RCW 35.44.310

The reassessment shall be for an amount which shall not exceed the actual cost and expense of the improvement, together with the accrued interest thereon, it being the true intent and meaning of the statutes relating to local improvements to make the cost and expense of local improvements payable by the property specially benefited thereby, notwithstanding the proceedings of the council, board of public works or other board, officer, or authority may be found to be irregular or defective, whether jurisdictional or otherwise.