Section R. 560.419 - FloodplainsRule 419.
(1) The areas for initial and replacement on-site sewage disposal systems shall have natural ground surface elevation above the elevation defining the 100-year floodplain, where a floodplain exists.(2) The department shall ensure that the soil infiltrative surface of the sewage disposal system is located at an elevation that is above the elevation defining the 100-year floodplain.Mich. Admin. Code R. 560.419