Whenever the governing body of any such city shall determine to construct or authorize the construction of any such improvements as provided in Kan. Stat. Ann. § 12-845 the governing body may proceed as provided by law to condemn the necessary lands or rights-of-way: Provided, Any person through or over whose lands any of such lines may be constructed or who would be otherwise damaged thereby may give consent thereto in writing, and such writing, with or without formal acknowledgment, may be recorded in the office of the register of deeds of the proper county, and such city shall have the same right to construct and maintain such lines as though such lands and rights had been formally condemned.