Subject of Possible Rule Making: The department of ecology (ecology) is beginning rule making to amend chapter 173-400 WAC, Emission standards for combustion and incineration units; chapter 173-425 WAC, Outdoor burning; and chapter 173-430 WAC, Agricultural burning. Ecology intends to add the definition of "flame cap kilns" and modify the definition of "silvicultural burning" to include combustion. Ecology will also address the use of another type of outdoor burning device, air curtain incinerators, and how to obtain a permit for their use from ecology. This rule making may also consider other amendments to these chapters to clarify language and improve regulatory requirements for air quality.

Reasons Why Rules on this Subject may be Needed and What They Might Accomplish: The definitions of "flame cap kiln" and "silvicultural burning" are being added and modified, respectively, to align rule language with amendments made to RCW by SSB 6121, signed into law in the 2024 legislative session. Air curtain incinerators are increasingly being looked at as an alternative to open burning. It may be less emission intensive to use such units, and we will explore streamlining the ability to permit them.

Other Federal and State Agencies that Regulate this Subject and the Process Coordinating the Rule with These Agencies: The Washington department of natural resources is the lead agency for issuing silvicultural burn permits.

Local clean air agencies administer both the state and federal Clean Air Act programs in counties which have elected to activate a local air authority or to form a multicounty air authority.

Process for Developing New Rule: Ecology will follow the standard process for the adoption of rules under the Administrative Procedure Act (chapter 34.05 RCW).

Interested parties can participate in the decision to adopt the new rule and formulation of the proposed rule before publication by contacting Caitlyn Roehmholdt, Department of Ecology, Air Quality Program, P.O. Box 47600, Olympia, WA 98504-7600, phone 360-742-7554, Washington relay service or TTY call 711 or 877-833-6341, email caitlyn.roehmholdt@ecy.wa.gov, website https://ecology.wa.gov/WAC-173-425-430-400.

Additional comments: Interested parties can stay informed about the rule making and public involvement opportunities as described above. Ecology will extend an offer for government-to-government consultation with tribal governments during each phase of rule development.