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The South Coast Air Quality Management District (SCAQMD) Rule 1146 aims to reduce NOx emissions from boilers, steam generators, and process heaters rated at a heat input capacity of 5 MMBTU/hr or greater. Rule 1146 was last amended in December 2018 as part of SCAQMD's larger effort to expand rule applicability to transition facilities formerly governed by the Regional Clean Air Incentives Market (RECLAIM) program to a command-and-control regulatory structure.

December 2018 rule amendments updated NOx emission limits and set a concentration limit of 5 ppm ammonia for new and modified air pollution control equipment containing ammonia emissions in the exhaust. Currently, SCAQMD Regulation XIII requires Best Available Control Technology (BACT) for new and modified air pollution controls if there in an increase in ammonia emissions of 1 pound per day or more. Regulation XIII defines BACT for such equipment as 5 ppm ammonia, which parallels the current Rule 1146 ammonia limit.

Following evaluation of Regulation XIII and Rule 1146, SCAQMD has decided to remove the 5 ppm ammonia limit from Rule 1146 and allow the ammonia limit to be addressed exclusively through New Source Review. This will allow permit engineers to evaluate the ammonia limit on a case-by-case basis to ensure the NOx limits defined in Rule 1146 will be achieved. Key takeaway from the amended rule is that facilities subject to Rule 1146 will have greater flexibility with air pollution control technology to ensure NOx emission limits are achieved.

Although the amended rule will remove the ammonia concentration limit, Rule 1146 retains compliance demonstration obligations for new, replaced, and modified air pollution control equipment with ammonia emission limits as specified in a facility's SCAQMD permit. This compliance demonstration will include (1) quarterly source tests for the first year of operation and annual source tests after or (2) utilizing an ammonia continuous emissions monitoring system (CEMS).

SCAQMD is accepting comments until October 23, 2020 and has a public hearing to adopt the proposed amended rule set for December 4, 2020. The proposed amended Rule 1146 can be found here.

For questions specific to your facility, please email Colleen Grainger or call 949.567.9880.