Nothing contained herein shall require any change in the plans or construction of any building or structure for which a permit was granted prior to the effective date of this chapter.  However, such construction must commence within thirty (30) days after this chapter becomes effective and be completed within a period of one (1) year after construction is initiated.  If construction is discontinued for a period of six (6) months or more, further construction shall be in conformity with the provisions of this chapter for the district in which the operation is located.