Approval and Promulgation of Air Quality Implementation Plans; State of Colorado; Revised Denver PM10 Maintenance Plan

EPA is taking direct final action approving a State Implementation Plan (SIP) revision submitted by the State of Colorado. On September 25, 2006, the Governor's designee submitted a revised plan for particulate matter with an aerodynamic diameter, less than or equal to 10 microns (PM10) for the Denver metropolitan area for the PM10 National Ambient Air Quality Standard (NAAQS). This revised maintenance plan addresses maintenance of the PM10 standard for a second ten-year period beyond redesignation, extends the horizon years, and contains revised transportation conformity budgets. EPA is approving the removal of Regulation No. 11, "Motor Vehicle Emissions Inspection Program" from Denver's revised PM10 maintenance plan. In addition, EPA is approving a transportation budget trading protocol for estimating the PM10 and nitrogen oxides (NOx) for each conformity determination. This action is being taken under section 110 of the Clean Air Act.