Repairs and alterations. Ordinary repairs and alterations may be made to a nonconforming building or structure, provided that no structural alterations shall be made in or to such building or structure, except those required by law, or except to make the building or structure and use thereof conform to the regulations of the district in which it is located. Ordinary repairs and alterations shall be determined by the Building and Zoning Officer or designee and shall include, among other things, the replacement of storage tanks where the safety of operations of the installation requires such replacement.