All parking spaces required by this Ordinance shall be provided on the same lot with the main building or use that it serves. Upon demonstration that the parking spaces required are not available and cannot reasonably be provided on the same lot as the building, structure or use it serves, the Planning Commission may permit the required parking spaces to be provided on any lot, of which a substantial portion is within 400 feet of such building, structure, or use. This provision shall require submittal of evidence of ownership or valid agreement to lease the parking area off-site that is intended to be used to comply with this article.