Wash. Rev. Code § 35.69.030
Whenever the city council of any such city has adopted such resolution it shall cause a notice to be served on the owner of the property directly abutting on such portion of such street, instructing him or her to construct or reconstruct a sidewalk on such portion in accordance with the plans and specifications which shall be attached to such notice. The notice shall be deemed sufficiently served if delivered in person to the owner or if left at the home of such owner with a person of suitable age and discretion then resident therein, or with an agent of such owner, authorized to collect rentals on such property, or, if the owner is a nonresident of the state of Washington, by mailing a copy to his or her last known address, or if he or she is unknown or if his or her address is unknown, then by posting a copy in a conspicuous place at such portion of the street where the improvement is to be made. The notice shall specify a reasonable time within which such construction or reconstruction shall be made, and shall state that in case the owner fails to make the same within such time, the city will proceed to make it through the officer or department thereof charged with the inspection of sidewalks and that such officer or department will report to the city council, at a subsequent date, to be definitely stated in the notice, an assessment roll showing the lot or parcel of land directly abutting on such portion of the street so improved, the cost of the improvement, and the name of the owner, if known, and that the city council at the time stated in the notice or at the time or times to which the same may be adjourned, will hear any and all protests against the proposed assessment. Upon the expiration of the time fixed within which the owner is required to construct or reconstruct such sidewalk, if the owner has failed to perform such work, the city may proceed to perform it, and the officer or department of the city performing the work shall, within the time fixed in the notice, report to the city council an assessment roll showing the lot or parcel of land directly abutting on that portion of the street so improved, the cost of the work, and the name of the owner, if known. The city council shall, at the time in such notice designated, or at an adjourned time or times, assess the cost of such improvement against said property and shall fix the time and manner for payment thereof, which said assessment shall become a lien upon said property and shall be collected in the manner as is provided by law for collection of local improvements assessments under this title.
RCW 35.69.030