A Site Plan shall become effective upon certification of approval by the City Council. The City Council approval of any Site Plan required by this article shall remain valid for one (1) year. A one (1) year extension may be granted with approval of City Council. If development has not been established or construction commenced within one (1) year or two (2) years in case of a received extension, then the Site Plan shall be deemed null and void. For the purpose of this article “actual construction” shall mean that the permanent placement of construction materials and utility work has started and is proceeding without undue delay with an approved building permit. Preparation of plans, securing financial arrangements, issuance of building permits, letting of contracts, grading of property, or stockpiling of materials on the site shall not constitute actual construction. At the time of Site Plan approval, the City Council may grant an exemption on the time construction shall begin after their approval is given for a utility service structure.