Any person who continues any violation beyond the time limit provided for in Section 13.28.020 shall in addition to the items of expense provided in Section 13.28.010, become liable to the city for a penalty in the amount of ten percent of such expense items, together with interest thereon at eight and one-half percent per year from the date of the time limit provided in Section 13.28.020. (Ord. 947-04 § 2).