If the work is not commenced under any permit, or if the work is not satisfactorily prosecuted after its commencement, such permit will be considered as having expired and shall be null and void. This section is not to apply to permits secured prior to completion of the sewer system. These permits will be valid for the period of time allowed in the ordinances for original connections to the sewer. (Ord. 304, 3-6-1966)