EPA Finalizes Changes to MATS Startup and Shutdown Rules

The Environmental Protection Agency (EPA) on Wednesday finalized changes to the Mercury and Air Toxics Standards (MATS), applying to periods of startup and shutdown at new and existing coal- and oil-fired power plants nationwide. 

As published in the Federal Register on Nov. 19, the final action on the EPA’s reconsideration of the startup and shutdown provisions for national emission standards for hazardous air pollutants revises work practice standards that must be used during those periods.

According to Stephanie Sebor, an attorney with law firm Winston and Strawn LLP, the changes specifically establish an alternative definition of “startup” under which startup would end four hours after a unit begins generating electricity.

“Under the previously finalized definition, startup would end at 1 MW,” she explains. “Use of this alternative startup definition is contingent upon the following requirements: (1) use of clean fuels to the maximum extent possible; (2) engagement of the [particulate matter (PM)] control device within one hour of adding coal; and (3) providing EPA with additional information in the Notification of Compliance Status such as [electric generating unit] and PM control device design characteristics, PM control device efficiency, and historic changes to the unit and the control device.”

The revised final rule also sets down alternative procedures for the use of sorbent trap monitoring systems during startup, says Sebor. “In addition, EPA clarified the application of the startup and shutdown work practice standards to units venting through a common stack and established default diluent caps and default electrical loads for calculating emissions during startup and shutdown.”

The final rule stems from 20 petitions for reconsideration of the February 2012–finalized MATS rule. The rule originally required sources to comply with numeric standards at all times and did not propose a work practice standard for startup and shutdown periods.

Petitioners raised concerns associated with measurement issues related to mercury and the data set to which the variability calculation was applied when establishing the new source standards for PM and hydrochloric acid. Petitioners also complained that the agency did not base the sulfur dioxide standard on a regulated utility unit and had finalized startup and shutdown provisions before the public had a chance to review and comment on them.

On Nov. 7, the EPA, meanwhile, issued a direct final rule and a “parallel proposed rule”to allow sources to submit MATS emissions data and reports in PDF form at least until the agency revises the emissions collection monitoring plan system. The rule is the first of in a suite designed to provide a single place for industry to submit their reports and data electronically.

Sonal Patel, associate editor (@POWERmagazine, @sonalcpatel)