On December 19, 2008, the U.S. Court of Appeals for the District of Columbia Circuit decided a case that could affect any facility subject to a MACT standard, should the decision withstand anticipated appeals. The D.C. Circuit Court heard a case brought by Sierra Club against the U.S. EPA in which Sierra Club challenged the exemptions to numerical emissions limitations allowed under MACT standards (found in 40 CFR Part 63) for startup, shutdown, and malfunction (SSM) events.
Prior to the Court's decision, SSM events were exempt from the numerical emission limitations provided in MACT standards. Instead of complying with numerical emission limitations during SSM events, affected facilities are required to comply with the "general duty" to operate and maintain any affected facility in a manner consistent with safety and good air pollution control practices for minimizing emissions. In addition, affected facilities are required to develop a written Startup, Shutdown, and Malfunction Plan (SSMP) for the referencing MACT standard to assist in complying with the so-called "general duty" to minimize emissions during SSM events. However, the Court held that the SSM exemption and use of SSMPs does not meet the requirement that a Clean Air Act Section 112 standard apply continuously, and therefore vacated the SSM exemption.
As a result of this decision, EPA has the right to take enforcement action against any facility subject to a MACT standard each time an SSM event results in an exceedance of existing MACT limitations. Additionally, MACT-affected facilities may need to reexamine their MACT and Title V reporting procedures to ensure that SSM events are correctly categorized as MACT limit violations when appropriate. All instances should be examined on a case-by-case basis to determine the appropriate course of action.
The D.C. Circuit's invalidation of the SSM exemption rule will take effect in 45 days unless the court's mandate is automatically stayed by timely petitions for rehearing, or an order staying the mandate pending Supreme Court review. Once the rule is vacated, owners and operators of major sources under section 112 may have to comply with section 112 Maximum Available Control Technology (MACT) requirements during all stages of operation, including SSM events.
 40 CFR §63.6(e)(1)(i).