NONATTN PLANS\2008\NV Apm-SIP.DOC

EnclosuresENCLOSURE 2

CERTIFICATION OF PUBLIC PARTICIPATION ACTIVITIES AND COMPLIANCE WITH STATE ADMINISTRATIVE PROCEDURES

As required by 40 CFR 51.102(f) and Section 2.1(b) and (d) through (g) of Appendix V of 40 CFR Part 51, the following information regardi ng public participation activities and compliance with state administrative procedures is provided.

PUBLIC PARTICIPATION ACTIVITIES

As required by 40 CFR 51.102(a), a hearing to accept public testimony concerning a proposed revision to the Commonwealth of Virginia State Implementation Plan was
held at the George Mason High School, 7124 Leesburg Pike, Falls Church, Virginia , at 7:00 p.m. on January 28, 2008

.

In the National Capitol Interstate Air Quality Control Region, the public was given notice
of the hearing in the Washington T imes on December 28, 2007 (copy attached). As required by Section 2.1(g) of Appendix V of 40 CFR Part 51, the hearing was held in accordance with the information found in the public notice, and according to the state's
laws.

T he Regional Administrator for the U.S. Environmental Protection Agency was notified of the hearing, as was each local air pollution control agency which will be significantly
affected by the revision and is located in the affected Air Quality Control Regio n. In addition, the District of Columbia and Maryland, which share affected interstate Air Quality Control Regions with Virginia, were notified of the hearing. These notifications follow the requirements of 40 CFR Part 51.102(d).

The complete record of the hearings, along with any testimony received and responses thereto, is located at the Office of Air Regulatory Development of the Department of Environmental Quality. The d epartment contact to access this information is the Director, Office of Air Regu latory Development. A summary of the testimony received and responses thereto is attached.

COMPLIANCE WITH STATE ADMINISTRATIVE PROCEDURES

As required by § 2.2

- 4031 of the Code of Virginia, notice of the hearing was given to the public in the Virginia Register on January 21, 2008 (copy attached).

TEMPLATES \ SIP

- PLAN \ PLN02
SIP \ NONATTN PLANS \ 2008 \ NVApm

- SIP

- 2.DOCFRIDA Y. DECEUBER 18, 1007 *

AD81 01 77

_

### General Notices/Errata

Volume 24, Issue 10 DEPARTMENT OF ENVIRONMENTAL QUALITY

Air Quality Plan

Notice of action: 1be Department of Environmental Quality (DEQ) is announcing an opportWlity for public comment on a proposed plan to attain and maintain the national ambient air quality standard for PM 2 5 in the metropolitan Washington,

D.C. area, which includes the northern Virginia jurisdictions

of Loudoun County, Prince William County, Fairfax County, Arlington COWlty, the City of Falls Church, the City of Alexandria, the City of Manassas, the City of Fairfax, and the City of Manassas Park. If adopted, the Commonwealth

intends to submit the plan or portion thereof as a revision to
the Commonwealth of Virginia State Implementation Plan (SIP) in accordance with the requirements of §110(a) of the

federal Clean Air Act. The SIP is the plan developed by the

Commonwealth in order to fulfill its responsibilities W1der the

federal Clean Air Act to attain and maintain the ambient air quality standards promulgated by the U.S. Environmental

Protection Agency (EPA) tI1der the Act.

Purpose of notice: DEQ is seeking comments on the overall plan, including (i) the attainment plan, (ii) the analysis of reasonably available control measures, (iii) the attainment demonstration, (iv) the contingency plans for failure to attain

the air quality standard, (v) mobile source budgets, and (vi)

the baOle year 2002 air pollutant emissions inventory. 1be

base year 2002 air pollutant emissions inventory has been prepared in response to the emission inventory requirements

W1der §172(c) of the federal Clean Air Act in accordance with

40 CFR 51.915.

Public comment period: December 28, 2007, to January 30,

2008.

Public hearing: George Mason High School, 7124 LeesbtIg Pike, Falls Church, Virginia (within walking distance of the

West Falls Church Metro Station) at 7 p.m. on January 29,

2008.

Description of proposal: The proposed revision, "State Implementation Plan (SIP) for the Annual Fine Particulate (PM 25 ) Standard and the 2002 Base Year Inventory for the Washington, DC-MD-VA Nonattainment Area," was prepared by the :Metropolitan Washington Air Quality

Committee (MW AQC), which consists of elected officials

from the affected localities and repreOlentatives of state transportation and air quality planning agencies. The plan is

intended to show the progress being made to improve air quality in the Washington nonattainment area and the efforts W1derway to assure that all necessary steps are taken to reach

the federal health standard for PM 25 by 2009. MWAQC prepared the plan to comply with the Clean Air Act

Virginia Register of Regulations January 21, 2008

1318Amendments of 1990 and with federal implementation guidance.

Federal infonnation: This notice is being given to satisfy the public participation requirements of federal regulations (40

CPR 51.102). The proposal will be submitted as a revision to
the Commonwealth of Virginia SIP W1der §110(a) of the

federal Clean Air Act in accordance with 40 CPR 51.104. All provisions of the proposal are planned to be submitted as a revision to the Commonwealth of Virginia SIP.

How to comment: DEQ accepts written comments by email,

facsimile transmission, and postal mail. In order to be considered, written comments must include the full name, address, and telephone nwnber of the person commenting and

be received by DEQ by 5 p.m. on the last day of the comment period (January 30, 2008). Due to problems with the quality

of facsimile transmissions, commenters are encouraged to provide the signed original by postal mail within one week.

Both oral and written comments are accepted at the public hearing. DEQ prefers that comments be provided in writing, along with any supporting docwnents or exhibits. All testimony, exhibits, and docwnents received are part of the public record. Please note this proposed plan is being conclIrentiy reviewed by the U.S. EPA.

To review proposal: 1be proposal and any supporting

docwnents are available on the DEQ Air Public Notices for

Plans website: http://www.deq.virginia.gov/air/permittingfplanotes.html. The

docwnents may also be obtained by contacting the DEQ repreOlentative named below. 1be public may review the

docwnents between 8:30 a.m. and 4:30 p.m. of each business day W1til the close of the public comment period at the following locations: DEQ Main Street Office, 8th Floor, 629

E. Main Street, Richmond, Virginia, 804-698-4070; and DEQ

Northern Virginia Regional Office, 13901 Crown Court, Woodbridge, Virginia, 703-583-3800.

Agency Contact: Doris Mcleod, Air Quality Plannerillepartment of Air Data Analysis and Planning, 629

East Main Street, P.O. Box 1105, Richmond, VA 23218, telephone (804) 698-4197, FAX (804) 698-4510, or email damcleod@deq.virginia.gov.

Volume 24, Issue 10 Virginia Register of Regulations

1319 

### General Notices/Errata

January 21, 20081 ENCLOSURE 3

RECORD OF HEARING AND SUMMARY OF TESTIMONY

As required by 40 CFR 51.102(e), the complete record of the hearing, along with a list of witnesses and the text of the written presentations or summary of the oral presentations, is located at th e Office of Air Regulatory Development of the Department of Environmental Quality. The d epartment contact to access this information is the Director, Office of Air Regulatory Development.

As required by Section 2.1(h) of Appendix V of 40 CFR Part 51, bel ow is a summary of the testimony received and responses thereto. Included is a brief statement of the subject, the identification of the commenter, the summary of the comment and the response (analysis and action taken). Each issue is discussed in light of all of the
comments received that affect that issue. All comments have been reviewed and responses developed based on an evaluation of the issues raised in consideration of the overall goals and objectives of the air quality program and the intended pu rpose of
the document under review.

1. SUBJECT: Air quality analysis for PM 2.5 emissions

.

COMMENTER: Mirant Corporation

TEXT: The commenter objects to the inclusion of the requirement for Mirant Potomac River Generating Station (PRGS) to submit an air quality analysis for PM 2.5 emissions once methodologies for such an analysis are finalized. The requirement is found in Section 9.4.3 of the draft PM 2.5 SIP. No technical or legal basis exists for the inclusion of this requirement in the PM 2.5 SIP, a ctual monitoring data do not support the
conclusion tha t such an analysis is necessary, t he air quality analysis required to be submitted by PRGS has no relationship to the PM 2.5 attainment SIP, and PM 2.5 emissions from PRGS are well

- controlled.

RESPONSE : The technical and legal basis for the PRGS PM 2.5 ambient air quality analysis requirement is supported by law and regulation. 9 VAC 5

- 20

- 180 I gives the State Air Pollution Control Board authority to shut down a facility to prevent
violations of the NA AQS: “ Regardless of any other provision of this section, the owner of any facility subject to the Regulations for the Control and Abatement of Air Pollution shall, upon request of the board, reduce the level of operation at the facility if the board
deter mines that this is necessary to prevent a violation of any primary ambient air quality standard... ” 9 VAC 5

- 20

- 160 A provides the b oard authority to request information from registered facilities: “ The owner of any stationary source to which permits are iss ued under 9 VAC 5 Chapter 80 (9 VAC 5

- 80

- 10 et seq.) or for which emission standards are given in 9 VAC 5 Chapter 40 (9 VAC 5

- 40

- 10 et seq.), 9 VAC 5 Chapter 50 (9 VAC 5

- 50

- 10 et seq.), and 9 VAC 5 Chapter 60 (9 VAC 5

- 60

- 10 et seq.) shall, upon request of the board, register such source operations with the board and update such registration information. The information required for registration shall be2 determined by the board and shall be provided in the manner specified by the board .” 9 VAC 5

- 40

- 50 H req uires facilities to provide various reports at the request of the b oard:

“ Upon request of the board, the owner of an existing source subject to the provisions of this chapter shall provide notifications and report, revise reports, maintain records or

repo rt emission test or monitoring result in a manner and form and using procedures acceptable to the board... ” § 172(c)(1) of the federal Clean Air Act ( Nonattainment Plan
Provisions ) requires that plans shall “...provide for attainment of the national primary

am bient air quality standards.” § 172(c)(1) also requires that plans contain emission limitations and other such control measures, means, or techniques as may be necessary or appropriate to provide for attainment.

Although the actual monitoring data current ly available may not necessarily indicate the presence of a NAAQS violation for PM 2.5 attributable to PRGS, these data are
inconclusive to a certain extent. Violations of the NAAQS depend on numerous factors, including meteorology, facility stack configur ation, local area topography, emissions from other facilities, and regional load being transported into the area. Emission rates from any facility are dependent upon fuel type, demand, limitations placed on the facility by a variety of permits, and other operational and economic factors.

T here are also several uses of air quality data in evaluating the impacts from a facility such as PRGS. One of the most important, identified in the EPA’s Guideline on Air Quality Models, is the use of air quality measur ements “in a complementary manner to dispersion models, with due regard for the strengths and weaknesses of both analysis techniques.” While air quality measurements are particularly useful in assessing the accuracy of model estimates, such measurements d o not eliminate the need to apply a model to assess an individual facility’s impact. Although it is possible to use air quality measurements alone to assess NAAQS compliance, this approach would not likely be preferred unless available models are found to be unacceptable

, and monitoring data
ha ve sufficient spatial and temporal coverage.

Therefore, the presence of local monitoring data showing no NAAQS violation does not obviate the need for a specific facility analysis using a model.

The PM 2.5 air quali ty analysis does indeed have a relationship to the PM 2.5 attainment plan. The facility operates within the boundaries of the nonattainment area and is considered to be upwind of many other nonattainment areas such as Baltimore and Cecil County in Maryland

.

T he federal reference monitoring program for PM 2.5 in the metropolitan Washington area is one of the most robust monitoring networks in the U nited S tates. Based on the data from this federal reference monitoring program, the nonattainment area has
demo nstrated compliance with the annual PM 2.5 standard of 15.0 μ g/m 3 . However, attainment plans often focus on specific facilities as well as the overall regional air quality. For instance

, facility

- specific RACT requirements may be enumerated within
attainm ent plans, and facility

- specific requirements may also be used for contingency measures in attainment plans as well as maintenance plans. An important part of the3 attainment plan is the assumptions made for growth in various emissions categories
and how s uch growth is incorporated into the attainment plan. To take into account growth in emissions, the state may examine specific facilities or types of facilities to determine likely growth rates. Therefore, specifying requirements or specifying facility
da ta for a particular facility is not a deviation from past or current attainment planning practices. Ascertaining whether or not a facility

— particularly one that has engendered enforcement actions and significant public comment

-- does not cause or contribut e to a
PM 2.5 ambient air quality violation in an area that currently does not contain a federal reference monitor, via an approved analysis methodology, is clearly an appropriate topic for the PM 2.5 attainment plan.

Whether or not the description of “well

- controlled” should be applied to the e xisting
PM 2.5 control devices at PRGS (electrostatic precipitators) is unclear. A comparison of
tested emission ra tes, as provided by the commente r in a different submittal, to those required by the existing source r egulations in 9 VAC 5

- 40 ( Existing Stationary Sources ) indicates that PRGS appears to operate at well below 0.12 lb PM /mmbtu. However, a comparison of those same emission rates , and emission limitations in the draft PRGS permit, to limitations placed on n ew coal

- fired boilers through the Best Available Control Technology (BACT) process show s that the limitations on new coal

- fired boilers may be somewhat more stringent.

Regardless of whether or not the facility is “well

- controlled,” other factors often aff ect ambient air quality impacts, including facility and local topographical configurations, as
discussed above. Therefore, the existence of PM 2.5 control devices does not make the requirement for an ambient air quality analysis moot.

2. SUBJECT: PM 2.5 i mpacts from the PRGS power plant.

COMMENTER: City of Alexandria

TEXT: The attainment plan does not contain a detailed description of how existing permit programs will be specifically impl emented, or enhanced, in regard to
PM 2.5 . The attainment plan should contain more rigorous monitoring, permitting, and enforcement programs

RESPONSE: For the purposes of determining attainment of a NAAQS by a regional area, federal reference monitoring (FRM) data must be used to show compliance or noncompliance wi th the standard. The existing FRM network in the metropolitan Washington area consists of 14 PM 2.5 monitors and is one of the most robust monitoring networks in the country. For years 2003

- 2005 as well as for years
2004

- 2006, this monitoring network has demonstrated compliance with the 1997 PM 2.5 standards of 15.0 μ g/m 3 on an annual basis and 65 μ g/m 3 on a 24

- hour basis. FRM data for the year 2007 are not currently available for Maryland and Washington, D.C. However, DEQ has completed quality assurance reviews and has certified the Virginia
2007 PM 2.5 data. These data show that the highest measurements in northern Virginia
reflect PM 2.5 design values of 14.1 μ g/m 3 on an annual basis and 34.0 μ g/m 3 on a 24

-4 hour basis, well beneath both 1997 standards.

T his draft attainment p lan is designed to address the 1997 standards. In 2006, new standards were promulgated that lowered the 24

- hour requirement to 35 μ g/m 3 PM 2.5

. The attainment demonstration process for the new standard will be undertaken at a
later da te. The attainment planning process for the 1997 standard must occur prior to and independently from the process needed for the 2006 standards. The main purpose of this attainment plan therefore continues to be demonstrating compliance with the
1997 stan dards.

Section 8.2 of the draft attainment plan discusses the changes made to the major stationary source permitting program in regard to PM 2.5 . Section 8.4 notes the intention by the state agencies to adopt further PM 2.5 nonattainment permitting require ments, including requirements for precursor emissions, controls

, and offsets, when these

reg ulations are finalized by EPA.

In the 2008

- 2010 Grant Work Plan, of which both EPA Region III and DEQ are part ies

, DEQ has a grant commitment to submit a draft NSR SIP for PM 2.5 nonattainment areas no later than 6 months after EPA finalizes the PM 2.5 NSR implementation rule. This commitment is found under Objective 1.1

- Healthier Outdoor Air, Sub Objective 1.1.1

– More People Breathing Cleaner Air, Work Plan Compone nt

– NAAQS NSR.

It is therefore clear that Virginia intends to adopt the EPA’s finalized version of nonattainment permitting requirements when they become available

. T o include in the draft attainment plan an outline of these requirements prior to publica tion of a final
version would be premature

, since EPA has published little regarding these new regulations

, and since changes are always likely betwee n proposed and final versions.

Additionally, including in an attainment plan specific requirements of the new source review permitting program would be duplicative. The new source review permitting program is published under a separate chapter of the Regulations for the Control and
Abatement of Air Pollution and is thus subject to the Administrative Process Act, including that statute’s public participation requirements . Modeling requirements that may be necessary for the program are generally guidelines published by EPA and used by many states across the country. If such detail s were included in the attainm ent plan, any changes made to modeling guidance or the new source review program would also necessitate a revision of the attainment plan, which is a time

- consuming, resource

intensive process. Therefore, it is not appropriate or necessary to include addi tional detail about the permitting progr am within the attainment plan.

3

. SUBJECT: Implementation of existing permit programs.

COMMENTER: City of Alexandria

TEXT: The existing permitting program and regional/national control programs
alone are insu fficient to accomplish the SIP goal. The goals must be accomplished as5 expeditiously as possible, mindful of 2006 standards. Rigorous monitoring programs and more severe limitations are necessary due to model uncertainty. Lax permitting, monitoring, and compliance programs allow increases of emissions over this attainment plan’s emissions inventories and caps.

RESPONSE: The programs outlined within the attainment plan are in fact sufficient to accomplish the SIP’s goals. FRM data show that the region has already attained the 1997 standards of 15.0 μ g/m 3 on an annual average and 65 μ g/m 3 on a daily average. These accomplishments are attribut able to many of the control programs implemented in previous attainment plans for ozone. Additional federal,

st ate, and supplemental control programs, as outlined in the draft attainment plan, will continue to reduce precursor and direct emissions of PM 2.5 . This attainment plan will
continue to improve air quality.

It is indeed important to be mindful of the 2006 PM 2.5 NAAQS standard on a regional basis. For years 2004

- 2006, only one regional FRM located in Washington, D.C.
showed a 24

- hour design value above 35 μ g/m 3 . The data for all states ha ve not yet been certified for years 2005

- 2007. However, Virginia ’s data ha ve been certified for these years, and th e s e data show all monitors in northern Virginia have 24

- hour averages of no more than 34.0 μ g/m 3 . On a regional basis, th ese data show that air quality is improving and appears to be attaining or nearly atta ining the 2006 standard.

Modeling uncertainty does exist and is documented as part o f the modeling evaluation report. However, EPA has recognized the fact that PM 2.5 models have intrinsic uncertainties due to many factors, including but not limited to th e complex nature of
PM 2.5 formation and the current state of the science of PM 2.5 modeling. To address these uncertainties, EPA requires the use of the modeling results in a relative sense
rather than an absolute sense. V irginia must make comparisons bet ween modeling outputs for 2002 and 2009

, then use these ratios with actual FRM data to predict future design value s. Direct model output results for 2009 may not be used to show future attainment status. The use of the modeling outputs in a relative sens e, coupled with the current improved air quality in the metropolitan Washington D.C. area, does not support the development of more stringent permitting requirements than those that will be published for implementation of the PM 2.5 nonattainm ent permitting program.

It is important to note differences between regional modeling protocols and facility

specific point source modeling that is performed for new and modified units under the Prevention of Significant Deterioration (PSD) m ajor n ew s ource r eview perm itting

p rogram. Modeling performed within the PSD permitting program to determine if a facility causes or contributes to a NAAQS violation is performed when guidance for such analyses is available. Additionally, such analyses are typically performed at t he facility’s potential to emit or permitted levels to ensure that all levels of operation by the

new facility will not have an impact on the NAAQS.

Regional modeling inventories are based on actual emissions and projected emissions. A facility’s projecte d emissions are rarely as high as its potential to emit. Projected6 emissions are generally extrapolated using a base year’s actual emissions inventory and applying a conservative growth factor, as required by EPA. In some instances, projected emissions a re adjusted based on control estimates . However, projected emissions are almost never based on potential to emit of a facility. Using such a methodology region

- wide would drastically inflate the point source emissions inventory
of an area. Such inflatio n of the projected emissions inventory could result in the implementation of costly and unnecessary regional control measure s . Such mitigation efforts cannot be supported if there is every reasonable expectation that PM 2.5 air quality is good and getting better, as indicated by the FRM data. Therefore, it is not appropriate to set projection year emission inventories equal to permitted limits or potential to emit.

Virginia’s permitting, enforcement, and monitoring programs are far from lax. Facilities

t hat trigger major new source review permitting in the northern Virginia PM 2.5 nonattainment area, either as new or modified sources, must install technology deemed to meet lowest achievable emission rates (LAER). This technology determination does
not all ow the cost of a control device to be considered in feasibility studies, making it a very stringent hurdle. Additionally, offsets must be obtained to ensure that emissions increases will not adversely affect regional air quality. These permitting require ments are quite stringent and will continue to be applied in PM 2.5 nonattainment area s

.

The Commonwealth clearly enjoys a strong, capable enforcement and monitoring

program at both the regional and state level. The air compliance and enforcement staff

at DEQ’s Northern Regional Office conducted 209 full compliance evaluations of facilities, reviewed 55 stack tests, and conducted 96 Stage II inspections i n 2007. A total of 83 enforcement follow

- ups were conducted in 2007 as well. Additionally, in 2007, t he northern Virginia Inspection and Maintenance Program performed 463 overt inspections and 177 covert inspections. These inspections resulted in 138 inspectors and/or stations being fined, lo sing licenses, or otherwise being prohibited from operating. A cross the Commonwealth, DEQ conducted over 8,500 full compliance
evaluations , more than 200 stack tests reviews, and over 390 enforcement follow

- ups.

4

. SUBJECT: RACT/RACM

COMMENTER: City of Alexandria.

TEXT: The attainment plan does not discuss ad ditional RACT/RACM in enough
detail.

RESPONSE: 40 CFR 51.1010, which delineates requirements for reasonably available control measures (RACM) and reasonably available control technology (RACT), predicates the implementation of a suite of measures on whe ther those measures can collectively advance the attainment date of a nonattainment area by one

year . Since the metropolitan Washington area is currently attaining the 1997 PM 2.5 NAAQS, based on FRM data for 2003

- 2005 and 2004

- 2006, it is not possible for any suite of measures to advance attainment. This explanation is provided in section 8.3 of7 the draft attainment plan. No further requirements or discussions of RACT/RACM are necessary for the plan to be approved. Therefore, the RACT/RACM requirements for this attainment plan are satisfied.

5

. SUBJECT: Monitoring and opacity standards.

COMMENTER: City of Alexandria.

TEXT: U.S. EPA’s Clean Air Fine Particulate Implementation Rule s uggests the use of more stringent monitoring and opacity standards

. Virginia’s current opacity standard of 20% allows PM 2.5 emission increases without adequate review. Opacity limitations should be strengthened to no more than 10%.

RESPONSE: How the current opacity standard for large boilers allows
emissions increas es above a baseline is unclear. However, the justification for examining monitoring and opacity standards as discussed in EPA’s Clean Air Fine Particulate Implementation Rule (72 FR 20586, April 25, 2007) is that of RACT/RACM.
The commenter is referencing language found in 72 FR 20617 which is in the context of observations on control opportunities when examining requirements for RACT/RACM.
As noted in the response to comment 4 , RACT/RACM requirements are predicated on advancing the attainment date, which is not possible for the metropolitan Washington area. Therefore, unless a facility undergoes a major modification as part of the new source review major permitting process ( in which case LAER must be applied ) , or undergoes a minor modification ( in which case BACT must be applied ) , there currently is no basis for reviewing source

- specific opacity standards appl ied to major stationary

sources.

6

. SUBJECT: CMAQ analysis.

COMMENTER: City of Alexandria

TEXT: CMAQ generally over

- predicts during winter m onths and under

- predicts during summer months. This aspect of model performance cannot be considered acceptable. Statistical metrics such as fractional error and bias do not provide assurance that the model predictions meet the modeling performance goals on either a
24

- hour or an annual basis. There is no observed error in model performance on the end model result in the target year of 2010. The design value calculations should include columns of maximum predicted values that reflect the model’s worst

- c ase performance for this modeling domain. The analysis relies too heavily on the trend in
observed PM 2.5 levels.

RESPONSE: A critical component of every air quality modeling study is the model performance evaluation (MPE) in which the modeled estimates for the current year base case are compared against observed values to assess the model’s accuracy and provide an indication of its reliability.8 The first step in the modeling process is to verify the model’s performance in terms of its ability to predic t PM 2.5 and its individual components (i.e., sulfate, nitrate, ammonium, organic carbon, elemental carbon and other PM 2.5 ) in the right locations and at the right levels. To do this, the model predictions for the base year simulation are compared to the am bient data observed in the historical episode.

The MPE included in the metropolitan Washington attainment plan was developed based on input from several regional planning groups such as the Mid

Atlantic/Northeast Visibility Union, the Ozone Transport Comm ission

, and the Association for Southeastern Integrated Planning. Specifically, all elements of the modeling platform, including the emissions, meteorology

, and air quality model

, have undergone an evaluation. The MPE consists of a combination of statist ical and graphical evaluations recommended by EPA in its guidance. After review of the MPE, if the model appears to be producing PM 2.5 in the right locations for the right reasons, then the model can be used as a predictive tool to evaluate various contr ol strategies
and their effects on PM 2.5

.

The issue of model performance goals for PM 2.5 is an area of ongoing research and
debate. Performance goals refer to targets that a well

- performing model should achieve, whereas performance benchmarks are based o n historical model performance measures for the best performing simulations. Performance goals are necessary in order to provide consistency in model applications and expectations across the country and to provide standardization in how much weight may be accorded modeling study results in the decisionmaking process. The model performance goals and criteria are

n ot regarded as a pass/fail test but rather as a basis of inter

- comparing model performance across studies, sensitivity tests

, and models.

The re sults of the MPE for the metropolitan Washington area for PM 2.5 and its individual species indicate that the CMAQ model performance for surface PM 2.5 is good

, with acceptable bias and error. The MPE was consistent with EPA guidance and includes the proper statistical performance metrics.

EPA and DEQ recognize that although good model performance remains a prerequisite for use of a model in an attainment demonstration, problems posed by less than ideal model performance on individual days are reduced throu gh the use of the model results in a relative sense. Furthermore, starting with an observed concentration as the base value reduces problems in interpreting model results. It is recognized that model results and projections will continue to have associat ed uncertainty. The attainment demonstration that EPA recommends recognizes this by including modeling plus other supplemental analyses such as air quality trends to determine whether all available evidence supports a conclusion that a proposed emission re duction plan will suffice to meet the NAAQS.

In summary, the issues identified by the commenter are not regulatory requirements and are not appropriate for inclusion in the attainment demonstration

, since attainment tests are based on the application of r elative response factors. The regional and local9 model performance is acceptable for PM 2.5 and was evaluated using EPA

- approved procedures. While there are some differences between the spatial data between sub

regions, there is nothing to suggest a tende ncy for the model to respond in a systematically different manner between regions. Examination of the statistical metrics by sub

- region confirms the absence of significant performance problems arising in one area but not in another, building confidence th at the CMAQ modeling system is operating consistently across the full modeling domain. This confidence in the modeling results allows for the modeling system to be used to support the PM 2.5 attainment plan.

7

. SUBJECT: Unmonitored areas

.

COMMENTER: C ity of Alexandria

TEXT: The proposed SIP provides no assurance that attainment with the NAAQS will be achieved in unmonitored areas where local

- scale modeling is the only means for determining compliance. Alexandria is an unmonitored area. Detailed

sp ecial purpose monitoring data show time periods when concentrations at Marina Towers approached or exceeded the NAAQS. These data present a clear indication that the regional monitors are not representative of concentrations in Alexandria and
that an unmo nitored area analysis must be conducted.

RESPONSE: T he information presented by the commenter compare s all monitoring data to the 2006 daily 35 μ g/m 3 standard. This attainment plan is directed at the 1997 standards, for which the daily standard is 65 μ g/m 3 . Data provided do not
exceed 65 μ g/m 3

.

Additionally, use of exceedence periods is not particularly helpful in comparisons to the NAAQS. Each NAAQS standard contains both a numerical limitation and a statistical methodology for computing that standa rd from monitoring data. The statistical methodology, for example an annual average or a fourth highest, three

- year average, is partly due to concerns of exposure time and rates. To violate a NAAQS, the standard must be surpassed using the appropriate st atistical approach. The Clean Air Act concerns itself with violations of the NAAQS, not exceedences. Exceedences must therefore be considered data variability, not actionable violations

.

In regard to the inclusion of an unmonitored area analysis, t he re gional modeling attainment demonstration does not address future air quality at locations where there is

n o PM 2.5 monitor nearby. To guard against the possibility that air quality levels could exceed the standard in areas with limited monitoring, EPA sugg ests that additional review is necessary, particularly in nonattainment areas where the PM 2.5 monitoring network just meets or minimally exceeds the size of the network required to report data

to the Air Quality System. This review is intended to ensure t hat a SIP control strategy
leads to reductions in PM 2.5 and its constituent pollutants at other locations that could have baseline (and future) design values exceeding the NAAQS were a monitor deployed there. The test is called an u nmonitored a rea a nalysi s (UAA).10 The UAA uses a combination of the 12

- km gridded model output and ambient data. The analysis should include, at a minimum, all nonattainment counties and counties surrounding the nonattainment area. Based on DEQ ’s initial review of the gridded

m odel output and ambient data, the UAA is unlikely to reveal any areas where future design values would exceed the NAAQS in the metropolitan Washington area.

EPA stresses that due to the lack of measured data, the examination of concentrations as part of t he UAA is more uncertain than the monitor

- based attainment test. EPA’s guidance recommends that predicted violations of the unmonitored area analysis be carefully scrutinized to determine whether they are likely to exist in the ambient air or whether they may be caused by an error or uncertainty in the modeling system. At a minimum, it may be appropriate to commit to additional deployment of ambient monitors in areas where the UAA predicts future violations. This monitoring would allow a better

assessment in the future of whether the NAAQS is being met at currently unmonitored
locations. In fact, in many ways the analysis of PRGS using special purpose monitors has already fulfilled the goal of the UAA. T he PRGS should not be considered an
“unmonitored are a” based on the fact that there is a continuous PM 2.5 monitor operating on the southeast property line and an FRM located on the roof of Marina Towers. The Marina Towers FRM monitor site is located in the area of expected maximum impact from PRGS. PRGS r emains one of the best monitored sources in Virginia.

Predicted violations of the UAA should be handled on a case

- by

- case basis. As such, additional analyses and tracking requirements may be needed depending on the nature of the problem and the uncertaint y associated with the potential violations. EPA also
stated at its June 2007 PM 2.5 modeling workshop that the UAA was not designed to
look for unmonitored PM micro

- scale hot

- spot issues. This would preclude the use of the UAA as a useful technique in eva luating impacts from an individual source such as PRGS.

DEQ is currently in the process of conducting the UAA for the metropolitan Washington

area

. DEQ is also part of the test group for the recently released beta version of EPA’s
Model Attainment Test Software (MATS), which is the tool requi red to conduct the UAA. Unfortunately, this tool is limited and does not have the spatial field feature necessary to complete the UAA. EPA expects that this component will be added in the next version of MATS and DE Q will complete the analysis upon release of the updated
software.

The metropolitan Washington area currently has a network of 14 PM 2.5 monitors. Several of these monitors were established as State and Local Air Monitoring Stations (SLAMS). These SLAMS monitors were selected based on specific monitoring objectives (background concentration, area of highest concentration, high population, source impact, transport, and rural impact) as required by EPA and siting scales (micro, middle, neighborhood, urban, and regional) established by EPA. It is believed that the density of the monitoring network relieves the necessity of applying the UAA. Despite being confident that the monitoring network is robust for the metropolitan Washington11 area , once the final ver sion of the MATS tool has been released, and after sufficient peer review and proper guidance for the analysis of the results is provided, DEQ will complete the UAA.

8

. SUBJECT: Modeling analysis.

COMMENTER: City of Alexandria

TEXT: No FRM monitor exists in Alexandria. Additionally, monitoring alone, especially within the impact area of a large source, is insufficient to demonstrate NAAQS compliance. Only through a modeling analysis that includes a robust receptor network can NAAQS protection be a ssured. DEQ should immediately address primary impacts of PM 2.5 in the local areas surrounding PRGS. Modeling tools are available.

RESPONSE: DEQ is examining the possibility of installing either a special

purpose PM 2.5 monitor or a PM 2.5 FRM within Al exandria. Whether or not such a monitor can be sited and operated within Alexandria depends on a number of issues, including personnel and monetary resources as well as locating an appropriate site for
such a monitor. If at all possible, DEQ would prefer to gather necessary monitoring data to determine air quality wit hin Alexandria’s city limits. DEQ is also exploring the possibility of PRGS continuing to operate at least one of the two PM 2.5 monitoring stations they currently are using to gather air qua lity data.

The statement that NAAQS protection can be assured only through a modeling analysis
is inaccurate. As stated elsewhere , t here are several uses of air quality data in evaluating the impacts from a facility such as PRGS

. One o f the most importa nt uses identified in the EPA’s Guideline on Air Qu a lity Models is the use of air quality
measurements “in a complementary manner to dispersion m o dels with due regard for the strength and weaknesses of both analysis techniques.” W h ile air qua lity

measurem ents are particularly useful in assessing t h e accurac y of model estimates,
these measurements do not necessarily eliminate the need to apply a model to assess an individual facility’s impact. Although it is possible to use air quality measurements
alone t o assess NAAQS compliance, this approach would not likely be preferred unless
available models are found to be unacceptable

, and monitoring data has sufficient

s patial and temporal coverage.

Additionally, f or certain pollutants, such as SO 2 , conservative EPA

- approved modeling analyses are indeed available and can be used for such a purpose. However, this is not the case for all pollutants. For example, there is no source

- specific, EPA

- approved modeling approach for ozone from facilities that emit VOC and NO X ; nor do appropriate modeling methodologies exist for estimating direct PM 2.5 impacts. A few states have published guidance for estimating impacts from new or modified sources using state

specific significant impact levels. No federal guidance has ye t been finalized on such protocols. Currently, it is unclear what type of anal yses EPA will require in regard to

source

- specific PM 2.5 emissions. Modeling may not be a part of such analytical guidance. Adoption of other states’ guidance, which was inten ded for use on new and12 modified facilities and not existing facilities, would set a precedent for use in other areas of the Commonwealth. Due to its highly conservative nature, u se of such guidance may unjustifiably prohibit the construction or modificati on of facilities within the Commonwealth. Use of such guidance, as applied to existing facilities, may unjustifiably require source curtailment or othe r expensive operational changes

.

Section 9.4.3 requires an analysis be performed after an analytical ap proach is finalized by EPA and peer reviewed. This analysis may or may not involve Gaussian modeling of some type. Regardless, the analysis will be performed to ensure PM 2.5 NAAQS compliance by PRGS.

9

. SUBJECT: Modeling analysis.

COMMENTER: City of Alexandria

TEXT: In Section 9.4.3, DEQ defers any modeling analysis of the PRGS facility until an appropriate implementation methodology for PM 2.5 is established, which appears to be an acknowledgement that the proposed SIP is deficient and that a more appropriate implementation plan is necessary.

RESPONSE: Section 9.4.3 was in no way added to address any “deficiency

. ” It was included to address Alexandria’s concerns regarding PM 2.5 air quality even though the special purpose monitors in the c ity do not show violations of either the 1996 or the
2006 PM 2.5 NAAQS standard. I ncluding such requirements to address concerns is an appropriate use of the attainment plan. However, it is not a requirement of the PM 2.5 planning process to address any particul ar facility, and the plan would be complete and approvable without this language. Generally, such facility concerns should be
addressed within the normal state permitting processes. In this case, the language in Section 9.4.3, much of which is also inclu ded in the recent draft permit for PRGS, was added to the draft attainment plan in part to help build a consensus with Alexandria’s participants in the planning process and to help provide assurances to the citizens that air quality it being protected.

10

. SUBJECT: Local area analysis.

COMMENTER: City of Alexandria.

TEXT: Alexandria strongly recommends that a local area analysis (LAA) be
conducted.

RESPONSE: The LAA uses dispersion models to address observed primary
PM 2.5 contributions at monito rs. Specifically, in areas with large spatial gradients of primary PM 2.5 , dispersion models are best suited to characterizing the change in primary PM 2.5 in the future. Areas that are relying on local primary particulate matter
controls to reach attainmen t should submit a LAA as part of the primary attainment demonstration. In other areas, a LAA may be useful as a supplemental analysis.13 EPA also states in its guidance that the dispersion modeling results should be evaluated to ensure adequate model perfor mance. Similar to photochemical grid modeling, the dispersion model results should be compared to ambient data to ensure that the model is working well. Many of the same statistical calculations used for photochemical grid modeling are recommended for eva luating primary PM 2.5 and PM 2.5 components predicted by a dispersion model.

The LAA is used to determine the actual (or typical) contrib ution from sources at a monitor, and the model results are used in a relative sense. Therefore, it is only appropriate (and in fact conservative) to use actual emissions in the base year and projection year emissions inventories . Using actual emissions should lead to a reasonable estimate of air quality improvements from reducing emissions at the contributing sources. Usin g allowable emissions might lead to an overestimate of
benefits from emissions controls.

The LAA appears to be an optional element of the SIP modeling demonstration, and the need for this analysis is considered on a case

- by

- case basis. The LAA is likely not required by EPA as part of the metropolitan Washington attainment planning process. This is due to the fact that the monitoring network does not have any observed spatial gradients of primary PM 2.5 and that the attainment plan does not need to rely on local primary PM 2.5 controls to reach attainment.

Based on its review of existing monitoring data, EPA initially did not invite DEQ to participate in a LAA workshop that was conducted in October 2007. However, due to concerns expressed by stakeholders, DEQ requested and was granted approval by EPA to attend this workshop. The focus of the workshop centered on areas that have elevated primary PM 2.5 concentrations in their core urban areas or that contribute to their highest FRM. At this time, no monitor s within the metropolitan Washington area are projected to exceed the NAAQS so it does not appear to be a necessary requirement in this circumstance to conduct the LAA. All of the regional monitors are projected to reach attainment with the PM 2.5 NAAQS in 2009. T he future year inventory projections have significant decreases in primary PM 2.5 and PM 2.5 precursors resulting from various control programs throughout the region. Furthermore, existing monitoring data suggest a uniform regional pattern with res pect to PM 2.5 concentrations . No monitor’s data appears significantly different, on average, than data gathered at other
monitors within the FRM network. For these reasons, no LAA is necessary.

11

. SUBJECT: Proposed permit for PRGS.

COMMENTER: C ity of Alexandria

TEXT: DEQ ’s proposed permit for PRGS is contradictory to SIP goals. The inventory used in the attainment plan regional modeling exercise is less than proposed permit limits and therefore underestimates emissions.14 RESPONSE: T he proposed permit is not contradictory to SIP goals. The goal of the attainment plan is to demonstrate compliance by 2009 with the 1997 PM 2.5 NAAQS standards. Current FRM data show, as discussed in other responses, that the region is indeed meeting the 1997 PM 2.5 NAAQS standards. The proposed PRGS permit reduces emissions from the baseline year for this facility. T he proposed permit will improve air quality and is not contrary to the goals of the PM 2.5 attainment plan.

As noted elsewhere , there are differences b etween regional modeling protocols and facility

- specific point source modeling that is performed for new and modified units under the PSD Major NSR p ermitting p rogram. Modeling performed within the PSD permitting program to determine if a facility causes o r contributes to a NAAQS violation is performed when guidance for such analyses is available. Additionally, such analyses are typically performed at the facility’s potential to emit or permitted levels to ensure that all levels of operation by the facilit y will not have a negative impact on the NAAQS.

Regional modeling inventories are based on actual emissions and projected emissions, partly due to the fact that the model is regional in nature. Projected emissions are rarely, if ever, as high as the pote ntial to emit of a facility. To assume that projected emissions equal potential to emit for every facility in the point source inventory over an entire region would drastically inflate emission estimates in the projection year, especially considering the conservative nature of the other projection estimates. For instance, the emission factors for area source categories are generally highly
conservative. These estimates are further inflated

, since many grow in relation to population increases, which in th e northern Virginia area are quite high. Additionally, transpor t ation budgets in the projection year do not take into account transportation

e mission reduction measures, which account for many tons of emission reductions and
are withheld for use in rare c onformity situations. Transportation emissions also do not take into account emission reductions achieved through DEQ ’s on

- r oad e missions

t esting program, which monitors the tailpipe emissions of vehicles to locate and repair polluting automobiles between required station inspections. Therefore, the 2009 projection year inventory is very conservative. As noted in the response to comment 8

, inflation of the projected point source emissions inventory may result in the implementation of costly and unnecessa ry regional control measure s . Such mitigation efforts cannot be supported if there is every reasonable expectation that PM 2.5 air quality is good and getting better, as indicated by the FRM data. Therefore, projection year emission inventories will not b e set to be equal to permitted limits or potential to
emit.

1 2. SUBJECT: PRGS reduced operational loads.

COMMENTER: City of Alexandria

TEXT: The SIP does not address the reduced operational loads of PRGS that were important events in relation to th e downward 24

- hour design level trends between
2002

- 04 and 2003

- 05. Chapter 9 should include a thorough discussion, along with a timeline that matches the implementation of the regional programs with the FRM15 monitoring results and include the effects of v arious actions concerning PRGS on the decline in regional values.

RESPONSE: Detailed discussion s of every facility’s operational changes
between 2002 and 2009 are not necessary. The goal of the attainment plan is to demonstrate compliance with the 1997 PM 2.5 NAAQS by 2009 on a regional basis. The attainment plan discusses the enforceable limits of the Virginia CAIR c aps, to which PRGS is subject, as well as a variety of other control measures and their expected overarching effect on air quality, such a s the Maryland Healthy Air Act and a coal

- to

natural gas conversion made at a nearby power plant. None of these descriptions include greatly detailed accounts of each measure or strategy since the sum total of all
the reductions are used to show that PM 2. 5 regional air quality in northern Virginia and metropolitan Washington is good and getting better. Additionally, providing in Chapter 9 a discussion of various control strategy and programs implementation schedules as they correspond to FRM monitoring re sults would be an incredibly lengthy process, given the number and variety of control programs that have gone into or are scheduled to go into effect between 2002 and 2009. Such an analysis would have to include reductions from such significant source sec tors as the power industry, the transportation sector , the petroleum fuel sector , auto body refinishing, surface coating, and many others. Such an analysis is unnecessary in any event due to the regional
context of the att ainment plan.

13

. SUBJECT: PM 10 as a surrogate for PM 2.5

.

COMMENTER: City of Alexandria

TEXT: DEQ should not rely on PM 10 as a surrogate for PM 2.5 in the permitting process for PRGS. EPA has suggested, in May 31, 2006, correspondence from Mr. Donald Welsh to Congressman James Mor an that the PM 2.5 SIP is an appropriate place to address the issue of PRGS’ air quality issues.

RESPONSE: T he PM 2.5 attainment plan is not an appropriate arena in which to discuss federal permitting guidance, adopted by DEQ , in regard to the use of PM 10 as a surrogate for PM 2.5 . Such permitting concerns are more appropriately addressed through the many significant public participation opportunities afforded the public during the permitting process. In any event, the current permitting guidance is ap pro priate
since it reflects recommended federal guidance on the issue of PM 2.5 in permits.

Regarding the EPA documentation sent to Congressman Moran, the draft PRGS permit satisfies the suggestions made in this letter regarding enforcement of the PM 2.5 NAAQS . Page 3 of the addendum provided by Mr. Welsh notes that “Even following approval of the SIP for PM 2.5 , it may be that the only enforceable restrictions on Mirant are a general, statewide provision limiting PM 2.5 emissions, or a specific PM 2.5 permit
lim it given to the PRGS through the normal Virginia permitting process. A permit limit
for PM 2.5 is the most likely mechanism; however, at present Mirant is not subject to any such permit limits.”16 PRGS air quality issues are being addressed through the norm al permitting process.
Re quirement s of the permit and of the draft attainment plan as listed in Section 9.4.3
mandate an ambient air quality analysis after methodologies for such analyses are
finalized. U se of the normal permitting process is appropriate for addressing specific facility concerns.

14

. SUBJECT: Ambient air quality analysis.

COMMENTER: City of Alexandria

TEXT: Language in Section 9.4.3 requiring an ambient air quality analysis is deficient since it fails to insure that the analysis w ill be done in a timely manner. It also suggests that methodology to conduct such an analysis is not available at the present time, which is contrary to existing EPA guidance. The language should be revised to
read: “U sing an available Gaussian dispersi on model, such as AEROMOD, for stationary sources, which has been approved by USEPA to model primary PM 2.5 impacts, DEQ shall conduct an ambient air quality analysis of the emissions of PM 2.5 from the Mirant Potomac River Power Generating facility. DEQ sh all complete this analysis within 120 days of adoption of the SIP by MWAQC. ”

RESPONSE: T he language suggested by the commenter is not appropriate. As
noted elsewhere , it is not certain that Gaussian dispersion modeling will be a requirement of PM 2.5 am bient air quality analyses. EPA has not yet published modeling guidance for PM 2.5 pollution. Use of published guidance for other pollutants, such as SO 2 , is not prudent given that the highly complex nature of PM 2.5 chemistry may not make the use of guida nce for other pollutants applicable. If Gaussian dispersion modeling is eventually required, no federal guidance currently exists explaining the application to PM 2.5 of this technique, which is multi

- faceted and highly complicated.

DEQ is committed to wo rking with the public, regulated community, and other stakeholders in the development of appropriate PM 2.5 guidance. DEQ has formed a
PM 2.5 Implementation Workgroup, which was announced on the Virginia Regulatory
Town Hall on January 2, 2008. This announ cement solicited participation in a workgroup responsible for the development of a draft policy to evaluate both new and existing sources that have the potential to emit of PM 2.5 in quantities that could have possible significant adverse health and environ mental impacts. This approach goes beyond that of other s tates that have developed procedures that evaluate new and modified facilities only. DEQ seek s membership from environmental and health organizations, academia, the legal profession, and industry o r trade associations that have a background in air quality modeling, policies, or programs to serve on this workgroup. The first meeting will likely take place in March 2008. Due to the exploratory nature of the work group, no estimation of a time frame f or pro ject completion can be made. However, DEQ will be providing the board periodic updates on the progress of workgroup efforts.17 The language included in Section 9.4.3 states that the timeline for submitting the analysis will be determined by DEQ . Thi s language was included to account for the fact that the requirements of the ambient air quality methodology are not known so that a reasonable timeframe cannot currently be fixed. However, it is reasonable for DEQ to require that PRGS submit a protocol o nce the final methodologies are approved by the
board within a certain time frame. DEQ will also commit to publishing this document on
the DEQ website so that citizens may review the contents. Section 9.4.3 has been updated to reflect this change and now reads as follows :

Based on a schedule and protocol to be established by DEQ after US EPA promulgates final rules
for PM 2.5 analysis, or UE EPA promulgates revised implementation guidance or policy for PM 2.5 analysis, or DEQ establishes a more appropriate implementation methodology for PM 2.5 , Mirant Potomac River Power Station shall conduct an ambient air quality analysis for the emissions of
PM 2.5 from the facility. No later than 60 days after approval of the implementation methodology by the Virginia St ate Air Pollution Control Board, Mirant Potomac River Power Station shall provide to DEQ a detailed protocol outlining how the facility will implement the approved methodologies. DEQ will make this document available to the public by publishing this proto col on the DEQ
website.

Even without these changes , the language in Section 9.4.3 clearly indicates DEQ’s intention to require an analys i s, once methodologies are determined, within a reasonable period of time.

15

. SUBJECT: V oluntary measures

.

COMMENT ER: City of Alexandria

TEXT: Alexandria request s the inclusion of various measures that the city funds
and oversee s in the attainment plan, as these measures are directionally correct and improve air quality.

RESPONSE: T he supplemental measures as l isted by the commenter have
been added to the plan.

16

. SUBJECT: PRGS impact s on PM 2.5 concentrations in the City of Alexandria

.

COMMENTER: Fairfax County Federation of Citizen's Associations

TEXT: The commenter requests that the Community Multi

- sc ale Air Quality ( CMAQ ) model be re

- run to calculate a design value for a model node point representative of downtown Alexandria.

RESPONSE: The CMAQ modeling results cannot be run as requested by the
commenter and still conform to EPA guidance on how CMA Q results should be used.
As noted in elsewhere , EPA recommends the use of CMAQ results in a relative sense when calculating future design values. In other words, CMAQ is run for both 2002 and 2009, and estimated concentrations for PM 2.5 for each year ar e used to create a ratio.18 This ratio may be thought of as 2009 divided by 2002 ; however, this explanation is somewhat oversimplified since PM 2.5 is a composite of a variety of different chemical compounds that must be factored into the equation. The calc ulated ratio of 2009 to 2002 is then applied to actual 2002 monitored design values at FRMs to calculate the projected 2009 design values for each monitoring site. EPA recommends the use of CMAQ in this manner for many reasons. One reason such methodolog y is
recommended is the state of the science of PM 2.5 modeling, which is really in its infancy. EPA recognizes that the model does not account for many physical and chemical properties of PM 2.5 and therefore believes using the model in a r elative sense

pr ovides more certain results. Another reason such methodology is recommended is the belief that actual monitoring data should play a significant role in the projected design value calculations. Using the CMAQ results in the relative sense ensures that
the design value projections have a strong basis in actual monitoring results.

Since no FRM monitor exists in Alexandria, this modeling exercise cannot be performed according to EPA guidance. N ote that in the response to comment 8 , consideration is being gi ven to locating a special purpose PM 2.5 monitor or a PM 2.5 FRM in the c ity.

17

. SUBJECT: PRGS impact s on PM 2.5 concentrations in the City of Alexandria

.

COMMENTER: Fairfax County Federation of Citizen's Associations

TEXT: The attainment plan should include a Gaussian dispersion model for PRGS of direct fine particulate emission s with downwash. D ata from the model should not be added to background concentrations to address the issue that background
concentrations may include the effects of PRGS’s em issions.

RESPONSE: S pecific facility concerns, including results of any air quality analysis performed on PRGS or any other facility, do not belong in a regional attainment plan. Due to significant facility concerns, Section 9.4.3, which reiterates the requirement in the draft permit for PRGS, requires an ambient air quality analysis be performed on PRGS’s emissions when methodology for such an analysis is finalized. Including the results of the Gaussian dispersion model performed by the City of
Alexan dria on this facility as part of the attainment plan would not make the plan any more approvable. T he draft attainment plan is fully approvable in its current state. Including the results of the Gaussian dispersion model may also be premature since it
is unclear what methodology will be recommended for PM 2.5 ambient air quality analyses. If the recommended methodology is something other than a Gaussian dispersion model, including the results of such modeling in the attainment plan could be misleading. L astly, it is unclear what purpose including the results of Alexandria’s Gaussian dispersion model with the background concentration removed would serve.
The following table below shows Alexandria’s calculated impacts by PRGS in the Gaussian model :19 PRG S Modeled PM 2.5 Impacts (Case ID

- 5 units operating at mid

- range load for 24 hours per day)

24

- hour (μg/m 3 ) Annual (μg/m 3 ) Stack Impacts on Elevated Receptors:

3

- year avg. of 8 th

- highest, stacks alone, among all Marina Towers rooftop receptors. 6.5 0.9

Coal and Ash Yard Impacts on Ground

- level Receptors:

3

- year avg. of 8 th

- highest, ground

- level, from coal and ash yard sources only. 8.2 2.6

Background

3

- year avg. of 8 th

- highest, closest monitor. 34.1 14.1

**NAAQS 35**  **15 .0** 

Not including the background c oncentrations would demonstrate a maximum impact of
8.2 μ g/m 3 on a 24

- hour basis, far less than either the 1997 24

- hour standard of 65

μ g/m 3 or the 2006 24

- hour standard of 35 μ g/m 3

. The maximum impact of 2.6 μ g/m 3 on an annual basis is far less than 15.0 μ g/m 3

. I ncluding this information does not provide any additional insight to the regional air quality issues of the metropolitan Washington

area.

18

. SUBJECT: C larifying text, technical details, and growth rates for area source
emissions inventories.

COMMENTER: Fairfax County Federation of Citizen's Associations

TEXT: (a) Figure 2

- 5 does not include data for March through September of 2005. (b) Text in Section 2.2.4 does not appear to support the figure. Perhaps different plots should be used. (c) Figure 2

- 10 needs more explanation, especially concerning the reasons for not considering ammonia emissions for control purposes in the SIP. Also, terms on the figure need more explanation. (d) Figure 2

- 11 is misleading. The axis should be changed to re flect zero or should contain a jog to indicate that the axis doesn’t begin at zero. (e) The plan needs to clarify the difference between area “non stationary” sources and mobile sources. A definition for “county

- equivalent” should be provided. Non

- road a irport vehicles need to be mentioned in Section 3.2.2. (f) The commenter suggests examining certain sectors of the area source emissions inventory to determine if appropriate growth factors have been used. The specific sectors
mentioned are residential fu el combustion, open burning, municipal landfills and incineration, and fugitive dust emissions.

RESPONSE: (a) This figure has been updated to include information through
December 2005. (b) An updated figure and additional information within the text of the
section have been added. (c) Figure 2

- 10 has been updated to better explain the content and terms of the figure. However, the reasons why ammonia is not considered a significant precursor to PM 2.5 are explained thorough ly in the plan, including Sectio n 2.8. (d) The range of the y axis in Figure 2

- 11 was defined from 14.0 to 17.5 in order to clearly demonstrate a declining design value trend line. Extending the y axis to zero instead of 14.0 creates a trend line that is nearly flat. A flat trend line does not clearly20 indicate the significant level of air quality improvement measured by the FRM network

. Also, data are labeled for design values for different years

, and the annual PM 2.5 standard line is clearly delineated in the graph. T he figure is qui te clear in its meaning. (e) A sentence has been added to Section 3.2.3 to define what constitutes a mobile source. Section 3.2.2 provides details about area sources, and the discussions in
these two sections make clear distinctions between area and mobil e sources. E xamples have been added to illustrate the differences between area “non stationary” and mobile sources. Since the MWAQC area inventory is calculated at county level, the term “county

- equivalent” is not relevant and has been deleted. Non

- road airport
vehicles are included in the non

- road inventory

. (f) DEQ has examined the open burning emissions category and found updated guidance for determining emissions from this source sector. However, for the other mentioned sectors, growth surrogates
fo r different area and nonroad source categories were decided in consultation with the
state air a gencies’ staff and the Emissions Inventory Sub

- Committee of the Technical Advisory Committee. These factors are the most appropriate factors available to
inven tory staff and have therefore been employed in inventory development. As EPA provides additional guidance on how these emissions inventories should be developed, such guidance will be examined for use in future inventories.

19

. SUBJECT: Health effects o f PM 2.5

.

COMMENTER: Ms. Crenshaw

- Van Fleet, citizen and member of the Air Quality Public Advisory Committee (AQPAC)

TEXT: The attainment plan makes no mention that the reductions, contingencies, or controls as docum ented will cause a reduction in t h e occurrences of
the hea l th c o ndition s and problems c a u sed by PM 2.5

. Will health problems and conditions associated by the Department of Energy with PRGS in its SEA decrease with the application of this attainment plan? Results from a study done by the Ag ency for Toxic Su b stan ces a n d Dise a s e Registry are due sometime in late winter or early spring of 2008. This study should be carefully reviewed.

R ESPONSE : Language has been adde d to the attainment plan to indicate that
attainment of the PM 2.5 NAAQS, as well as further air quality improvements, will have a positive influence on the health and well

- being of the citizens of the Commonwealth.

The attainment plan requires that PRGS perform an ambient air quality analysis when the methodology for such an ana lysis is finalized. The results of this study may show that additional controls on PRGS are needed to ensure the PM 2.5 NAAQS is met. The purpose of the attainment demonstration is to ensure that the region meets the NAAQS in a timely manner . The plan al so ensures that further air quality improvements will be enjoyed by the citizens of the metropolitan Washington area . However, the federal Clean Air Act does not mandate that a study demonstrating health benefits from each control program as applied withi n each separate nonattainment area be provided to create an approvable plan. While such information would certainly be interesting and noteworthy, DEQ does not have the resources to undertake such an endeavor. Such21 an endeavor is also not a necessary req uirement of the PM 2.5 attainment planning

process.

The study from the Agency for Toxic Substances and Disease Registry will be reviewed by DEQ

.

20

. SUBJECT: PM 2.5 monitors located near large PM 2.5 sources

COMMENTER: Ms. Crenshaw

- Van Fleet, citizen and member of AQPAC

TEXT: Current PM 2.5 monitors at PRGS do not meet siting criteria and thus cannot be used for this SIP. Are there other point sources in the Metropolitan Washington Region that would benefit from properly sited PM 2.5 monitors? Any and all
locations that are considered sources of PM 2.5 emissions should have PM 2.5 monitors properly sited under E P A criteria.

R ESPONSE : One monitor located near PRGS ( on top of Marina Towers ) uses federal reference measurement methods to collect data on th at site. The location does
not meet the criteria for FRM monitoring site s
, since FRM siting criteria include
limitation s on the height of the sampling probe. T he criteria suggest that appropriate heights for probes should be approximately equal to the le vel at whi ch an average person breathes.

However, data from this site ha ve not been discounted. Since the FRM testing methodology requires the use of a laboratory to anal yze filters, FRM s are not real time monitors. In other words, there is a lag betwee n the sample collection time and when the results of the laboratory analyses are received. For the FRM on the top of Marina Towers, at the time the draft SIP was being written, DEQ ha d 10 months of 2007 data, January through October. To calculate an annu al average, 12 months of data are needed. As a place holder, data from November and December of 2006 were used to examine the annual average at that monitoring site. The data indicate an annual average for one year of 13.7 μ g/m 3 , well below 15.0 μ g/m 3

. This information was not included in the draft attainment plan because using November 2006 through October 2007 data is an irregular method of calculating an annual average; because three years of data were not available from this monitoring site, as requi red by the statistical methodology for the NAAQS ; and because the calculated annual average was well
beneath the 15.0 μ g/m 3 standard. In early February of 2008, the final months of PM 2.5 data for 2007 at the Marina Tower monitors became available. For Ja nuary through December 2007, the Marina Towers monitor measured an annual average of 13.5

μ g/m 3 and a 24

- hour average of 31.3 μ g/m 3

. DEQ will continue to examine the data gat hered from this monitoring site.

As discussed elsewhere

, DEQ is considering loca ting a PM 2.5 monitor within the City of
Alexandria due to concerns raised about PRGS

. To summarize, PM 2.5 FRMs are
resource intensive ( installing a PM 2.5 FRM costs approximately $13,000 each with an annual operations cost of approximately $15,000 ), and DE Q must operate within its22 resource constraints. Adding additional monitors to the already robust monitoring
network in the area would be quite costly without show ing any great deviation from the measurements made at the current FRM sites. To date, the FR Ms in the metropolitan Washington area do not appear to show a great deal of data deviation, indicating that
the PM 2.5 air quality in the metropolitan Washington area is more a regional issue than
it is a localized issue. I t is not necessary or cost effec tive to locate FRM s near every major point source of PM 2.5 emissions in the metropolitan Washington area.

21

. SUBJECT: Emissions from PRGS

.

COMMENTER: Ms. Julie Crenshaw

- Van Fleet, citizen and member of AQPAC

TEXT: Mirant Potomac River Generating S tation is a point source considered to be a high polluter by EPA. High polluters should be considered hot spot problem
locations. The use of TRONA at PRGS, and its effects on PM 2.5 emissions and human
health , should be discussed in the attainment plan.

RESPONSE: EPA does not define a “ hot spot ” within regional modeling guidance. The current EPA guidance for regional modeling to support attainment plans
notes that LAA s are required for areas within a region that show elevated monitored
PM 2.5 concentrat ions at monitors within the federal reference monitoring network when compared to data from other federal reference monitors in the region. There is no identified gradient in PM 2.5 concentrations in the FRM network in the metropolitan Washington region. Therefore, b y EPA’s definition, there is no requirement to conduct a local area analysis. DEQ is aware of highly conservative micro

- scale modeling that indicates the possibility of a hot spot in the City of Alexandria even though current data
from the mon itors located in the modeled area show that concentrations are well beneath the NAAQS. Additionally, FRM monitoring data at the nearby monitoring station in Arlington show compliance with the NAAQS. Regardless, the attainment plan does include requiremen ts for further actions to address the concerns regarding emissions from PRGS through additional analyses, when methodologies become available, as required by Section 9.4.3.

Regarding the use of TRONA injection for SO 2 control at the PRGS , t he attainment p lan
is not an appropriate place to enumerate details about a specific facility’s operational considerations. Such details are routinely examined and incorporated into permits through the normal permitting process. Such details have been and continue to b e the subject of scrutiny by DEQ permitting staff in the ongoing PRGS permitting process.
T he PRGS permitting process has included many public comment opportunities for
citizens to examine and comment on the drafts.

In regard to specific concerns about P M 2.5 increases from the use of TRONA injection at PRGS, t he May 31, 2006, letter from Mr. Welsh to Congressman Moran provides an
enclosure that addresses the issue s of full scale evaluations of TRONA use and particulate increases due to TRONA injection. T he enclosure states, “EPA believes there is sufficient evidence that TRONA is a suitable absorbent for injection into a23 power plant flue gas stream for the purpose of removing sulfur dioxide. ... The Material Safety Data Sheet (MSDS) for TRONA identifies is as a relatively non

- toxic compound.
...” The enclosure also summarizes the effect of TRONA at PRGS as, “TRONA was
demonstrated to remove 80% of SO 2 emissions, while not impacting opacity and significantly decreasing the PM 10 emission rate.”

PM 2.5 t ests wer e performed using EPA’s Conditional Test Method 40 (CTM

- 40) at PRGS on December 14 through 17, 200 6 . These tests confirmed that TRONA injection
did not increase PM 2.5 emissions from the boilers.

22

. SUBJECT: PM 2.5 impacts of the PRGS in Alexandria, Virg inia

COMMENTER: Sierra Club

TEXT: PRGS is the single largest source of PM 2.5 in northern Virginia. PM 2.5 monitors at Marina Towers measured concentrations above the 35 μ g/m 3 24

- hour NAAQS on several occasions in 2007

. EPA scientists have recommende d an annual
PM 2.5 NAAQS limit t hat is lower than 15.0 μ g/m 3

. The City of Alexandria’s dispersion modeling to date, including downwash, demonstrates that a “hot spot” exists. PRGS contributes significantly to PM 2.5 nonattainment in Alexandria and the metr opolitan
Wa shington areas.

RESPONSE: While PRGS is indeed a large emitter of PM 2.5 , it is not the largest point source emitter in the metropolitan Washington area, nor is it the largest emitter in northern Virginia, when all segments of the point, area, non

- road, and transportation
inventor ies are considered.

As stated elsewhere , short

- term excursions above the 35 μ g/m 3 standard are not actionable violations. Violations are based on statistical methodologies to take into account exposure rates. Occasi onal exceedences of the 35 μ g/m 3 standard must be treated as data variability unless a violation of the PM 2.5 NAAQS occurs. Additionally, this attainment plan is designed to address the 1997 PM 2.5 NAAQS, which sets the
standards at 15 .0 μ g/m 3 on an annual average and 65 μ g/m 3 on a 24

- hour average. Since the NAAQS standard is based on three years of data, only a partial evaluation
can be made of the Marina Towers monitoring data. As previously noted , for January through December 2007, the Marina Towers mo nitor measured an annual average of
13.5 μ g/m 3 and a 24

- hour average of 31.3 μ g/m 3

. DEQ will continue to examine the data gathered from this monitoring site.

The purpose of this attainment plan is to address the 1997 standards as finalized.
These standa rds are 15.0 μ g/m 3 on a n annual average and 65 μ g/m 3 on a 24

- hour average. Certainly it is important to be mindful of the 2006 standard revision to 35

μ g/m 3 on a 24

- hour basis as well as other information such as scientific recommendations. However, this document, which shows that air quality has improved
and currently meets the 1997 standards at all FRM monitors and that air quality is predicted to meet the 2006 standards at all FRM monitors by 2009, is full y approvable24 as written.

See the response to c omment 21 for a discussion of “hot spot s .” As noted in the response to comment 10 , t he current EPA guidance for regional modeling to support attainment plans requires LAA s for areas within a region that show elevated monitored
PM 2.5 concentrations at moni tors within the federal reference monitoring network when compared to data from other federal reference monitors in the region. EPA does not, within the context of SIP attainment planning, have a definition for the term “hot spot.”
T he monitoring network shows similar results for various monitoring sites.

To ensure that PRGS is not causing a NAAQS violation, the attainment demonstration requires that an ambient air quality analysis of PRGS emissions be provided once such methodology is finalized. Alexan dria’s modeling exercise of PRGS emissions does not use a methodology that has been peer reviewed and finalized by EPA. The methodology may doublecount PRGS emissions since it adds background concentrations from nearby PM 2.5 FRMs even though PRGS, as an e xisting facility, contributes to these concentrations. The methodology adopted by Alexandria has been used by other states, but only for new and modified sources, not existing sources.
The refore , Alexandria’s methodology and results are inappropriate for inclusion in this
attainment demonstration.

23

. SUBJECT: Non

- road emissions.

COMMENTER: Metropolitan Washington Airports Authority

TEXT: The commenter requests confirmation that the attainment plan intends to account for airport construction equi pment emissions. Additionally, the commenter requests that construction emission budgets for airports can be derived from the plan as percentages of county construction equipment emissions, based on employment at the airports relative to county employment.

RESPONSE: County level construction emissions are intended to account for construction emissions at the airports as well as other facilities within each county. DEQ agrees that past methodologies have used a percentage of employment by the airport, as compared to county employment data, to demonstrate the inclusion of these emissions in the implementation plan. However, it is not appropriate to include this methodology in the attainment demonstration narrative. Future guidance from EPA may provide ot her acceptable ways in which to apportion these emissions so that inclusion in the attainment plan of any particular way may require a future SIP revision, a time and resource intensive process.

24

. SUBJECT: Corrections and clarifications.

COMMENTER: U.S. EPA

, Region III

TEXT: The plan must address both the annual and 24

- hour 1997 NAAQS25 standards; that much of the guidance for this plan is also relevant to both the annual
and 24

- hour standard; that the appropriate level of precision for the annual s tandard is
15.0 μ g/m 3

. C larifying language in regard to the status of the nonattainment area
emissions ca ps within the Virginia CAIR rule should be added; and that a typographical mistake was located in Section 9.3.1.

RESPONSE: These comments are accep table, and the proposal has been revised accordingly.

TEMPLATES \ SIP

- PLAN \ PLN03
SIP \ NONATTN PLANS \ 2008 \ NVApm

- SIP

- 3.DOC