### IDEM INDIANA DEPARTMENT OF ENVIRONMENTAL MANAGEMENT We ProtectHoosiers andOurEnvironment. MitchellE. DanielsJr. 100 North Senate Avenue Governor Indianapolis, Indiana 46204 (317) 232-8603 Thomas W. Easterly Toll Free (800) 451-6027 Commissioner www.idem.IN.gov

April 14. 2011 Ms. Susan Hedman Regional Administrator U.S. Environmental Protection Agency Region 5 77 West Jackson Boulevard Chicago, IL 60604-3950
Re: Requestto Parallel Process the Draft Request for Redesignation Petition and Maintenance Plan Underthe Annual National Ambient Air Quality Standard for Fine Particles forthe Central Indiana NonattainmentArea
Dear Ms. Hedman:
The Indiana Department of Environmental Management (IDEM) submits a draft Redesignation Petition and Maintenance Plan forthe Central Indiana Nonattainment Area, which was designated as nonattainment ofthe annual standard forfine particles on April 5, 2005. IDEM will conduct a public hearing concerning the Redesignation Petition and Maintenance Plan on May 17, 2011, and the public comment period will conclude on May 19, 2011. IDEM requests the United States Environmental Protection Agency (U.S. EPA) to proceed with its proposed approval of IDEM's October20, 2009 submittal and to parallel process this draft submission concurrently.
The attached document consists ofthe following: 

### Redesignation Petition andMaintenance Plan • A formal request thatthe Central Indiana Area be redesignated to attainment and reclassified as maintenance. Itcontains and meets the requirements setforth in Section 107 ofthe Clean AirAct and in U.S. EPA Redesignation Guidance.
• A maintenance year of2025 is established and 2015 and 2020 are analyzed as interim years.

• The appendices ofthe document contain historical airqualitytrend data, projected emission inventorydata and thorough documentation ofthe mobile emissions analysis.

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### ('i) An E<lual Opportunity Employer PleaseRecycleMs. Hedman, Page 2

Motor Vehicle Emissions Budget

• Contained in the Redesignation Petition is a new MotorVehicle Emissions Budgetfor 2015 and 2025. The Indianapolis Department of Metropolitan Development's travel demand forecasting model and the U.S. EPA's software program referred to as MOBILE6.2 were used to determine emissions forthe annual fine particle nonattainmentarea.
• A conservative margin of safetywas applied to the 2015 and 2025 projected emissions.

• The travel demand model was updated with the best available assumptions.

• Vehicle registration data gathered from the Indiana Bureau of MotorVehicles were used to replace the MOBILE6.2 defaultvehicle age distribution.
As noted above, IDEM will conduct a public hearing on May 17, 2011 and the public comment period will close on May 19, 2011. Upon completion ofthe public participation process and documentation, IDEM will forward the official transcript and a summary and response to substantive oral and written comments underseparate cover. "- 

## '- IDEM request that U.S. EPA proceed with review and approval ofthis submittal. Ifyou have any questions or need additional information, please contact Scott Deloney, Chief, Air Programs Branch, at (317) 233-5694. Sincerely,

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### -"I 12**~~ Uc~**  Keith Baugues Assistant Commissioner Office ofAir Quality

KB/sad/skr Enclosures: Draft Requestfor Redesignation Petition and Maintenance Plan Underthe Annual National Ambient Air Quality Standard for Fine Particles forthe Central Indiana NonattainmentArea

cc: John Mooney, U.S. EPA Region 5 (no enclosures) Matt Rau, U.S. EPA Region 5 

### (wienclosures) John Summerhays, U.S. EPA Region 5 

### (wienclosures) Cheryl Newlon, U.S. EPA Region 5 (no enclosures) Pat Morris, U.S. EPA Region 5 (no enclosures) Scott Deloney, IDEM (no enclosures) Christine Pedersen, IDEM (no enclosures) Sarah Raymond, IDEM 

### (wienclosures)