FACT SHEET Proposed Amendments to Air Toxics Standards for Primary Magnesium Refining ACTION • On January 4, 2021, the U.S. Environmental Protection Agency (EPA) proposed amendments to the 2003 National Emission Standards for Hazardous Air Pollutants (NESHAP) for Primary Magnesium Refining. • The Primary Magnesium Refining source category comprises one major source facility, US Magnesium LLC, located in Utah. This facility produces magnesium from brine (saltwater) taken from the Great Salt Lake. • Following a residual risk and technology review conducted under the Clean Air Act (CAA), EPA is proposing to: o Add a work practice standard for malfunction events associated with the chlorine reduction burner control device; the current emission limits will apply at all other times. o Establish a maximum achievable control technology (MACT) emissions standard for chlorine emissions from the chlorine bypass stack, which is currently unregulated by the NESHAP. o Add continuous pH measurement requirements for all control devices used to meet the acid gas emission limits of the rule. • EPA is also proposing other minor amendments to the rule, including: o Revising regulatory provisions related to emissions during periods of startup, shutdown and malfunction (SSM). o Adding provisions for electronic reporting of certain notifications and reports. RESIDUAL RISK ASSESSMENT • The CAA requires EPA to assess the risk remaining after application of the final air toxics emissions standard. This is known as a residual risk assessment. • The primary air toxics emitted by this facility include chlorine gas, hydrochloric acid and dioxins/furans, mainly from the melt reactor. • Based on the results of the risk review, EPA is proposing that risks from emissions of air toxics from this source category are acceptable and that after removing the exemptions for SSM, the NESHAP will provide an ample margin of safety. • We do not anticipate any adverse environmental effects as a result of HAP emissions from this source category. ------- TECHNOLOGY REVIEW • The CAA requires EPA to assess, review and revise air toxics standards, as necessary, taking into account developments in practices, processes and control technologies. • EPA is proposing to find one development in technology and practices that will require continuous pH monitoring for all control devices used to meet the acid gas emission limits of this rule. There are no other identified developments in practices, processes or control technologies for this source category. • EPA is proposing to establish a standard for chlorine gas emissions from the chlorine by- pass stack, which was identified as an unregulated source in the original NESHAP. BACKGROUND • The CAA requires EPA to regulate toxic air pollutants, also known as air toxics, from categories of industrial facilities in two phases. • The first phase is "technology-based," where EPA develops standards for controlling the emissions of air toxics from sources in an industry group or "source category." These MACT standards are based on emissions levels that are already being achieved by the best- controlled and lower-emitting sources in an industry. • Within eight years of setting the MACT standards, the CAA directs EPA to assess the remaining health risks from each source category to determine whether the MACT standards protect public health with an ample margin of safety and protect against adverse environmental effects. This second phase is a "risk-based" approach called residual risk. Here, EPA must determine whether more health-protective standards are necessary. • Also, every eight years after setting MACT standards, the CAA requires EPA to review and revise the standards, if necessary, to account for improvements in air pollution controls and prevention practices and technologies. HOW TO COMMENT • EPA will accept comments for 45 days after the proposal is published in the Federal Register. • Comments, identified by Docket ID No. EPA-HQ-OAR-2020-0535 may be submitted by one of the following methods: o Go to https://www.regulations.gov/ and follow the online instructions for submitting comments. o Send comments by email to a-and-r-docket@epa.gov. Attention Docket ID No. EPA- HQ-OAR-2020-0535. • Out of an abundance of caution for members of the public and our staff, the EPA Docket Center and Reading Room are closed to the public, with limited exceptions, to reduce the risk of transmitting COVID-19. Our Docket Center staff will continue to provide remote customer service via email, phone and webform. ------- o We encourage the public to submit comments via https://www.regulations.gov/ or email, as there may be a delay in processing mail and faxes. Hand deliveries and couriers may be received by scheduled appointment only, o For further information on EPA Docket Center services and their current status, please visit us online at https://www.epa.gov/dockets. FOR MORE INFORMATION • Interested parties can download a copy of the proposed rule notice from EPA's website at the following address: https://www.epa.gov/stationarv-sources-air-pollution/primary- magnesium-refining-national-emissions-standards-hazardous. • Today's action and other background information are also available electronically at https://www.regulations.gov/. EPA's electronic public docket and comment system. • For further technical information about the rule, contact Michael Moeller, EPA's Office of Air Quality Planning and Standards, at (919) 541-2766 or moeller.michael@epa.gov. ------- |