The EPA's stance on Startup, Shutdown, or Malfunction (SSM) emissions has varied over the years. In 2013, EPA published a proposed rule about SSM in response to the 2011 Sierra Club petition that some State Implementation Plans (SIPs) violated provisions of the Clean Air Act (CAA), which require that emission sources continuously meet emission limitations. The proposed rule stated "planned" events of Startup/Shutdown are considered normal operations and therefore, exceedances of emission limits during these periods are violations of the CAA. A provision to keep Affirmative Defense for malfunctions in SIPs was included in this 2013 proposed rule. 36 states were included in the SIP Call. In September 2014, EPA further ratcheted down their proposal on SSM to eliminate all Affirmative Defense from SIPs for any CAA violation including malfunctions. With the 2014 Proposed SSM Rule update, Texas is now part of the SIP call where affirmative defense will no longer be acceptable for upsets/malfunctions. Per 70 FR 55920 dated September 17, 2014, Title 30 Texas Administrative Code (30 TAC) will need to be revised to remove Affirmative Defense noted in four (4) places for excess emissions that occur during upsets (30 TAC 101.222(b)), unplanned events (30 TAC 101.222(c)), upsets with respect to opacity limits (30 TAC 101.222(d), and unplanned events with respect to opacity limits (30 TAC 101.222(e)). Although these provisions were approved in 2010, the EPA is proposing to issue a SIP call for these affirmative SIP provisions since EPA now believes these provisions interfere with enforcement actions.
If approved as proposed, impacted states must revise their SIPs to allow special emission limits, control measures, or control techniques to minimize excess emissions. The expected submission deadline of the SIP revisions for impacted states is November 2016 with an effective date in 2017.