Daily Rules, Proposed Rules, and Notices of the Federal Government
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 SO
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 SO
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),
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.
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 SO
The problems associated with high levels of SO
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 SO
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 SO
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 PM
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 SO
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 SO
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).
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.
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, New
Units 1, 2, and 5 utilize continuous emissions monitoring system (CEMS). In 2009, SO
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 SO
Other sources of SO
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.
Current scientific evidence links health effects with short-term exposure to SO
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 SO
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.
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 EPA
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.
The NJDEP petition asserts and presents modeling that demonstrates that emissions from one plant (the Portland Plant) by itself is sufficient to cause downwind SO
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 SO
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 SO
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 (
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 higher
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 SO
(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.
(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 SO
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 does
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 SO
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 SO
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 SO
NJDEP submitted two different modeling analyses of the SO
Table V.A-1 summarizes the CALPUFF and AERMOD 1-hour SO
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 SO
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 SO
The modeling submitted by NJDEP indicates actual emissions from the Portland Plant alone cause air quality in New Jersey to exceed the 1-hour SO
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.
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.
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.”
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:
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,”
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.
EPA issued a memo on August 13, 2008, providing “Clarification of Regulatory Status of CALPUFF for Near-field Applications,”
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,
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”
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) plots
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 SO
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.
As noted previously, NJDEP submitted dispersion modeling results based on maximum allowable emissions as well as actual emissions. For the reasons