Air Plan Approval; Iowa; Air Quality Implementation Plan-Muscatine Sulfur Dioxide Nonattainment Area and Start-Up, Shutdown, Malfunction SIP Call Withdrawal

The Environmental Protection Agency's (EPA) Region 7 Office is publishing a second supplemental notice of proposed rulemaking (SNPRM) to propose approval of Iowa's State Implementation Plan (SIP) for the 2010 1-hour Sulfur Dioxide (SO<INF>2</INF>) National Ambient Air Quality Standard (NAAQS) for the Muscatine nonattainment area, including the attainment plan control strategy. In this action, Region 7 is including additional technical information in the docket. Region 7 is also considering adoption of an alternative policy regarding startup, shutdown, and malfunction (SSM) exemption provisions in the Iowa SIP that departs from the policy detailed in EPA's 2015 SSM SIP Action, as well as proposing to withdraw the SIP call issued to Iowa as part of the 2015 SSM SIP Action and to approve the attainment plan control strategy.