Washington Revised Code Title 7. Special Proceedings and Actions § 7.05.430. Termination of proceedings

(a) The claimant withdraws its claim, unless the respondent objects thereto and the arbitral tribunal recognizes a legitimate interest on the respondent's part in obtaining a final settlement of the dispute;

(b) The parties agree on the termination of the proceedings; or

(c) The arbitral tribunal finds that the continuation of the proceedings has for any other reason become unnecessary or impossible.