33.1-19-01-09. Wastewater treatment facility classifications.

Wastewater treatment facilities must be classified in one of five classes. Classifications must be based on population served, design population, type of treatment, character and volume of wastes to be treated, and the use and nature of the water resources receiving the facility effluent. Facilities may be classified at the discretion of the department if the facility has special design features or complex features or characteristics unusually difficult to operate, by reason of a waste unusually difficult to treat, conditions of flow, or the receiving water quality classification requiring an unusually high degree of facility operational control, or a combination of such conditions or circumstances.

1. Class IA. All wastewater stabilization ponds, land treatment facilities, wetlands treatment facilities, or other nonmechanical facilities requiring a minor degree of operational control serving a population equivalent of less than five hundred persons.

2. Class I. All wastewater stabilization ponds, land treatment facilities, wetlands treatment facilities, or other nonmechanical facilities requiring a minor degree of operational control serving a population equivalent of five hundred to less than ten thousand persons.

3. Class II. a. All mechanical facilities, mechanically aerated stabilization ponds, oxidation ditches, or other facilities requiring a moderate degree of operational control serving a population equivalent of less than ten thousand persons. b. All wastewater stabilization ponds, land treatment facilities, wetlands treatment facilities, or other nonmechanical facilities requiring a minor degree of operational control serving a population equivalent of ten thousand persons or more.

4. Class III. a. All mechanical facilities, mechanically aerated stabilization ponds, oxidation ditches, or other facilities requiring a moderate degree of operational and laboratory control serving a population equivalent of ten thousand persons or more. b. All activated sludge facilities, trickling filter facilities, rotating biological contactor facilities, separate sludge stabilization facilities, or other mechanical facilities requiring a high degree of operational and laboratory control serving a population equivalent of less than ten thousand persons.

5. Class IV. All activated sludge facilities, trickling filter facilities, rotating biological contactor facilities, separate sludge stabilization facilities, or other mechanical facilities requiring a high degree of operational and laboratory control serving a population equivalent of ten thousand persons or more.

History: Effective January 1, 2019; amended effective April 1, 2026.

General Authority: NDCC 23.1-07-06

Law Implemented: NDCC 23.1-07-03, 23.1-07-06