The permittee shall be obligated to commence work within twenty-four hours from the date of issuance of the permit, and the excavation shall be made and all necessary work shall be performed and completed within seven days after commencement. However, the Service Director may, in his or her discretion, grant a time extension which shall be endorsed on the back of the permit with the reason therefor. No time extension shall be valid unless it is dated and signed by the Director.
(1966 Code § 901.04)