The final plat original tracings shall be filed with the Village Planning Commission not later than twelve (12) months after the date of approval of the preliminary plat; otherwise, it will be considered void unless an extension is requested in writing by the subdivider and granted in writing by the Village Planning Commission. A copy of the final plat thus filed shall be transmitted to the Village Engineer. If found to be in full compliance with the formal provisions of these regulations, the Engineer will return said plat to the Commission, together with certification of approval.