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May 8, 2000

Janet McCabe, Assistant Commissioner
Office of Air Management  
Indiana Department of Environmental Management
100 North Senate Avenue
Indianapolis, Indiana 46206

Dear Ms. McCabe:

Pursuant to Section 93.118(e)(4) of the Transportation Conformity Rule (40 CFR Part 93, Subpart A), the United States Environmental Protection Agency (USEPA) has reviewed the Lake and Porter Counties, Indiana ozone attainment demonstration submitted on April 30, 1998 and the supplemental information submitted on December 30, 1999 and February 21, 2000.  

The conformity rule identifies limited technical and administrative criteria that we must use in determining adequacy of submitted State Implementation Plan (SIP) budgets for transportation conformity purposes.  We have determined that the Lake and Porter Counties, Indiana ozone attainment demonstration contains adequate mobile source emission budgets for volatile organic compounds (VOC) and oxides of nitrogen (NOx) for the 2007 attainment year.

This adequacy finding means that the submitted 2007 motor vehicle emissions budgets for VOC and NOx for Lake and Porter Counties meet the standard requirements that any budget must meet before it can be used to determine conformity for a transportation improvement program or long range plan.  This adequacy finding does not relate to the merits of the SIP submittal nor does it indicate whether the submittal meets the USEPA’s requirements for approval of an attainment demonstration.

The USEPA opened a comment period on the SIP’s adequacy by posting it to our web site on January 7, 2000.  The web address is GOTOBUTTON BM_1_  The comment period closed on February 7, 2000, and no comments were received. The Indiana Department of Environmental Management’s comment period on the submittal closed February 10, 2000 and you did not receive any comments either.

The USEPA acknowledges that the Lake and Porter Counties, Indiana ozone attainment demonstration is undergoing refined urban air shed modeling and will be updated with the new modeling information.  In a April 28, 1998 letter to the USEPA, Indiana committed to submit the new modeling and any necessary updated control strategy information by December 2000.  

In summary, the USEPA finds that the 2007 motor vehicle emissions budgets for VOC and NOx submitted for the Lake and Porter Counties, Indiana ozone attainment demonstration have met the limited technical and administrative requirements of the transportation conformity adequacy criteria.  The USEPA also acknowledges that further modeling and refinement of the attainment demonstration is necessary.  Indiana has committed to submit these materials by December 2000.  In the December submittal, Indiana may refine the transportation conformity budgets in the attainment demonstration to be consistent with the new submittal.  If Indiana submits new transportation conformity budgets based on the updated modeling and attainment information, the submitted budgets will be subject to posting on the website, public comment, and review of adequacy.

More information on SIPs and adequacy reviews is also available on the USEPA web site.  The USEPA will soon publish a notice in the Federal Register announcing this adequacy finding.  If you have questions, please feel free to call me or Ryan Bahr, of my staff, at (312) 353-4366.

Sincerely yours,


Bharat Mathur, Director
Air and Radiation Division

cc: James E. Ranfranz, Executive Director
Northwestern Indiana Regional Planning Commission

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This Information Last Modified On: 09/18/2008 04:03 PM