Where the subdivider can show that a provision of these general requirements and minimum standards of design would cause unnecessary hardship if strictly adhered to, and where, because of topographical or other conditions peculiar to the site, in the opinion of the planning commission, a departure may be made without destroying the intent of such provisions, the planning commission may authorize a variance. Any variance so authorized shall be entered in writing in the minutes of the planning commission. (Prior code § 12-4-6)