Multiple-Family Adult Community Residential. Adult community as defined herein shall mean a residential community in which at least 80% of the dwelling units are permanently occupied by at least one person 55 years of age or over and in which no children under the age of 18 are permitted to reside on a permanent basis. Appropriate restrictive covenants shall be imposed upon the community to ensure compliance with these age restrictions and with the housing for older persons exemption of the Federal Fair Housing Act, 42 U.S.C. § 3601 et seq.