§370.211. Design Flows

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.

 

a)         Design Average Flow

 

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.

 

b)         Design Maximum Flow

 

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.

 

c)         Design Peak Hourly Flow

 

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.

 

d)         Design Peak Flow

 

The design peak flow is the instantaneous maximum flowrate to be received.

 

(Source:  Added at 21 Ill. Reg. 12444, effective August 28, 1997)