WSR 17-01-098

PERMANENT RULES

[Filed December 16, 2016, 4:19 p.m., effective February 1, 2017]

Effective Date of Rule: February 1, 2017.

Purpose: This technical amendment is being proposed to update the air dispersion screening model(s) the agency would allow to be used to show whether ambient concentrations of toxic air contaminants from new, modified or existing sources are acceptable. Regulation III, Section 2.07 specifies the process that the agency and sources will use when reviewing new, modified or existing sources both during the new source review permitting process and outside this permitting process. In order to show whether the impact from toxic air contaminants for the source will be acceptable, a computer model is used that predicts the ambient concentrations based on the predicted (or known) emissions from the source. The United States Environmental Protection Agency (EPA) develops the models for use by other agencies and sources. There are various types of models, including screening models and more in-depth models. The agency rule currently requires a screening model called TSCREEN to be used. This model is outdated, no longer supported by EPA, difficult to obtain, and does not function on modern day computers. The proposed rule revisions would eliminate the requirement to use TSCREEN and instead would allow any screening model recommended by EPA to be used. This would allow flexibility to accommodate new models when EPA adopts them as their recommended model(s).

Citation of Existing Rules Affected by this Order: Amending Regulation III, Section 2.07.

Statutory Authority for Adoption: Chapter 70.94 RCW.

Adopted under notice filed as WSR 16-22-084 on November 2, 2016.

Number of Sections Adopted in Order to Comply with Federal Statute: New 0, Amended 0, Repealed 0; Federal Rules or Standards: New 0, Amended 0, Repealed 0; or Recently Enacted State Statutes: New 0, Amended 0, Repealed 0.

Number of Sections Adopted at Request of a Nongovernmental Entity: New 0, Amended 0, Repealed 0.

Number of Sections Adopted on the Agency's Own Initiative: New 0, Amended 0, Repealed 0.

Number of Sections Adopted in Order to Clarify, Streamline, or Reform Agency Procedures: New 0, Amended 0, Repealed 0.

Number of Sections Adopted Using Negotiated Rule Making: New 0, Amended 0, Repealed 0; Pilot Rule Making: New 0, Amended 0, Repealed 0; or Other Alternative Rule Making: New 0, Amended 0, Repealed 0.

Date Adopted: December 15, 2016.

Craig Kenworthy

Executive Director

(a) Applicability. This section describes the procedures that shall be used for quantifying emissions and analyzing impacts of toxic air contaminants in order to meet the requirements for new or modified toxic air contaminant sources (see Article 6 of Regulation I) and for existing toxic air contaminant sources (see Section 2.05 of this regulation). In addition, definitions and procedures contained in chapter 173-460 WAC and adopted by reference in Regulation I, Section 6.01(a) apply to this section.

(b) Quantifying Emissions of Toxic Air Contaminants.

(1) The owner or operator of a new or modified toxic air contaminant source subject to Article 6 of Regulation I shall quantify toxic air contaminant emissions that may be discharged to the atmosphere after applying the required control technology, and shall submit this information as part of a Notice of Construction and Application for Approval.

(2) The owner or operator of an existing toxic air contaminant source subject to Section 2.05 of this regulation shall, upon request by the Agency, quantify toxic air contaminant emissions emitted by the facility and submit that information within 30 days.

(3) When quantifying toxic air contaminant emissions, the owner or operator shall assume that each toxic air contaminant is introduced into the atmosphere in an unaltered form continuously, at the maximum concentration known to exist at the source unless there is reliable data to the contrary or there is a physical or legal restriction.

(c) Analyzing Impacts of Toxic Air Contaminants. The air quality impact analysis for toxic air contaminant sources shall be performed using one of the following procedures:

(1) First Tier Review.

(A) Emissions of each toxic air contaminant discharged to the atmosphere shall be shown to be below the corresponding SQER listed in WAC 173-460-150; or

(B) ((The)) An EPA ((guideline)) recommended screening dispersion model((, TSCREEN,)) shall be used to demonstrate that the predicted concentration of each contaminant is below the corresponding ASIL listed in WAC 173-460-150. Stack parameters shall be submitted with the notice of construction application, or, for existing sources, within 30 days after the Agency requests the information. The maximum 1-hour concentration calculated by the model shall be converted with a persistence factor of 0.4 to a 24-hour average concentration or 0.08 to an annual average concentration; or

(C) The owner or operator shall submit a more comprehensive evaluation including the use of other EPA guideline models and more accurate emission estimation techniques to demonstrate that the predicted concentration of each contaminant is below the corresponding ASIL listed in WAC 173-460-150 in all areas where the general public has access; or

(2) Second and Third Tier Reviews. If predicted ambient concentrations from the first tier review are not below the ASILs listed in WAC 173-460-150, the owner or operator shall submit a petition to the Department of Ecology requesting a second tier or third tier review, and must receive Ecology's recommendation of approval for either the second or third tier petition. Second tier petitions shall follow the procedures in WAC 173-460-090. Third tier petitions shall follow the procedures in WAC 173-460-100.