Ill. Admin. Code tit. 35 § 370.211
The following flows shall be identified in the basis of design for sewers, lift stations, sewage treatment plants, treatment units and other wastewater handling facilities.
The design average flow is the average of the daily volumes to be received for a continuous 12-month period of the design year, expressed as a volume per unit of time.
The design maximum flow is the largest volume of flow to be received during a continuous 24-hour period, expressed as a volume per unit of time.
The design peak hourly flow is the largest volume of flow to be received during a one hour period, expressed as a volume per unit of time.
The design peak flow is the instantaneous maximum flowrate to be received.
Ill. Admin. Code tit. 35, § 370.211
Added at 21 Ill. Reg. 12444, effective August 28, 1997