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On August 20, 2019, EPA published a final memorandum for Guidance on Regional Haze Sate Implementation Plans for the Second Implementation Period (Guidance), which is available on EPA's webpage. The guidance is intended to help state agencies prepare the State Implementation Plans (SIPs) that are due on or before July 31, 2021. These SIPs are to cover the second of the ten-year implementation periods (the second period is from 2019 to 2028) under the Regional Haze Rule (RHR) and must show reasonable progress towards the national goal of preventing future, and remedying existing, anthropogenic visibility impairment in the 156 Class I areas. Based on Trinity's experience during the first planning period (ending in 2018), “reasonable progress” is a somewhat subjective notion. The Guidance confirms this experience by stating that “there is no specific outcome or amount of emission reduction or visibility improvement that is directed as the reasonable amount of progress for any Class I area.”

Four Statutory Factor vs. Five Considerations

In general, each state must evaluate what emission control measures are reasonable for its own sources, groups of sources, and/or source sectors in light of the four statutory factors. In addition, states at their own discretion can include in their assessment the five additional considerations specified in the Regional Haze Rule, and possibly other considerations (e.g., visibility benefits of potential control measures, etc.). Techniques available for states to identify which sources to evaluate include emissions divided by distance (Q/d), trajectory analyses, residence time analyses, and photochemical modeling. Emissions can be defined on the basis of the sum of emissions of all visibility-impairing pollutants or could also be evaluated on a pollutant-by-pollutant basis. The direct and precursor pollutants that can impair visibility include sulfur dioxide (SO2), nitrogen oxides (NOx), fine and coarse particulate matter (PM), volatile organic compounds (VOC), and ammonia.

Once a state determines which sources to evaluate, evaluations are performed to determine what, if any, controls should be implemented at each source. The four statutory factors listed in 40 CFR 51.308(f)(2)(i) must be considered in this evaluation, while the five additional considerations listed in 40 CFR 51.308(f)(2)(iv) may be considered. These nine items are paraphrased below.

Four statutory factors from 40 CFR 51.308(f)(2)(i):

  1. Cost of compliance
  2. Time necessary for compliance
  3. Energy and non-air environmental impacts
  4. Remaining useful life of the source

Five additional considerations from 40 CFR 51.308(f)(2)(iv):

  1. Emission reductions due to ongoing air pollution control programs
  2. Measures to mitigate the impacts of construction activities
  3. Source retirement and replacement schedules
  4. Basic smoke management practices for prescribed fire
  5. The anticipated net effect on visibility due to projected changes in point, area, and mobile source emissions over the period

States have discretion to balance these factors and considerations in determining what control measures are necessary to demonstrate reasonable progress, as long as the SIPs are consistent with applicable regulations and “are the product of reasoned decision-making.” Despite the Guidance mentioning several times that other considerations may be involved, including specifically listing the visibility benefits of controls as an example, the analysis is referred to as a four-factor analysis.

Cost of Compliance Factor

EPA recommends expressing the cost of compliance in terms of a cost/ton of emissions reduction metric, with emission reduction on an annual basis. EPA recommends states place greater weight on vendor quotes that include a contract offer over quotes that do not. The second factor involves estimating the time needed for a source to comply with a potential control measure. The energy impacts portion of the third factor should focus on direct energy consumption at the source, typically evaluated in terms of kilowatt-hours or mass of fuels used, rather than indirect energy inputs such as the need to produce raw materials for the control equipment. The non-air environmental impacts portion include generation of wastes for disposals and impact on other environmental media such as nearby water bodies. For more details relevant to assessing non-air impacts, please review the collection of policies and guidance from the National Environmental Policy Act. The final statutory factor involves collecting information on how long the source will remain in operation and the lifetime of potential control measures, specifically considering any enforceable requirements to cease operation.

If you would like further information about the potential applicability of and considerations for a four-factor analysis at your facility, Trinity Consultants can offer technical expertise as well as practical experience to meet your organization's needs. Learn more about Trinity's Regional Haze Support services or call us at (800) 229-6655.