No building permit for the construction of any new dwelling units shall be issued in an attendance area of an impacted school for which a declaration of impaction is presently in effect unless there has been filed with the director of building inspections either a certificate of mitigation or a certificate of waiver of mitigation which relates to the proposed construction. The provisions of this section shall not apply to the renewal of a building permit validly issued prior to the effective date of the ordinance codified in this chapter provided such renewal is made not later than sixty (60) days follow-ing said effective date. (Prior code § 67.01.140)