National Emission Standards for Hazardous Air Pollutants: Mercury Cell Chlor-Alkali Plants Residual Risk and Technology Review

Publication Date: 
Friday, January 8, 2021 - 4:00am

The U.S. Environmental Protection Agency (EPA) is proposing the results of the residual risk and technology review (RTR) of the National Emission Standards for Hazardous Air Pollutants (NESHAP) for mercury emissions from Mercury Cell Chlor-Alkali Plants, as required by the Clean Air Act (CAA). The EPA is proposing to find risks due to emissions of hazardous air pollutants (HAP) to be acceptable from the Mercury Cell Chlor-Alkali Plants source category, and to determine that the current NESHAP provides an ample margin of safety to protect public health and that no more stringent standards are necessary to prevent, taking into consideration costs, energy, safety, and other relevant factors, an adverse environmental effect. The EPA is proposing to amend the requirements for cell room fugitive mercury emissions to require work practice standards for the cell rooms and to require instrumental monitoring of cell room fugitive mercury emissions under the technology review. Furthermore, under our technology review and maximum achievable control technology (MACT) analysis, we are proposing to not require conversion to non-mercury production technology and invite comments and data and information regarding this proposed determination. In addition, the EPA is proposing standards for fugitive chlorine emissions from mercury cell chlor-alkali plants, which are not currently regulated under the NESHAP. The EPA is proposing to address applicability for thermal mercury recovery units when chlorine and caustic are no longer produced in mercury cells. The EPA is also proposing revisions related to emissions during periods of startup, shutdown, and malfunction (SSM); provisions for electronic submission of performance test results, performance evaluation reports, and Notification of Compliance Status (NOCS) reports; and correction of various compliance errors in the current rule.

Environmental Protection Agency