Every variance from the provisions of this title granted by the Planning Commission, or where applicable on appeal thereof by the City Council, shall be granted only subject to such conditions as will assure that the adjustment thereby authorized will not constitute a grant of special privilege inconsistent with the limitations upon other properties in the vicinity and district in which the subject property is situated, and shall contain as a condition thereof the following:
"The variance hereby allowed is conditioned upon the privileges granted herein being utilized within 180 days after the effective date hereof, and should the privileges authorized hereby fail to be executed or utilized or where some form of construction work is involved, such construction has not actually commenced within such 180 days, and is not diligently prosecuted to completion, this authority shall become null and void and any privilege or variance granted hereby shall lapse unless such variance has not been utilized within such 180 day period by reason of delays caused by the Community Development Department in approving plans, in which event the Planning Commission may grant a reasonable extension of time. The Planning Commission may, in its discretion and with the consent or upon the request of the applicant, for any cause, grant a reasonable extension of time in addition to the 180 days herein provided. Such requests for extension shall have been filed with the Community Development Director 15 days prior to the expiration of the 180 day time limit noted above."