September 23, 2013 

Georgia Department of Natural Resources 

Environmental Protection Division • Air Protection Branch 

4244 International Pari<V)Iay • Suite 120 • Atlanta • Georgia 30354 

404/363-7000 • Fax: 404/363-7100 

Judson H. Turner, Director 

Carol Kemker, Acting Director 

Air Pesticides and Toxics Management Division 

U.S. EPA, Region 4 

Atlanta Federal Center 

61 Forsyth Street, S.W. 

Atlanta, Georgia 30303 

Re: Clarification of PM2.s Maintenance Plan Contingency Requirements 

Dear Ms. Kemker: 

In 2012 the Georgia Environmental Division (EPD) submitted to the U.S. Environmental 

Protection Agency (EPA) redesignation requests and maintenance plans for four 

Georgia areas that had been designated nonattainment for the 1997 Annual PM2.5 

National Ambient Air Quality Standard (NAAQS) for approval and incorporation into 

Georgia's State Implementation Plan (SIP). The four nonattainment areas, with their 

submittal dates, are as follows: 

• Floyd County 

• Macon 

• Atlanta 

• Chattanooga 

June 21, 2012 

June 21, 2012 

August 30, 2012 

September 14, 2012 (Georgia counties- Catoosa and Walker) 

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

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

maintenance plans. Georgia EPD is submitting this letter to provide further clarification 

of the contingency requirements found in the plans. Note that the contingency 

measures are identical in each of the plans. 

The plans include 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 1 trigger is activated 

when any one of the following conditions occurs: 
Ms. Carol Kemker 

September 23, 2013 

Page Two 

• the previous calendar year's annual average PM2.s concentration exceeds the 

standard by 1 .5 ug/m3 or more; 

• the annual average PM2.s concentration in each of the previous two 

consecutive calendar years exceeds the standard by 0.5 ug/m3 or more; 

• the total maintenance area S02 emissions in the most recent NEI exceeds the 

corresponding attainment-year inventory by more than 10.0 percent; and 

• the total maintenance area PM2.s emissions in the most recent NEI exceeds 

the corresponding attainment-year inventory by more than 30.0 percent. 

A Tier II trigger is activated when any violation of the annual PM2.5 NAAQS (15.0 ug/m3

) 

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 annual PM2.5 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 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 trigger activation or of the violation and any 

emissions control measures that may be necessary to prevent or correct, respectively, a 

violation of the NAAQS. Emissions reductions from 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 PM2.s and PM2.s 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. 
Ms. Carol Kemker 

September 23, 2013 

Page Three 

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, 

Keith Bentley, Chief " 

Air Protection Branch 

KB:JK:klc 

c: Lynorae Benjamin, EPA Region 4 

Jimmy Johnston, Air Protection branch