567—81.3 (455B) Wastewater treatment plant grades.
	 81.3(1) Classifications. The wastewater treatment plant classifications are listed in the following table:
Wastewater Treatment Plant Classifications

Treatment Type	Grade	
	Based on Design Pounds of BOD5/day	
	less than 334	334-835	836-2,505	2,506-8,350	more than 8,350	
 	Based on Design Population Equivalent	
	less than 2,000	2,000-5,000	5,001-
15,000	15,001-
50,000	more than 50,000	
1. Primary Treatment	I	I	II	III	IV	
2. Waste Stabilization Lagoon	IL	IL	IL	IL	IL	
3. Aerated Lagoon System	IL	IL	IIL	IIL	IIL	
4. Fixed Film Biological Treatment	II	II	III	III	IV	
5. Activated Sludge	II	III	III	IV	IV	
	 81.3(2) Unknown design BOD  5  loading. When the design BOD 5  loading is unknown, the plant BOD 5  loading shall be determined by using the average pounds of BOD 5  of the 24-hour composite samples taken in the last 12 months. If no 24-hour composite samples were taken, then grab samples shall be used.
	 81.3(3) IL and IIL wastewater operator requirements. A Grade I, II, III, or IV wastewater treatment certificate will satisfy the certification requirements for a Grade IL plant. A Grade II, III, or IV wastewater treatment certificate will satisfy the certification requirements for a Grade IIL plant.