Interstate Transport/Ozone: Arkansas Department of Energy & Environment - Division of Environmental Quality Comments on U.S. Environmental Protection Agency SIP Disapproval

The Arkansas Department of Energy & Environment - Division of Environmental Quality (“DEQ”) submitted comments on April 22nd to the United States Environmental Protection Agency (“EPA”) on a proposed rule disapproving a state implementation plan (“SIP”).

See Docket No. EPA-R06-OAR-2021-0801.

EPA disapproved on February 22nd Arkansas’s SIP addressing interstate transport for the 2015 8-Hour Ozone National Ambient Air Quality Standards (“NAAQS”). See 87 Fed. Reg. 9798.

The states of Louisiana, Oklahoma, and Texas SIPs were also disapproved in the same Federal Register Notice.

EPA proposed a federal implementation plan (“FIP”) for Arkansas and 25 other states on April 6th. See 87 Fed. Reg. 20036.

By way of background, in 2015 EPA promulgated a revision to the 8-Hour NAAQS. The federal agency had lowered the level of both primary and secondary standards to 0.070 parts per million.

Air transport refers to pollution from upwind emission sources that impact air quality in a particular location downwind. The total pollution in any area forms from the combination of local and upwind sources. The transport of pollutants across state borders is often denominated “interstate air pollution transport.” Transport of interstate air pollution transport may in some cases affect downwind states’ ability to meet the NAAQS for ozone.

The Clean Air Act contains a “good neighbor” provision which requires that EPA and the states address interstate transport of air pollution that affects down states’ ability to attain and maintain NAAQS. Clean Air Act Section 110(a)(2)(B)(i)(l) requires that each state in its SIP prohibit emissions that will:

• Significantly contribute to nonattainment of NAAQS
• Interfere with maintenance of NAAQS in a downwind state

A state’s SIP must prohibit sources in that state from “emitting any air pollutant in amounts which will contribute significantly to nonattainment in, or interfere with maintenance of NAAQS in another state.” If EPA determines that an SIP is inadequate it must require that the state revise the SIP (i.e., a SIP call). A SIP call can be issued to multiple states at the same time. EPA may therefore issue a SIP call whenever it determines that the SIP is substantially inadequate to attain or maintain a particular NAAQS to ensure that the state’s sources do not contribute significantly to a downwind state’s nonattainment.

DEQ’s April 22nd comments on the February 22nd SIP disapproval provide a detailed rationale for reasons it believes the federal agency reached an incorrect conclusion. The agency notes in part that it is submitting the comments:

. . . in hopes of fostering a more cooperative relationship with EPA, and formally requests that EPA reevaluate Arkansas’s state plan based on the evidence presented therein and fully approve the plan, which satisfies good neighbor requirements as specified in the Clean Air Act.

The comments were submitted under the signature of David Witherow, P.E., who serves as DEQ’s Office of Air Quality Associate Director.

Besides the Introduction, Background, and Conclusion, DEQ’s comments include the following components:

• Timing of EPA’s Proposed Rule
• Modeling
• Interstate Transport Framework Step I: Identification of Downwind Air Quality Problems
• Interstate Transport Framework Step 2: Identifying Linkages
• Interstate Transport Framework Step 3: Identification and Evaluation of Air Quality, Upwind State Emission, and Cost Factors
• Evaluation of EPA Newly-Identified Linkages
• The Federal-State Partnership
• Conclusion
• Appendix A

Appendix A includes:

Figures and Tables in the DEQ comments include:

List of Figures

List of Tables

Table 1: Gross Load and Emission Rate from Oswald Generating Station

A copy of the DEQ comments can be found here and the February 22nd Federal Register Notice here.