Detroit-Ann Arbor, Michigan Area

DETROIT/ANN ARBOR, MICHIGAN

Effective Redesignation Date: 4/6/95 (60 FR 12459, 3/7/95)

Maintenance Plan - Key Features

• 1990 base year, 1993 attainment base, emissions budget through 2005
• continue to monitor ozone levels throughout the area
• conduct periodic inventories for the redesignated area every 3 years beginning in 1996; the inventories will consist of reviewing the assumptions of the maintenance demonstration; if substantial changes are discovered, the State will reproject the emissions for the maintenance period

Contingency Plan Trigger

• monitored air quality violation of the ozone NAAQS

Contingency Measures

• basic I/M
• NO_x RACT
• Stage I expansion
• Stage II (only in Wayne, Oakland, Macomb, and Washtenaw Counties)
• RVP reduction to 7.8 psi
• intensified RACT for degreasing operations

Schedule

• action begins after the trigger date (the date that the State certifies to EPA that the air quality data are quality assured and no later than 30 days after an ambient air quality violation is monitored)
• selection of appropriate contingency measure(s) based upon technical analysis using UAM
• 7.8 psi RVP reduction and intensified RACT for degreasing will commence 12 months after deciding on these measures
• basic I/M implementation within 1 year from the decision to use this measure
• NO_x RACT rules submitted 2 years from the decision to use this measure
• Stage I and Stage II implementation according to the schedule contained in Michigan's Stage I legislation (Senate Bill 726, section 9i)

For further information:

Jacqueline Nwia

Regulation Development Section (AR-18J)
Air Toxics Radiation Branch, Air and Radiation Division
U.S. EPA, Region V
77 West Jackson Boulevard
Chicago, Illinois 60604

Telephone: (312) 886-6081; Email: nwia.jacqueline@epamail.epa.gov

A violation has occurred in: Detroit, Michigan

Violation occurred on 7/31/95.

Actions - Information as of 10/18/95

• The State acknowledged violation (quality assured) within 30 days of the violation.
• The State is performing analyses to determine the most cost effective and best measure for emissions reduction. The State's recommendation will be made to the Governor.
• The Governor of Michigan must make decision on control measure by February 1996.
• Once selected, an adequate amount of time will be allowed for the contingency measure to work toward bringing the area back into attainment.

Actions - Information as of 9/20/96

• The State has implemented RVP of 7.8 as of July 1996 to continue through September 1996.