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Ozone State Implementation Plan (SIP) Process
Moderate Area Ozone SIP

Overview

Within two years after setting or revising NAAQS for criteria pollutants, the EPA must designate areas as meeting (attainment) or not meeting (nonattainment) the air-quality standard. The EPA’s final designations are based on the most recent three years of air-quality monitoring data, recommendations from the state, and additional technical information. State recommendations are made by the governor and consider air-quality data, emissions, meteorology, topography, and jurisdictional boundaries.

If an area is not meeting the standard, the state is required to prepare a SIP. The SIP is a comprehensive document that identifies how the state will attain or maintain the NAAQS to comply with the provisions of the Clean Air Act. The SIP includes regulatory and non-regulatory control measures for reaching attainment by a specific deadline.

Marginal SIP Requirements

All or parts of seven Utah counties are currently designated as Marginal nonattainment, the least stringent nonattainment designation, for the 2015 8-hour ozone standard. These areas are required to attain the ozone standard by August 3, 2021. The Clean Air Act requires the following actions for areas designated as Marginal nonattainment:

  • A baseline emission inventory must be completed
  • A nonattainment new source review (NNSR) program must be implemented, with a NSR emission offset ratio of 1.1:1
  • Emission statements from sources with a threshold of 25 tons per year of NOx or VOCs must be completed

Moderate SIP Requirements

All or parts of seven Utah counties are currently designated as Marginal nonattainment for the 2015 8-hour ozone standard. Based on recent monitoring data, at this time, the DAQ expects that all nonattainment areas, with the exception of the Southern Wasatch Front nonattainment area, will not attain the ozone standard and will be bumped up to Moderate nonattainment in 2022. The Clean Air Act requires the following actions for areas designated as Moderate nonattainment:

  • All requirements for Marginal nonattainment as listed above, with a more stringent NSR emission offset ratio as listed below
  • A NNSR program must be implemented, with a NSR emission offset ratio of 1.15:1
  • A major source of VOCs/NOx reasonably available control technology (RACT) analysis must be completed
  • An attainment demonstration with 6 years to attain must be made
  • A 15% reduction in VOCs to demonstrate reasonable further progress (RFP) within 6 years must be implemented
  • A basic emissions inspection and maintenance (I/M) program must be implemented
  • Contingency measures for failure to attain must be determined
  • Stage II gasoline vapor recovery must be implemented

SIP Timeline

These are approximate deadlines that will be confirmed when EPA bumps Utah’s ozone nonattainment areas to moderate, which will most likely affect this schedule.

June 2018
Marginal SIP

Ozone Designations Effective

August 2020
Marginal SIP

2017 Emissions Inventory Due

July 2021
Marginal SIP

Emissions Inventory Modeling Finished

August 2021
Marginal SIP

Nonattainment New Source Review Due

February 2022
Moderate SIP

Redesignations to Moderate Ozone Nonattainment

September 2022
Moderate SIP

Draft SIP Document Proposed for Public Comment

February 2023
Moderate SIP

RACT/RACM And Moderate SIP Due

February 2024
Moderate SIP

RACT/RACM Implementation Deadline

August 2024
Moderate SIP

Moderate Ozone Attainment Date

Stakeholder Meetings

The DAQ wants to ensure an inclusive public involvement and stakeholder process and involve both industry and advocates for clean air. As DAQ staff progresses in the SIP process, public meetings will be held to provide information regarding regulatory timelines and the actions that DAQ will be obligated to take to meet the new requirements for a moderate classification, as well as provide an opportunity for questions regarding the SIP process. This section will be updated as public meetings are scheduled.