Wash. Rev. Code § 36.94.340
When a municipal corporation and a county have entered into a written agreement providing for the transfer to such county of all or part of the property of such municipal corporation, proceedings may be initiated in the superior court for that county by the filing of a petition to which there shall be attached copies of the agreement of the parties and of the resolutions of the governing body of the municipal corporation and the legislative authority of the county authorizing its execution. Such petition shall ask that the court approve and direct the proposed transfer of property, and any assumption of indebtedness agreed to in consideration thereof by the county, after finding such transfer and acquisition of property to be in the public interest and conducive to the public health, safety, welfare, or convenience. Such petition shall be signed by the members of the legislative authority of the county or chief administrative officer of the municipal corporation and the chair of the legislative authority of the county, respectively, upon authorization by the governing body of the municipal corporation and the legislative authority of the county.
Within thirty days after the filing of the petition of the parties with copies of their agreement and the resolutions authorizing its execution attached thereto, the court shall by order fix a date for a hearing on the petition not less than twenty nor more than ninety days after the entry of such order which also shall prescribe the form and manner of notice of such hearing to be given. After considering the petition and such evidence as may be presented at the hearing thereon, the court may determine by decree that the proposed transfer of property is in the public interest and conducive to the public health, safety, welfare, or convenience, approve the agreement of the parties and direct that such transfer be accomplished in accordance with that agreement at the time and in the manner prescribed by the court decree.
RCW 36.94.340