Section R. 299.2911 - Initial treatment facility classificationRule 11.
(1) Except as provided for in subrules (3) and (4) of this rule, treatment facilities shall be classified by the department into 4 classes, designated as Class A, B, C, or D, with Class A being the highest. The classifications shall be based on population served, the type of treatment facility, the character and volume of wastes to be treated, and the use and nature of the waters of the state receiving the effluent thereof. Treatment facilities classified according to the population criteria in subrule (2) of this rule may be placed in a higher classification by the department, by reason of the incorporation in the treatment facility of special features of design, or characteristics more difficult to operate than usual, or by reasons of a particularly difficult type of sewage or by reason of particular stream conditions or combinations thereof.(2) One of the following minimum classifications shall be assigned to each treatment facility that serves the public:(a) Class A, treatment facilities serving or designed to serve a population of 50,000 or more persons.(b) Class B, treatment facilities serving or designed to serve a population of 10,000 or more, but less than 50,000, persons.(c) Class C, treatment facilities serving or designed to serve a population of 2,000 or more, but less than 10,000, persons.(d) Class D, treatment facilities serving or designed to serve a population of less than 2,000 persons.(3) Treatment facilities utilizing the waste stabilization lagoon process shall be classified by the department into one of the 2 following classes, designated as class L2 and L1: (a) Class L2, treatment facilities utilizing the waste stabilization lagoon process which include special mechanical devices such as aerators, chemical precipitation, disinfection, or other factors. Class L2 shall be considered a higher classification than class L1.(b) Class L1, treatment facilities utilizing the waste stabilization lagoon process which do not include special mechanical devices such as aerators, chemical precipitation, disinfection, or other factors.(4) Treatment facilities that require minimal operation and control, and serve a population of less than 1,000 persons may be classified by the department as a special classification, designated as class SC. Such treatment facilities include, but are not limited to, septic tank and tile field systems, and recirculating sand filters.Mich. Admin. Code R. 299.2911