Commencement. When a permit has been issued, the permittee shall commence work within sixty (60) days from the date of issuance of the permit, except for good cause shown. Thereafter, the permittee shall have a duty to diligently perform the work to the conclusion of all work covered by the permit. Expiration. Road Construction Permits. Where the estimated cost of work is not more than Five Hundred Thousand Dollars ($500,000.00), the permit shall expire not more than two (2) years from date of issuance of permit. Where the estimated cost of permitted work is equal to, or more than, Five Hundred Thousand Dollars ($500,000.00), the permit shall expire not more than three (3) years from date of issuance of permit. The estimated cost of work for this determination shall include twenty-five percent (25%) for contingencies. Other Types of Permits. Permits for other than road and storm drainage construction, such as utilities, small wireless facilities, driveways, leadwalks, planting, sodding or seeding, minor grading, or haul roads, shall be valid for a period of time consistent with the scope of work, but in no case, less than six (6) months. No work will be allowed on an expired permit.