thefederalregister.com

Daily Rules, Proposed Rules, and Notices of the Federal Government

ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-HQ-OAR-2011-0081; FRL-9291-2]

RIN 2060-AQ69

Response to Petition From New Jersey Regarding SO2Emissions From the Portland Generating Station

AGENCY: Environmental Protection Agency (EPA).
ACTION: Proposed rule.
SUMMARY: In this action, EPA proposes to make a finding that the coal-fired Portland Generating Station (Portland Plant) in Upper Mount Bethel Township, Northampton County, Pennsylvania, is emitting air pollutants in violation of the interstate transport provisions of the Clean Air Act (CAA or Act). Specifically, EPA is proposing to find that emissions of sulfur dioxide (SO2) from the Portland Plant significantly contribute to nonattainment and interfere with maintenance of the 1-hour SO2national ambient air quality standard (NAAQS) in New Jersey. This finding is proposed in response to a petition submitted by the State of New Jersey Department of Environmental Protection (NJDEP) on September 17, 2010. In this action, EPA is also proposing emission limitations and compliance schedules to ensure that the Portland Plant will no longer significantly contribute to nonattainment, and no longer interfere with maintenance of the 1-hour SO2NAAQS, thereby permitting continued operation of the Portland Plant beyond the 3-month limit established by the CAA for sources subject to such a finding.
DATES: Comments.Comments must be received on or before May 27, 2011.

Public Hearing:A public hearing will be held on April 27, 2011, in the Pequest Trout Hatchery and Natural Resources Education Center located in Oxford, Warren County, New Jersey 07863. Please refer toSUPPLEMENTARY INFORMATIONfor additional information on the comment period and the public hearing.

ADDRESSES: *http://www.regulations.gov.Follow the online instructions for submitting comments. Attention Docket ID No. EPA-HQ-OAR-2011-0081.

*E-mail: a-and-r-docket@epa.gov.Attention Docket ID No. EPA-HQ-OAR-2011-0081.

*Fax:(202) 566-9744. Attention Docket ID No. EPA-HQ-OAR-2011-0081.

*Mail:EPA Docket Center, EPA West (Air Docket), Attention Docket ID No. EPA-HQ-OAR-2011-0081, U.S. Environmental Protection Agency, Mailcode: 2822T, 1200 Pennsylvania Avenue, NW., Washington, DC 20460. Please include a total of 2 copies.Hand Delivery:U.S. Environmental Protection Agency, EPA West (Air Docket), 1301 Constitution Avenue, Northwest, Room 3334, Washington, DC 20004, Attention Docket ID No. EPA-HQ-OAR-2011-0081. Such deliveries are only accepted during the Docket's normal hours of operation, and special arrangements should be made for deliveries of boxed information.

Instructions.Direct your comments to Docket ID No. EPA-HQ-OAR-2011-0081. EPA's policy is that all comments received will be included in the public docket without change and may be made available online athttp://www.regulations.gov,including any personal information provided, unless the comment includes information claimed to be Confidential Business Information (CBI) or other information whose disclosure is restricted by statute. Do not submit information that you consider to be CBI or otherwise protected throughhttp://www.regulations.govor e-mail. Thehttp://www.regulations.govWeb site is an "anonymous access" system, which means EPA will not know your identity or contact information unless you provide it in the body of your comment. If you send an e-mail comment directly to EPA without going throughhttp://www.regulations.gov,your e-mail address will be automatically captured and included as part of the comment that is placed in the public docket and made available on the Internet. If you submit an electronic comment, EPA recommends that you include your name and other contact information in the body of your comment and with any disk or CD-ROM you submit. If EPA cannot read your comment due to technical difficulties and cannot contact you for clarification, EPA may not be able to consider your comment. Electronic files should avoid the use of special characters, avoid any form of encryption, and be free of any defects or viruses. For additional information about EPA's public docket, visit the EPA Docket Center homepage athttp://www.epa.gov/epahome/dockets.htm.

Docket.All documents in the docket are listed in thehttp://www.regulations. govindex. Although listed in the index, some information is not publicly available,e.g.,CBI or other information whose disclosure is restricted by statute. Certain other material, such as copyrighted material, will be publicly available only in hard copy. Publicly available docket materials are available either electronically inhttp://www. regulations.govor in hard copy at the Air and Radiation Docket and Information Center, EPA/DC, EPA West Building, Room 3334, 1301 Constitution Ave., NW., Washington, DC. The Public Reading Room is open from 8:30 a.m. to 4:30 p.m., Monday through Friday, excluding legal holidays. The telephone number for the Public Reading Room is (202) 566-1744, and the telephone number for the Air Docket is (202) 566-1742.

FOR FURTHER INFORMATION CONTACT: Mr. Todd Hawes (919-541-5591),hawes.todd@epa.gov,or Ms. Gobeail McKinley (919-541-5246),mckinley.gobeail@epa.gov,Air Quality Policy Division, Office of Air Quality Planning and Standards (C539-04), Environmental Protection Agency, Research Triangle Park, NC 27711.
SUPPLEMENTARY INFORMATION:

I. General Information A. Where can I get a copy of this document and other related information? B. What should I consider as I prepare my comments for EPA? C. How can I find information about a public hearing? D. How is the preamble organized? II. EPA's Proposed Decision on NJDEP's September 17, 2010 Section 126 Petition III. Background A. Section 126 of the Clean Air Act B. Summary of Section 126 Petitions Submitted by NJDEP 1. NJDEP's May 13, 2010 Petition 2. NJDEP's September 17, 2010 Petition C. EPA Extensions for Acting on the Section 126 Petitions D. Background on the Portland Plant and Its Surrounding Area E. Sulfur Dioxide and Public Health IV. EPA's Methodology for Making the Proposed Section 126 Finding for the Portland Plant A. EPA's Approach for Determining Whether To Make a Section 126 Finding for the Portland Plant 1. CAA Section 126(b) 2. EPA's Approach To Evaluating NJDEP's Section 126 Petition V. Summary and Assessment of the Modeling and Other Data Relevant to EPA's Finding A. Summary of the Modeling Submitted by NJDEP To Support the Petition B. EPA's Assessment of the Modeling Submitted by NJDEP 1. NJDEP's Model Selection a. CALPUFF Alternative Model Justification 2. Emissions and Source Characteristics 3. Meteorological Data 4. Receptor/Terrain Data 5. AERMOD Results C. Summary of NJDEP's Trajectory Analysis and the Columbia Lake Monitor VI. EPA's Decision on Whether To Make a Section 126 Finding or Deny the Petition VII. EPA's Proposed Remedy A. Quantification of the Emission Reductions Necessary To Eliminate the Portland Plant's Significant Contribution 1. Summary of EPA's Remedy Modeling for 1-Hour SO2NAAQS 2. Model Selection 3. Meteorological Data 4. Receptor/Terrain Data 5. Portland Plant Emissions and Source Characteristics 6. Identification of Background Concentration To Use in the Remedy Analysis 7. Summary of EPA's Modeling Results a. Calculation of Emissions Limits Based on Maximum Modeled Impacts From Units 1 and 2 Plus Background VIII. Proposed Emission Limits and Compliance Schedules A. Statutory Requirements for Sources for Which EPA Makes a Section 126(b) Finding B. Proposed Emission Limits C. Proposed Compliance Schedules D. Alternative Compliance Schedule IX. Statutory and Executive Order Reviews A. Executive Order 12866: Regulatory Planning and Review and Executive Order 13563: Improving Regulation and Regulatory Review B. Paperwork Reduction Act C. Regulatory Flexibility Act (RFA) D. Unfunded Mandates Reform Act E. Executive Order 13132: Federalism F. Executive Order 13175: Consultation and Coordination With Indian Tribal Governments G. Executive Order 13045: Protection of Children From Environmental Health and Safety Risks H. Executive Order 13211: Actions That Significantly Affect Energy Supply, Distribution, or Use I. National Technology Transfer and Advancement Act J. Executive Order 12898: Federal Actions To Address Environmental Justice in Minority Populations and Low-Income Populations II. EPA's Proposed Decision on NJDEP's September 17, 2010 Section 126 Petition

EPA is proposing to grant the request in NJDEP's September 17, 2010, section 126 petition for a finding that emissions from the Portland Plant significantly contribute to nonattainment or interfere with maintenance of the 1-hour SO2NAAQS in New Jersey. EPA's proposed finding is based on EPA's review of NJDEP's air quality modeling, EPA's independent assessment of the AERMOD1 dispersion modeling, andother technical analysis conducted by EPA.

1AERMOD stands for the American Meteorological Society/Environmental Protection Agency Regulatory Model.

In granting this request, EPA is also proposing to allow the continued operation of the plant and to establish specific emission limitations and compliance schedules (including increments of progress) to bring the plant into compliance as expeditiously as practicable with the CAA prohibition of emissions that significantly contribute to nonattainment or interfere with maintenance. EPA is proposing to require that the Portland Plant reduce its SO2emissions to a limit no greater than 1,105 lbs/hour for unit 1 and 1,691 lbs/hour for unit 2. EPA proposes that the Portland Plant achieve and maintain these emission limitations by no later than 3 years after the effective date of the final rulemaking. EPA is taking comment on possible interim emission reductions such as proposing that the Portland Plant reduce its SO2emissions to a level no greater than 2,910 lbs/hr for unit 1, and 4,450 lbs/hr for unit 2, one year after the effective date of the final rulemaking, and other compliance activities to demonstrate appropriate increments of progress toward compliance. EPA has identified a number of existing, proven control technologies, as well as operational changes that can be employed to reduce emissions from these units. Nevertheless, EPA is also taking comment on an alternative compliance option should the Portland Plant decide to cease operation at the units subject to the emission limits, and is requesting comment on appropriate timeframes and measures for increments of progress to include for that alternative compliance option. EPA proposes that the emission limits and other measures established along with this finding are sufficient to remedy the Portland Plant's significant contribution to nonattainment and interference with maintenance in the impacted area in New Jersey.

III. Background A. Section 126 of the Clean Air Act

The statutory authority for this action is provided by the CAA, including but not necessarily limited to, sections 126 and 110(a)(2)(D)(i).

Section 126(b) of the CAA provides, among other things, that any State or political subdivision may petition the Administrator of EPA to find that any major source or group of stationary sources in upwind States emits or would emit any air pollutant in violation of the prohibition of section 110(a)(2)(D)(i),2 which we describe later in detail. 42 U.S.C. 7426(b). Findings by the Administrator, pursuant to this section, that a source or group of sources emit air pollutants in violation of the section 110(a)(2)(D)(i) prohibition are commonly referred to as section 126 findings. Similarly, petitions submitted pursuant to this section are commonly referred to as section 126 petitions.

2The text of section 126 codified in the United States Code cross references section 110(a)(2)(D)(ii) instead of section 110(a)(2)(D)(i). The courts have confirmed that this is a scrivener's error and the correct cross reference is to section 110(a)(2)(D)(i),See Appalachian Power Co.v.EPA, 249 F.3d 1032, 1040-44 (DC Cir. 2001).

Section 126(c) explains the impact of a section 126 finding and establishes the conditions under which continued operation of a source subject to such a finding may be permitted. Specifically, section 126(c) provides that it would be a violation of section 126 of the Act and of the applicable State implementation plan: (1) For any major proposed new or modified source subject to a section 126 finding to be constructed or operate in violation of the prohibition of section 110(a)(2)(D)(i); or (2) for any major existing source for which such a finding has been made to operate more than three months after the date of the finding. 42 U.S.C. 7426(c). The statute, however, also gives the Administrator discretion to permit the continued operation of a source beyond three months if the source complies with emission limitations and compliance schedules provided by EPA to bring about compliance with the requirements contained in sections 110(a)(2)(D)(i) and 126 as expeditiously as practicable but no later than 3 years from the date of the finding.Id.

Section 110(a)(2)(D) of the CAA, often referred to as the “good neighbor” or “interstate transport” provision of the Act, requires States to prohibit certain emissions from in-State sources if such emissions impact the air quality in downwind States. Specifically, section 110(a)(2)(D) requires all States, within 3 years of promulgation of a new or revised NAAQS, to submit State implementation plans (SIPs) that: contain adequate provisions prohibiting any source or other type of emissions activity within the State from emitting any air pollutant in amounts which will contribute significantly to nonattainment in, or interfere with maintenance by, any other State with respect to any such national primary or secondary ambient air quality standard, or interfere with measures required to be included in the applicable implementation plan for any other State under part C to prevent significant deterioration of air quality or to protect visibility. (42 U.S.C. 7410(a)(2)(D)).

EPA has previously promulgated rules to quantify the specific SO2and nitrogen oxide (NOX) emission reductions required in certain eastern States by section 110(a)(2)(D)(i)(I) with respect to the NAAQS for ozone and fine particulate matter (PM2.5).See62 FR 57356 (NOXSIP Call); 70 FR 25162 (CAIR).3 EPA has also promulgated Federal rules to directly require such reductions.See71 FR 25318 [finalizing Federal Implementation Plans for Clean Air Interstate Rule (CAIR)]; 65 FR 2674 (making section 126 findings for numerous large EGUs and finalizing a remedy for the affected sources). Most recently, EPA proposed the Transport Rule to address significant contribution to nonattainment and interference with maintenance with respect to the 1997 ozone and the 1997 and 2006 PM2.5NAAQS (75 FR 45210). Among other things, this proposed rule identifies SO2and NOXreductions that will be needed in certain States to address PM2.5nonattainment and maintenance problems in other States.See75 FR 45129-21 (discussing the air quality problems and the specific NAAQS addressed by the proposal). SO2and NOXare identified as the pollutants of concern because of their impact on downwind States' ability to attain and maintain the PM2.5and ozone NAAQS.See75 FR 45237, 45299. SO2and NOXare PM2.5precursors and NOXis also an ozone precursor.

3CAIR was subsequently found unlawful and remanded to EPA without vacatur, and thus remains in place while EPA responds to the remand.See North Carolinav.EPA,531 F.3d 896, modified on reh'g, 550 F.3d 1176 (DC Cir. 2006).

The problems associated with high levels of SO2in the air, however, are separate and distinct from the problems associated with high levels of PM2.5and are addressed by a separate NAAQS, namely the 1-hour SO2NAAQS. 75 FR 35520 (Primary National Ambient Air Quality Standard for Sulfur Dioxide). The Transport Rule will not seek to identify or quantify reductions necessary to address significant contribution or interference with maintenance with respect to the 1-hour SO2NAAQS. In other words, the proposed Transport Rule does not address transport with respect to the 1-hour SO2NAAQS and thus does not address the concern raised in NJDEP's section 126 petition. Similarly, State 110(a)(2)(D)(i) SIP submissions relating to the ozone or PM2.5NAAQS would address only significant contribution to nonattainment and interference with maintenance of those NAAQS and thus would not address the concerns raisedregarding significant contribution to nonattainment and interference with maintenance of the 1-hour SO2NAAQS.

In addition, it is worth noting that the plain language of the statute confirms that section 126 remedies can, and in some cases must, be promulgated prior to the due date for good neighbor SIPs. Not only does section 126 provide a very stringent deadline for EPA to respond to section 126 petitions, but section 110(a)(2)(D)(ii) also calls for remedies promulgated pursuant to section 126 to be included in the SIP submissions that are due 3 years after a NAAQS is promulgated or revised. Section 110(a)(2)(D)(ii) requires State SIPs to contain adequate provisions “insuring compliance with the applicable requirements of [CAA section 126]”. 42 U.S.C. 7410(a)(2)(D). Consistent with the requirement in CAA section 110(a)(1), the Commonwealth of Pennsylvania will be required to adopt and submit to the Administrator, by June 2013 (3 years after the promulgation of the 1-hour SO2NAAQS), a SIP that satisfies the requirements of 110(a)(2) including the interstate transport requirements of 110(a)(2)(D)(ii). In other words, the statute requires the State SIP submittal to include any emission limits promulgated by EPA pursuant to section 126. The fact that Congress required the SIP submittals due 3 years after promulgation or revision of a NAAQS to include any emission limits promulgated pursuant to section 126 is meaningful. If Congress had intended to limit EPA's authority to act on section 126 petitions until after the deadline for States to submit 110(a)(2)(D)(i) SIPs, it could have done so. Instead, it provided a mechanism for section 126 remedies promulgated prior to the SIP submission deadline to be incorporated into the State SIPs. EPA is bound by the language of the CAA. Since the statute establishes firm deadlines for action on section 126 petitions, does not provide an exception for petitions submitted prior to the good neighbor SIP submission deadline, and provides a mechanism for incorporating reductions required in response to section 126 petitions into the State SIPs, EPA believes it does not have discretion to delay action on a section 126 petition just because the State SIP submission deadline has not yet passed. EPA requests comment on this interpretation and all interpretations of section 126 in this section.

EPA has received one prior petition, in 1979, asking for a section 126 finding with respect to a single source. In this petition, the Air Pollution Control District of Jefferson County, Kentucky, requested that EPA find, pursuant to the version of section 110(a)(2)(E)(I) of the CAA in effect at that time, that emissions from the Gallagher Power Station in southern Indiana were preventing attainment and maintenance with respect to the 1971 3-hour, 24-hour, and annual SO2NAAQS.4 47 FR 6624 (1982). The petition also sought a reduction of SO2emissions from the plant. EPA denied that petition basing its decision, in part, on a modeling analysis concluding that the Gallagher Power Station's modeled allowable emissions were substantially below amounts that would prevent attainment or maintenance of the NAAQS. In this proposal, EPA is also using modeling analyses to decide whether to make a section 126 finding or deny the petition. EPA's decision on the 1979 petition was upheld by the U.S. Court of Appeals for the Sixth Circuit.5

4Section 110(a)(2)(E)(i)(I) of the CAA was superseded by 110(a)(2)(D)(i)(I) in the 1990 CAA amendments, in part to strengthen the prohibitions of interstate transport of emissions (64 FR 28262). The relevant wording under 110(a)(2)(E)(i)(I) was changed from “prevent attainment or maintenance by any other State” to “contribute significantly to nonattainment in, or interfere with maintenance by, any other State” under 110(a)(2)(D)(i)(I).

5 SeeAir Pollution Control District of Jefferson County,Kentuckyv.EPA,739 F.2d 1071, (U.S. Court of Appeals, Sixth Circuit).

B. Summary of Section 126 Petitions Submitted by NJDEP 1. NJDEP's May 13, 2010 Petition

On May 13, 2010, EPA received from the NJDEP a section 126 petition requesting that EPA make a finding that the Portland Plant is emitting air pollutants in violation of the interstate transport provisions of the CAA. The petition alleges that emissions from the Portland Plant significantly contribute to nonattainment and/or interfere with maintenance of the 2006 24-hour PM2.5NAAQS and the 1971 3-hour and 24-hour SO2NAAQS in New Jersey. That petition is still under consideration and this action does not address the petition submitted on May 13, 2010.

2. NJDEP's September 17, 2010 Petition

On September 17, 2010, EPA received another section 126 petition from NJDEP requesting that EPA make a finding under section 126(b) of the CAA that the Portland Plant is emitting air pollutants in violation of the interstate transport provisions of the CAA with respect to the 1-hour SO2NAAQS promulgated on June 2, 2010 (75 FR 35520). NJDEP stated that this petition provided additional documentation to supplement the section 126 petition from May 13, 2010.

NJDEP also submitted a modeling and trajectory analysis to support the assertions in the September 17, 2010, petition. This analysis, it asserts, demonstrates that the Portland Plant causes violations of the 1-hour SO2NAAQS in Warren, Sussex, Morris, and Hunterdon Counties in New Jersey. NJDEP's petition asks EPA to directly regulate the Portland Plant and requests the installation of appropriate air pollution controls, such as a scrubber, which it asserts would provide the necessary abatement. As an alternative to address the alleged violations, NJDEP's petition suggests that the EPA could impose emission limits no less stringent than New Jersey's Reasonably Available Control Technology (RACT) rules set forth at N.J.A.C. 7:27-1.1et seq.

C. EPA Extensions for Acting on the Section 126 Petition

Any action taken by EPA under section 126 to make a finding or deny a petition is subject to the procedural requirements of CAA section 307(d).See42 U.S.C. 7607(d)(1)(N). One of these requirements is notice-and-comment rulemaking.See42 U.S.C. 7607(d)(3). In light of the time required for notice-and-comment rulemaking, CAA section 307(d)(10) provides for a time extension, under certain circumstances, for rulemaking subject to section 307(d).

In accordance with section 307(d)(10), EPA determined that the 60-day period afforded by section 126(b) for responding to the petition from the NJDEP was not sufficient to allow the public and EPA adequate opportunity to carry out the purposes of section 307(d). Specifically, EPA determined that the 60-day period was insufficient for EPA to develop an adequate proposal and allow time for notice-and-comment on whether the Portland Plant contributes significantly to nonattainment and/or maintenance problems in New Jersey. Based on these determinations, on November 16, 2010, EPA published a notice extending the deadline for action on the September 17, 2010, petition until May 16, 2011 (75 FR 69889). In this notice, EPA also explained its conclusion that the September 17, 2010, petition submitted by NJDEP is a new petition and not a supplement to the May 13, 2010, petition.

D. Background on the Portland Plant and Its Surrounding Area

The Portland Plant is a 427 megawatt (MW) coal-fired plant located in Upper Mount Bethel Township in Northampton County, Pennsylvania. It is within 500 feet of Knowlton Township in Warren County, NewJersey, directly across the Delaware River. There are two main units, unit 1 with a capacity of 160 MW and unit 2 with a capacity of 240 MW. There is an auxiliary boiler which burns oil and 3 small turbines (units 3, 4, and 5) which all burn oil and natural gas, and have very small emissions.

Units 1, 2, and 5 utilize continuous emissions monitoring system (CEMS). In 2009, SO2emissions combined from units 1 and 2 at the plant were 30,465 tons and emissions from unit 5 were 0.3 tons which are reported from CEMS data. Between 2007 and 2010, units 1 and 2 operated, on average, approximately 7,000 hours per year. Also, between 2007 and 2010, unit 5 operated for less than 100 hours per year.6

6Facility unit data is available at the EPA Clean Air Markets Division (CAMD) database available athttp://camddataandmaps.epa.gov/gdm/index.cfm?fuseaction=emissions.wizard.

The auxiliary boiler, unit 3, and unit 4 do not have CEMS, but emissions data are available from the 2008 National Emissions Inventory (NEI), Version 1. The auxiliary boiler, unit 3, and unit 4 SO2annual emissions reported in the 2008 NEI were 0.01, 0.02, and 0.03 tons, respectively.

Other sources of SO2emissions in the area include the Martins Creek facility which is located approximately 10 km to the south of the Portland Plant. There are two units at Martins Creek, units 3 and 4, which averaged about 1,039 and 584 hours of operation respectively. Those units each have a capacity of 850 MW and can burn either oil or natural gas. The facility reported approximately 1,100 tons of SO2emissions in 2009. There are also three cement plants (Hercules, Keystone, and ESSROC) and several minor emitting units in Pennsylvania located at distances generally greater than 30 km away to the south and west of the Portland Plant. In 2009, the Pennsylvania Department of Environmental Protection emission inventory database (PADEP eFACTS) reported 1,862 tons for Hercules, 685 tons for Keystone, and 799 tons for ESSROC of SO2emissions respectively, all of which are relatively low compared to the SO2emissions from the Portland Plant.

The Delaware River transects the region, with higher terrain on either side of the river valley where the Portland Plant is located. There is elevated terrain, as high as or greater than Portland's highest stacks, which rises 400 to 500 foot (ft) above the valley floor near the Portland Plant. The 1500 ft high Kittatinny Ridge is located within 7 kilometer (km) to the north and northwest of the Portland Plant. Further south, near the Martins Creek Power Plant, major terrain features such as Scotts Mountain to the east of the Delaware River rise up to 1000 ft above the valley floor.

E. Sulfur Dioxide and Public Health

Current scientific evidence links health effects with short-term exposure to SO2ranging from 5 minutes to 24 hours. Adverse respiratory health effects include narrowing of the airways which can cause difficulty breathing (bronchoconstriction) and increased asthma symptoms. These effects are particularly important for asthmatics during periods of faster or deeper breathing (e.g.,while exercising or playing). Studies show an association between short-term SO2exposure and increased visits to emergency departments and hospital admissions for respiratory illnesses particularly in at-risk populations including children, the elderly and asthmatics. EPA's NAAQS for 1-hour SO2is designed to protect against exposure to the entire group of sulfur oxides (SOX). SO2is the component of greatest concern and is used to represent the larger group of gaseous sulfur oxides. Other gaseous sulfur oxides (e.g.,SO3) are found in the atmosphere at concentrations much lower than SO2. Emissions that lead to high concentrations of SO2generally also lead to the formation of other SOX. Control measures that reduce SO2can generally be expected to reduce people's exposure to all gaseous SOX. Reducing SO2emissions is expected to have the important cobenefit of reducing the formation of fine sulfate particles that pose significant public health threats. SOXcan react with other compounds in the atmosphere to form small particles (e.g.,PM2.5). These small particles penetrate deeply into sensitive parts of the lungs and can cause or worsen respiratory disease, such as emphysema and bronchitis, and can aggravate existing heart disease, leading to increased hospital admissions and premature death.

IV. EPA's Methodology for Making the Proposed Section 126 Finding for the Portland Plant

This section explains the analysis conducted by EPA to determine whether it would be appropriate to find, in response to the petition submitted by NJDEP, that the Portland Plant emits or would emit any air pollutant in violation of the prohibition of section 110(a)(2)(D)(i)(I) with respect to the 1-hour SO2NAAQS.

A. EPA's Approach for Determining Whether To Make a Section 126 Finding for the Portland Plant 1. CAA Section 126(b)

Section 126 of the CAA provides a mechanism for States and other political subdivisions to seek abatement of pollution in other States that may be affecting their air quality; however, it does not identify specific criteria or a specific methodology for the Administrator to apply when deciding whether to make a section 126 finding or deny a petition. Therefore, EPA has discretion to identify relevant criteria and develop a reasonable methodology for determining whether a section 126 finding should be made.See, e.g., Chevron, U.S.A., Inc.v.NRDC,467 U.S. 837, 842-43 (1984);Smileyv.Citibank,517 U.S. 735, 744-45 (1996).

As an initial matter, EPA looks to see whether a petition identifies or establishes a technical basis for the requested section 126 finding. EPA first evaluates the technical analysis in the petition to see if that analysis, standing alone, is sufficient to support a section 126 finding. EPA focuses on the analysis in the petition because the statute does not require EPA to conduct an independent technical analysis to evaluate claims made in section 126 petitions. The petitioner thus bears the burden of establishing, as an initial matter, a technical basis for the specific finding requested. EPA has no obligation to prepare an analysis to supplement a petition that fails, on its face, to include an initial technical demonstration. Such a petition, or a petition that fails to identify the specific finding requested, could be found insufficient. Nonetheless, the Agency may decide to conduct independent technical analyses when such analyses are helpful in evaluating the basis for a potential section 126 finding or developing a remedy if a finding is made. As explained later, given our view that it is necessary to make some technical adjustments to the NJDEP modeling, we determined that it was appropriate to conduct independent technical analysis to determine an appropriate remedy. Such analysis, however, is not required by the statute and may not be necessary or appropriate in other circumstances.

In this section, EPA explains the methodology used to evaluate the technical analysis presented in NJDEP's petition and to determine whether it would be appropriate to make the section 126 finding requested. This methodology was developed to address the specific allegations in the NJDEP petition and does not speak to how EPAmight evaluate petitions that raise different interstate transport issues, such as collective contributions from multiple sources, contributions to nonattainment areas in multiple States, or contributions to different NAAQS. The methodology used to assess the remedy is discussed in section VII.

2. EPA's Approach To Evaluating NJDEP's Section 126 Petition

Emissions from upwind States can, alone or in combination with local emissions, result in air quality levels that exceed the NAAQS and jeopardize the health of residents in downwind communities. Each State is required by section 110(a)(2)(D)(i)(I) to prohibit emissions from activities within that individual State that would significantly contribute to downwind nonattainment or interfere with downwind States' maintenance of the NAAQS.

Section 110(a) of the CAA assigns to each State both the primary responsibility for attaining and maintaining the NAAQS within such State, and prohibiting emissions activities within the State that will significantly contribute to nonattainment or interfere with maintenance in a downwind area. States fulfill these CAA obligations through the SIP process described in section 110(a) of the CAA. States are required to submit SIPs to prohibit those emissions that significantly contribute to nonattainment or interfere with maintenance in downwind States within 3 years of promulgation of a new or revised NAAQS.See42 U.S.C. 7410(a), 7410(a)(2)(D). The prohibition on these emissions is intended to assist the downwind State as it designs strategies for ensuring that the NAAQS are attained and maintained.

The NJDEP petition asserts and presents modeling that demonstrates that emissions from one plant (the Portland Plant) by itself is sufficient to cause downwind SO2NAAQS violations in New Jersey. The approach described later was developed by EPA to analyze these specific claims in these particular circumstances and may not be appropriate for evaluating other claims or those arising in different circumstances for other actions.

In this case, EPA is proposing to define the Portland Plant's significant contribution to nonattainment and interference with maintenance as those emissions that must be eliminated to bring the downwind receptors in New Jersey affected by the Portland Plant into modeled attainment in the analysis year. While this approach would not be appropriate in every circumstance, EPA believes it is appropriate where, as here, the source's emissions are sufficient on their own to cause downwind NAAQS violations and background levels of the relevant pollutant are relatively low. EPA therefore developed a methodology to identify the reductions necessary to bring the downwind receptors into attainment.

EPA's methodology uses dispersion modeling to assess the impact of emissions from the Portland Plant on SO2concentrations at downwind receptors. EPA modeled the emissions from the Portland Plant and determined that the modeled concentrations from the Portland Plant, when combined with the relatively low background concentrations [in the manner described in section VII and in greater detail in the Modeling Technical Support Document (TSD)], cause violations of the 1-hour SO2NAAQS in New Jersey. We have determined it is appropriate to use modeling in this case to determine whether downwind air quality will attain the 1-hour SO2NAAQS in the analysis year.7

7Historically, EPA has favored dispersion modeling to support SO2NAAQS compliance determinations for areas with sources that have the potential to cause an SO2NAAQS violation, and EPA explained that for an area to be designated as “attainment,” dispersion modeling regarding such sources needs to show the absence of violations even if monitoring does not show a violation. This has been our general position throughout the history of implementation of the SO2NAAQS program.See75 FR 35551.

In the modeling analysis, thousands of receptors are placed in New Jersey to determine the area of maximum concentration from the Portland Plant emissions. A design value concentration is calculated for each receptor for comparison to the NAAQS. The design value concentration is equal to the 99th percentile (4th-highest) daily maximum 1-hour SO2concentration. All receptors with modeled design value concentrations that are greater than the NAAQS (196 μg/m3) are determined to be nonattainment receptors.

To quantify the emissions that constitute the Portland Plant's significant contribution, we identify the level of emissions that need to be reduced to ensure that no modeled concentration within the affected area exceeds the level of the NAAQS (i.e.,the 99th percentile of the daily maximum 1-hour average of 196 μg/m3).

The first step of the “interfere with maintenance” analysis is to identify whether there are any maintenance receptors in the relevant area. In considering maintenance, we are examining the receptors in the analysis to determine if higher modeled concentrations may exist due to variability in meteorology, emissions, and/or other factors. Nonattainment receptors are already modeled to be above the NAAQS and receptors with higher8 concentrations attributed to variability in emissions or meteorology would be exceeding the NAAQS by an even greater amount. Therefore, nonattainment receptors are by definition also maintenance receptors. In addition to these nonattainment/maintenance receptors, we also examine receptors that are modeled to be attainment but due to variability in meteorology or emissions might be at risk for nonattainment. In that case, any identified maintenance receptors would not be nonattainment and would therefore be considered “maintenance only” receptors.

8Variability of emissions and meteorology could also lead to lower concentrations; however, for purposes of identifying interference with maintenance receptors, we would only be concerned with concentrations that would be higher than those modeled.

In this particular case, due to the high modeled concentrations from the Portland Plant emissions, all of the downwind modeled receptors in the modeled receptor grid in New Jersey are modeled to be nonattainment. In this application, it was not necessary to expand the modeling grid to identify additional nonattainment or “maintenance only” receptors because the modeling domain was centered on the receptors with the maximum impact from the Portland Plant. In a primary pollutant dispersion modeling application, emissions reductions from the contributing source lead to a linear reduction in downwind concentrations. Therefore, we can be certain that an emissions limit on the Portland Plant that eliminates modeled violations at the maximum concentration receptor will eliminate violations at all potential receptors. Because there are no “maintenance only” receptors in the area of concern, it was not necessary for us to consider the Portland Plant's impact on maintenance only receptors.

We next consider whether the Portland Plant should be required to make additional reductions, above and beyond those required to eliminate its significant contribution to nonattainment to ensure that it does not interfere with maintenance at the nonattainment/maintenance receptors. We identified an approach that we believe is appropriate for the specific circumstances presented here.

Among other things, we considered the nature of the modeling used to determine the appropriate remedy and the potential for SO2concentrations in New Jersey to be higher than thosemodeled. Here are some of the relevant facts:

(1) There is only 1 year of site-specific meteorology available for this analysis, so we are not able to examine the impact of year-to-year variability of meteorology on downwind modeled concentrations.9

9Due to constraints on data availability, our analysis is appropriate in this instance; however, nothing here is intended to suggest that, where sufficient data are available to examine year-to-year variability, this should not be a relevant factor.

(2) The remedy modeling used allowable emissions from the Portland Plant. Since these are the highest emissions that are allowed to be emitted by the facility, higher concentrations could not be expected to occur in New Jersey due to the emissions from the Portland Plant.

(3) In the modeling analysis, we used a seasonal and hourly varying background concentration that represents the high end of the distribution (99th percentile) of hourly observed SO2concentrations in the area. As indicated in the trajectory analysis submitted by NJDEP, it is likely that direct SO2impacts from the Portland Plant contributed to high monitored concentrations at the monitor located in Chester, New Jersey (Chester monitor). Therefore, to avoid double counting of contributions from the Portland Plant through both monitored and modeled emissions, it would not be appropriate to consider higher background concentrations.

EPA believes that given the specific circumstances described previously, there is no indication that concentrations higher than those modeled from the Portland Plant would be likely to occur at the nonattainment/maintenance receptors or anywhere in New Jersey. It is therefore reasonable to conclude, under the circumstances, that any remedy that eliminates the significant contribution to nonattainment from the Portland Plant will also eliminate its interference with maintenance with respect to year-to-year variability in emissions and air quality.

As noted in the proposed Transport Rule, EPA believes that the maintenance concept has two components: Year-to-year variability in emissions and air quality, and continued maintenance of the air quality standard over time. Consistent with the approach in the Transport Rule, EPA examined both of these concepts in assessing “interfere with maintenance” for NJDEP's section 126 petition regarding the Portland Plant. Year-to-year variability is discussed above. Year-to-year variability is appropriate to consider because data demonstrates that year-to-year variations in air quality that stem from differences in weather and emissions can determine whether or not the health-based standard will be achieved in a particular location in the analyzed year.

EPA separately considered whether further emissions reductions from the Portland Plant are necessary to ensure continued lack of interference with maintenance of the NAAQS over time, and believes that the answer is no. The proposed requirements of this rule will prevent the emissions of the Portland Plant from increasing over time relative to the modeled scenario. Also, EPA doesnothave evidence that background SO2emissions from other sources affecting the relevant New Jersey receptors will increase in the future, which—in combination with residual Portland Plant emissions—in theory might have raised the possibility of a future maintenance issue at those receptors.

In conclusion, we are proposing to find that compliance by the Portland Plant with the emission limits proposed in this action will bring it into compliance with the prohibition on emissions that significantly contribute to nonattainment of the 1-hour SO2NAAQS as well as with the prohibition on emissions that interfere with maintenance in a downwind area.

EPA requests comment on our approach to address interference with maintenance with regard to this specific petition and whether the proposed emission limits are sufficient to eliminate the Portland Plant's interference with maintenance of the 1-hour SO2NAAQS in New Jersey.

V. Summary and Assessment of the Modeling and Other Data Relevant to EPA's Finding A. Summary of the Modeling Submitted by NJDEP To Support the Petition

NJDEP submitted several technical analyses in support of its section 126 petition. Among the submitted materials were a summary of the NJDEP dispersion modeling results, a modeling analysis for the 1-hour SO2NAAQS using AERMOD, a modeling analysis for the 1-hour SO2NAAQS using CALPUFF,10 and a trajectory analysis of high SO2episodes at a SO2monitor in Chester, New Jersey. In addition, the petition references a CALPUFF model validation study, which was submitted by NJDEP along with the previous (May 13, 2010) section 126 petition.

10CALPUFF is a non-steady-state puff dispersion model that was originally developed for the California Air Resources Board.

11NJDEP did not add background concentrations to any of the modeled concentrations in the table.

12Meteorological data used in the AERMOD modeling was based on the only site-specific meteorological data available for the Portland Plant, from July 1993 through June 1994, which satisfies the recommendations in Section 8.3.1 of Appendix W regarding the length of record for meteorological data.

NJDEP submitted two different modeling analyses of the SO2impacts from the Portland Plant on New Jersey. The first analysis (Exhibit 2 to the NJDEP petition) used the AERMOD dispersion model and the second analysis (Exhibit 3 to the NJDEP petition) used the CALPUFF dispersion model. Both models were run with both actual and allowable emissions rates and CALPUFF was also run with various meteorological input data. Each NJDEP model run showed modeled violations of the 1-hour SO2NAAQS (i.e.,showed annual 99th percentile of daily maximum 1-hour SO2values at or above 196 μg/m3) in New Jersey.

Table V.A-1 summarizes the CALPUFF and AERMOD 1-hour SO2NAAQS (196 μg/m3, 99th percentile) modeling results submitted by NJDEP.

Table V.A-1—Summary of Modeling Results Submitted by NJDEP Model Emissions Meteorology Maximum modeled
  • concentration
  • (μg/m3)
  • 99th Percentile (4th high) modeled
  • concentration
  • (μg/m3)11
  • AERMOD Allowable July 1993-June 199412 3,700 1,402 AERMOD Estimated Actual July 1993-June 1994 1,713 467.3 CALPUFF Allowable 2002 12km MM5 15,273 3,455 CALPUFF Actual 2002 12km MM5 6,740 2,194 CALPUFF Allowable 2003 4km MM5 18,643 2,468

    As can be seen in the table V.A-1, each of the modeling analyses submitted by NJDEP shows modeled violations of the 1-hour SO2NAAQS. The concentrations predicted by the CALPUFF model tend to be higher than those predicted by the AERMOD model. In addition, the model runs based on allowable emissions logically show higher concentrations than those based on actual emissions. The allowable emissions included in the NJDEP modeling are shown in Table V.A-2.

    Table V.A-2 Portland Plant unit Allowable SO2rate
  • (lb/hr)
  • Maximum 3-hr
  • permit limit (tons per 3 hours)
  • 1 5,820 8.73 2 8,900 13.35

    The petition also contained modeling of actual emissions for the 2002 MM5 (mesoscale meteorological model) based CALPUFF case and this modeling run showed large exceedances of the 1-hour SO2NAAQS. Actual emissions were also modeled with AERMOD for the 1993-1994 site-specific meteorology. As with the modeling based on allowable emissions, the AERMOD results with actual emissions were much lower than the CALPUFF results, but still showed significant exceedances of the 1-hour SO2NAAQS. The 2002 CALPUFF modeling with actual emissions was based on actual SO2emissions from CEMS data. The 1993-1994 actual emissions used with AERMOD were estimated based on monthly coal usage reports (CEMS data were not available for that period).

    The modeling submitted by NJDEP indicates actual emissions from the Portland Plant alone cause air quality in New Jersey to exceed the 1-hour SO2NAAQS. The NJDEP modeling also indicates that the Portland Plant's allowable emissions (i.e.,the emissions the plant would emit if it were to emit at the level currently allowed) cause air quality in New Jersey to exceed the 1-hour SO2NAAQS. The NJDEP AERMOD predictions of the 4th high daily 1-hour maximum concentrations (99th percentile) based on allowable emissions show a maximum concentration in New Jersey of 1,402 μg/m3(located on a ridge at the Delaware Water Gap (in New Jersey) approximately 7 kilometers (km) from the Portland Plant stacks). The AERMOD modeling submitted by NJDEP also demonstrates that actual emissions from the Portland Plant are causing NAAQS exceedances in New Jersey. In addition, the CALPUFF predictions of the 4th high daily maximum 1-hour concentrations (99th percentile) based on allowable emissions are as high as 3,455 μg/m3.

    The results of the NJDEP modeling based on both allowable and actual emissions indicate that emissions reductions would be needed at the Portland Plant in order to eliminate Portland's significant contribution to nonattainment in New Jersey.

    B. EPA's Assessment of Modeling Submitted by NJDEP

    EPA evaluated several aspects of the NJDEP modeling to determine if the analyses followed EPA regulations and guidance for dispersion modeling. Among the key specific issues evaluated were the choice of model(s), modeling of actual vs. allowable emissions, and the application of site-specific meteorological data that were used as inputs to the AERMOD model. Additional technical details regarding the NJDEP modeling were also examined, as documented in the Modeling TSD.

    1. NJDEP's Model Selection

    EPA first evaluated which model is most appropriate for use in these particular circumstances. As noted previously, NJDEP submitted both AERMOD and CALPUFF model results. Given the significant differences in the magnitude of predicted impacts associated with the Portland Plant emissions based on the use of the AERMOD model versus use of the CALPUFF model, identifying the most appropriate model for use in these circumstances was a key aspect of EPA's assessment. Section 4.2.2(b) of the “Guideline on Air Quality Models,” published as Appendix W to 40 CFR Part 51 (commonly referred to as “Appendix W”) States that AERMOD is “the recommended model” “[f]or a wide range of regulatory applications in all types of terrain.”13 The modeling application under consideration in this section 126 petition is covered under this section of Appendix W since the transport distances of concern are less than 50 kilometers.

    13Section 4.2.2 identifies other models that are recommended for specific applications that do not apply for the Portland Plant,e.g.,the Buoyant Line and Point Source (BLP) dispersion model is recommended for cases where buoyant plume rise from line sources is important.

    The NJDEP petition acknowledges that AERMOD is the preferred model for near-field applications such as this, but suggests the use of CALPUFF may be appropriate under the alternative model provisions in Section 3.2.2b of Appendix W. Section 3.2 of Appendix W lists three separate conditions under which an alternative model may be approved for use, as follows:

    (1)If a demonstration can be made that the model produces concentration estimates equivalent to the estimates obtained using a preferred model;

    (2)If a statistical performance evaluation has been conducted using measured air quality data and the results of that evaluation indicate the alternative model performs better for the given application than a comparable model in Appendix A; or

    (3)If the preferred model is less appropriate for the specific application, or there is no preferred model.

    The NJDEP modeling documentation suggests that NJDEP's use of the CALPUFF model in support of this petition is based on condition (2) of Section 3.2.2b. NJDEP claims that CALPUFF was shown to have “performed better and produced predictions of greater accuracy than AERMOD,”14 and therefore satisfies condition (2) under Section 3.2.2b of Appendix W. NJDEP also claims that the use of CALPUFF is more appropriate for the specific application due to the complex winds addressed in Section 7.2.8 of Appendix W15 and is therefore justified under condition (3) of Section 3.2.2b.

    14 SeeSeptember 17, 2010 petition, Section IV, page 5.

    15 SeeMay 13, 2010, petition, Section V, subsection B.

    For the reasons stated later, EPA determines that AERMOD is the appropriate modeling platform to use in these specific circumstances. This conclusion is based on the particular circumstances presented here and does not speak to whether it would be appropriate to use CALPUFF modeling in other situations.

    a. CALPUFF Alternative Model Justification

    EPA issued a memo on August 13, 2008, providing “Clarification of Regulatory Status of CALPUFF for Near-field Applications,”16 (which applies to the application under review here). The key points emphasized in that memo are as follows:

    16“Clarification of Regulatory Status of CALPUFF for Near-field Applications,” memo from Richard A. Wayland, dated August 13, 2008, available athttp://www.epa.gov/ttn/scram/clarification%20of%20regulatory%20status%20of%20calpuff.pdf.

    1. The EPA-preferred model for near-field regulatory applications (less than 50 kilometers) for simple and complex terrain is AERMOD. The AERMOD model should be used for all near-field regulatory applications, unless an adequate determination is made that AERMOD is not appropriate for that application or is clearly less appropriate than an alternative model.

    2. CALPUFF is not the EPA-preferred model for near-field applications, but may be considered as an alternative model on a case-by-case basis for near-field applications involving “complex winds,” subject to approval by the reviewing authority. The approval of CALPUFF for near-field regulatory applications must be based on case-specific justification, including necessary documentation and an adequate determination that AERMOD is not appropriate or clearly less appropriate than CALPUFF.

    The impacts from a source such as the Portland Plant (tall stacks with nearby terrain features) are likely to occur with “line-of-sight” impacts of the elevated plumes on nearby terrain features for which straight-line, steady-state assumptions are valid.

    The AERMOD model has been evaluated for similar situations of tall stacks in complex terrain settings for at least five separate data bases and consistently shown to perform better than competing models (Perry,et al.,2005;17 EPA, 200318 ). Therefore, EPA does not agree with the argument that CALPUFF is more appropriate in this situation due to the existence of complex winds.

    17Perry, S.G., A.J. Cimorelli, R.J. Paine, R.W. Brode, J.C. Weil, A. Venkatram, R.B. Wilson, R.F. Lee, and W.D. Peters, 2005. AERMOD: A Dispersion Model for Industrial Source Applications. Part II: Model Performance against 17 Field Study Databases.J. Appl. Meteor.,44, pp. 694-708.

    18EPA, 2003. AERMOD: Latest Features and Evaluation Results. EPA-454/R-03-003. U.S. Environmental Protection Agency, Research Triangle Park, NC, available athttp://www.epa.gov/scram001/7thconf/aermod/aermod_mep.pdf.

    We thus turn to NJDEP's assertion that the use of CALPUFF as an alternative model can be justified under condition (2) of Section 3.2.2b, based on a demonstration that CALPUFF performs better than AERMOD. To evaluate this assertion, we evaluate whether there is evidence to support NJDEP's assertion that CALPUFF performs better than AERMOD. In the September 17, 2010, petition, NJDEP references a CALPUFF validation study that was submitted with the May 13, 2010, petition. EPA believes it is appropriate to consider this study because it was explicitly referenced in the September 17, 2010, petition, and a copy was provided with the prior petition.

    We note again that the AERMOD model has undergone extensive peer review and model validation as the basis for its promulgation as the preferred model for a wide range of regulatory applications in all types of terrain. Therefore, we would not determine CALPUFF to be a more appropriate model in this case absent compelling evidence that CALPUFF is clearly superior to AERMOD for this application.

    Model validation is a complex process that entails several technical challenges, including uncertainties regarding the accuracy and representativeness of key input data that could affect results, as well as a wide range of statistical methods and metrics that may be applied to quantify model performance. In some cases subtle changes to the evaluation methods can markedly affect the conclusions that might be drawn from such studies. For these reasons, the importance of establishing a consistent set of objective procedures to evaluate the performance of dispersion models for use in regulatory modeling applications and of comparing the relative performance of competing models has long been recognized. Section 3.2.1 of Appendix W references EPA's “Protocol for Determining the Best Performing Model”19 document (EPA, 1992) that states it “is available to assist in developing a consistent approach when justifying the use of other-than-preferred modeling techniques recommended in the Guideline. The procedures in this protocol provide a general framework for objective decision-making on the acceptability of an alternative model for a given regulatory application.

    19“Protocol for Determining the Best Performing Model”, EPA-454/R-92-025, December 1992. U.S. Environmental Protection Agency, Research Triangle Park, NC, available athttp://www.epa.gov/ttn/scram/guidance/guide/modleval.zip.

    Although the CALPUFF validation study submitted by NJDEP with the May 13, 2010, petition cites EPA's Protocol as one of the references for its model validation procedures, there were some key changes implemented in the NJDEP model evaluation study relative to the methods recommended and used by EPA in its evaluation of AERMOD model performance. EPA's evaluation of NJDEP's changes to the protocol leads us to believe that the NJDEP methods show relatively better model performance for CALPUFF compared to AERMOD, without any clear technical basis that would justify those changes. Further details on these changes and their impacts on the results of the validations study are provided in the Modeling TSD included in the docket for this rulemaking.

    Furthermore, the Quantile-Quantile (Q-Q) plots20 included in the NJDEP validation report provide a clear visual representation of model performance that is very relevant to the regulatory application of these models. These plots suggest that the performance of theCALPUFF and AERMOD models on this database is in fact quite similar, but that AERMOD shows slightly better overall agreement with observations.

    20Quantile-Quantile (Q-Q) plots compare modeled vs. monitored concentrations on the basis of independently ranked distributions of concentration, unpaired in time and space.

    Another fundamental point in relation to NJDEP's overall justification for the use of CALPUFF in this petition is that results from the model validation study are not relevant to this application of CALPUFF due to fundamental differences in the meteorological processing used in the validation study compared to the modeling submitted in support of the petition. The CALMET modeling for the validation study made use of the site-specific meteorological data collected as part of the field study so that the documented CALPUFF model performance is largely dependent on the characterization of wind fields by CALMET that are informed by that site-specific data. In contrast, the application of CALPUFF to support the petition did not use any site-specific meteorological data but relied on three different sets of MM5 prognostic meteorological data to inform the 3-dimensional wind fields generated by CALMET. Performance of the CALPUFF model in this case would rely upon the ability of the CALMET meteorological model to adequately simulate the wind fields in the absence of such site-specific data, and there have not been any such demonstrations that would be relevant to this application.

    We also note that the spatial distribution of 1-hour SO2impacts predicted by CALPUFF (in the petition application) is very different than the impacts predicted by AERMOD. The CALPUFF modeling shows extremely high 1-hour SO2concentrations very close to the Portland Plant (see Figures 1, 2, and 3 of Exhibit 3). The highest impacts based on the 2002 CALPUFF modeling with allowable emissions of 3,455 μg/m3(99th percentile of daily maximum 1-hour values) occurs about 100 meters from units 1 and 2 at an elevation of only 3 meters above the stack base in Pennsylvania. These results are physically unrealistic for buoyant plumes from tall stacks such as units 1 and 2 at the Portland Plant, raising additional concerns regarding the appropriateness of CALPUFF for this application.

    Based on the discussion previously (and additional details contained in the Modeling TSD), we conclude that NJDEP has not adequately justified the use of CALPUFF in this application under either conditions (2) or (3) of Section 3.2.2b of Appendix W, and that AERMOD is the most appropriate model for this application.21

    21EPA's discussion of the appropriate air quality model for near field applications focuses on primary emissions from a stationary source, such as the SO2emissions from the Portland Plant, at issue in NJDEP's petition. EPA is not suggesting that AERMOD is the appropriate model to simulate the effects of SO2and nitrogen oxide emissions on secondary pollutants formed in the atmosphere such as PM2.5and ozone.See70 FR 68,234.

    2. Emissions and Source Characteristics

    As noted previously, NJDEP submitted dispersion modeling results based on maximum allowable emissions as well as actual emissions. For the reasons