R 299.2911 Initial treatment facility and collection system classification.

Rule 11. (1) Except as provided for in subrules (3), (4), and (5) 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. Collection systems shall be classified by the department into 4 classes, designated as class C1, C2, C3, or C4, with class C1 being the highest. The classifications must be based on population served, the type of treatment facility or collection system, 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 and collection systems classified according to the population criteria in subrules (2) and (6) of this rule may be placed in a higher classification by the department, by reason of the incorporation in the treatment facility or collection system of special features of design, by characteristics more difficult to operate than usual, by reasons of a particularly difficult type of sewage, by reason of particular stream conditions or combinations thereof. (2) One of the following minimum classifications must 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 1 of the 2 following classes, designated as class L2 and L1: (a) Class L2, treatment facilities utilizing the waste stabilization lagoon process that include special mechanical devices such as aerators, chemical precipitation, disinfection, or other factors. Class L2 must be considered a higher classification than class L1. (b) Class L1, treatment facilities utilizing the waste stabilization lagoon process that 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. These treatment facilities include, but are not limited to, septic tank and tile field systems, and recirculating sand filters. (5) Class RTB, treatment facilities that retain and treat discharge from approved facilities serving a combined sewer system in accordance with its discharge permit. (6) Collection systems that convey wastewater to a treatment facility, with all flow transported through a combination of gravity sewers, gravity sewers and pump stations with force mains, or low-pressure collection systems, must be classified by the department into 1 of the 4 following classes, designated as class C1, C2, C3, or C4, with class C1 being the highest: (a) Class C1, collection systems serving or designed to serve a population of 50,000 or more persons. (b) Class C2, collection systems serving or designed to serve a population of 10,000 or more, but less than 50,000, persons. (c) Class C3, collection systems serving or designed to serve a population of 2,000 or more, but less than 10,000, persons. (d) Class C4, collection systems serving or designed to serve a population of 150 or more, but less than 2,000 persons unless otherwise required by the department.