If, incidental to the construction or maintenance of a state public facility, the department determines and orders that an encroachment previously authorized by written permit must be changed, relocated, or removed, the owner of the encroachment shall change, relocate, or remove it within a reasonable time set by the department in the order. The cost of the change, relocation, or removal shall be paid as provided in AS 35.10.220(c). If the owner does not change, relocate, or remove an encroachment within the time set by the department, the encroachment is considered an unauthorized encroachment and subject to the provisions of AS 35.10.270.