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Comment Period

Chapter 173-340 WAC, Model Toxics Control Act Cleanup Regulations

Proposed rulemaking

Feb. 15, 2023 - April 16, 2023, 11:59 p.m.

You are invited to comment on Chapter 173-340 WAC, the Model Toxics Control Act (MTCA) Cleanup Rule. The Rule directs the investigation and cleanup of contaminated sites in Washington state.

The purpose of this rulemaking is to:

  • Improve the site hazard assessment and ranking process.
  • Revitalize MTCA cleanup program planning and assessment.
  • Update and clarify remedial investigation and remedy selection requirements.
  • Distinguish more clearly requirements applying to independent remedial actions.
  • Improve response to underground storage tank (UST) releases, and maintain federal approval of the state’s UST program, as required by Chapter 70A.355 RCW.
  • Strengthen environmental justice principles when prioritizing and cleaning up sites.
  • Advance public participation and tribal engagement.
  • Make the rule easier to use and understand.

Documents for review


We write rules to implement and enforce state and federal environmental laws and rules. We follow a three-phase process for rulemaking:

  1. Announcement and development
  2. Proposal
  3. Adoption

For each phase of the process, we update the rulemaking webpage and notify interested parties. We also file notice in the Washington State Register. To learn more about our rulemaking process, read the Frequently Asked Questions.

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Comment by mail

Sarah Wollwage
Department of Ecology
P.O. Box 47600
Olympia, WA 98504-7600
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Clint Stanovsky
Cleanup Rulemaking Lead

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