Revision to the Idaho State Implementation Plan; Approval and Promulgation of Air Quality Implementation Plans: Idaho, Northern Ada County PM10 Second Ten-Year Maintenance Plan and Pinehurst PM10 Contingency Measures

The Environmental Protection Agency (EPA) is approving the Northern Ada County PM<INF>10</INF> Second Ten-Year Maintenance Plan submitted by the Idaho Department of Environmental Quality (IDEQ) on March 11, 2013, for particulate matter with an aerodynamic diameter less than or equal to ten micrometers (PM<INF>10</INF>). Northern Ada County was identified as an area of concern for PM<INF>10</INF> with the promulgation of the PM<INF>10</INF> NAAQS in 1987, and was formally designated as a moderate PM<INF>10</INF> nonattainment area upon passage of the 1990 Clean Air Act (CAA) amendments. In October 2003, the EPA approved the Northern Ada County PM<INF>10</INF> Maintenance Plan and redesignated the area to attainment for PM<INF>10</INF>. This revised Maintenance Plan addresses maintenance of the PM<INF>10</INF> standard for a second ten-year period beyond redesignation through 2023, extends the horizon years, and contains revised transportation conformity budgets. The EPA is also approving the February 15-16, 2011 high wind exceptional event at the Boise Fire Station monitor, as well as contingency measures for the Pinehurst PM<INF>10</INF> Air Quality Improvement Plan. The EPA is approving the second ten-year PM<INF>10</INF> Maintenance Plan for Northern Ada County and the Pinehurst PM<INF>10</INF> contingency measures pursuant to section 110 of the CAA. The EPA is approving the February 2011 exceptional event pursuant to 40 CFR 50.14. The EPA received one set of adverse comments focused primarily on proposed coal export terminals that may be built in Oregon and Washington that may affect Northern Ada County.