Any variance from the terms of Chapter
160, Zoning, or Chapter
161, Zoning Modifications and Additional Requirements, granted by the Board of Adjustment permitting the erection or alteration of any structure or structures or a specified use of any premises shall expire unless such construction, alteration or use shall have been actually commenced on or in each and every structure permitted by said variance within one year from the date of authorization by the Board of Adjustment and is diligently pursued to completion; except, however, that the running of this period shall be tolled from the date of filing an appeal from the decision of the Board of Adjustment to a court of competent jurisdiction, until the termination in any manner of such appeal or proceeding; provided, however, that if any variance is granted as part of a site plan or subdivision approval, the expiration of the variance shall occur upon the expiration of the site plan or subdivision approval.