September 20,2013 

Carol Kemker, Acting Director 

Georgia Department of Natural Resources 

Environmental Protection Division • Air Protection Branch 

4244 International Parkway • Suite 120 • Atlanta • Georgia 30354 

404/363-7000 • Fax: 404/363-7100 

Judson H. Turner, Director 

Air Pesticides and Taxies Management Division 

U.S. EPA, Region 4 

Atlanta Federal Center 

61 Forsyth Street, S.W. 

Atlanta, Georgia 30303 

Re: Clarification of Maintenance Plan Contingency Requirements 

Dear Ms. Kemker: 

On April 4, 2012, the Georgia Environmental Division (EPD) submitted to the U.S. 

Environmental Protection Agency (EPA) a redesignation request and maintenance plan 

for the Atlanta nonattainment area for the 1997 8-hour ozone National Ambient Air 

Quality Standard (NAAQS) for approval and incorporation into Georgia's State 

Implementation Plan (SIP). 

Recently, staff from EPA Region 4 requested that Georgia EPD provide additional 

clarification on the timing and content of the contingency measures identified in the 

maintenance plan for the Atlanta area. Georgia EPD is submitting this letter to provide 

further clarification of the contingency requirements found in the plan. 

The Atlanta maintenance plan includes Tier I and Tier II triggers which, if activated, will 

require EPD to take corrective actions to mitigate in accordance with the trigger. A Tier 

I trigger is activated when any quality-assured, 8-hour ozone monitoring reading 

exceeds 0.084 parts per million (ppm) or if the periodic emission inventory updates 

reveal excessive or unanticipated growth greater than 10 percent in emissions of either 

ozone precursor. A Tier II trigger is activated when any violation of the 8-hour ozone 

NAAQS at any of the monitoring stations is recorded based on quality-assured 

monitoring data. 

The purpose of this letter is to confirm that EPD commits to address and correct any 

violation of the 1997 8-hour ozone NAAQS as expeditiously as practicable and no later 

than 24 months from the trigger activation. Upon activation of a Tier I or II trigger, EPD 

will commence a comprehensive study of all available data to determine the cause of 

the exceedance or violation of the ozone NAAQS. The study will be completed as 

expeditiously as practicable, but no later than nine months after the trigger is activated. 

The study includes determining the cause of the monitor reading in excess of 0.084 

ppm or of the violation and any emissions control measures that may be necessary to 

prevent or correct, respectively, a violation of the NAAQS. Emissions from 
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Ms. Carol Kemker 

September 20, 2013 

Page Two 

implementation of previously adopted controls, which have not yet been realized and 

which are not relied upon in the maintenance demonstration, will be implemented within 

18 to 24 months. These emissions control measures, which were identified in EPD's 

maintenance plan, will produce substantial reduction of ozone precursors in excess of 

what was relied upon in the maintenance demonstration. These controls include 

Georgia's Multipollutant Rule and diesel engine retrofit, replacement and repowering 

programs. 

In the event that EPD's review and analysis concludes that the previously adopted 

emission control programs identified above and in the plan are not sufficient to address 

any violation of the NAAQS, EPD will adopt additional rules or controls to require further 

emissions reductions as identified in the plan. Any additional rules or controls to 

address a violation would be adopted and implemented within 18 - 24 months of the 

activation of a trigger. Any new rule will be submitted to EPA for approval into the 

State's SIP. 

In any event, if a Tier II trigger is activated, EPD, consistent with its commitment to EPA 

in the Air Planning Agreement, will consult and seek review from EPA on the analysis to 

determine the cause of the violation. EPD commits to develop a plan, then adopt and 

implement measures to correct the violation within 18 to 24 months of any violation of 

the NAAQS. 

If you have any questions or need more information, please contact Jimmy Johnston at 

(404) 363-7014 or via email at jimmy.johnston@dnr.state.ga.us. 

Sincerely, 

~~~-a 

Keith Bentley,~ Air Protection Branch 

KB:JK:klc 

c: Lynorae Benjamin, EPA Region 4 

Jimmy Johnston, Air Protection branch