(a) A preliminary plat shall be approved if the information provided indicates that the subdivision will be in conformance with applicable requirements of this Chapter.
(b) A final plat shall be approved if it is in conformance with applicable requirements of this Chapter. Provided, a final plat in substantial conformance with an approved and timely preliminary plat shall be presumed to be in conformance with applicable requirements of this Chapter. Provided further, such presumption shall not apply if there is a material and significant change in conditions since the preliminary plat was approved, or there is new or additional information which is material to the petition and which was not reasonably available at the time of the preliminary plat approval, and which is of such decisive nature that the preliminary plat would not have been approved had such conditions or evidence been known.