Treatment System

Permitted Daily Average Flow

Category

No Discharge Treatment Systems

All flows with a disposal system other than a subsurface area drip dispersal system

All flows with subsurface area drip dispersal systems

D
 
 

C

Pond Systems Preceded by Imhoff Tanks, Primary Clarifiers, or Facultative Lagoons

1.0 million gallons per day (MGD) or less

Greater than 1.0 MGD

D
 

C

Activated Sludge (Extended Aeration Mode) and Oxidation Ditch Systems

0.10 MGD or less

Greater than 0.10 MGD to 1.0 MGD

Greater than 1.0 MGD to 10.0 MGD

Greater than 10.0 MGD

D

C

B

A

Activated Sludge (Modes other than Extended Aeration)

0.050 MGD or less

Greater than 0.050 MGD to 1.0 MGD

Greater than 1.0 MGD to 10.0 MGD

Greater than 10.0 MGD

D

C

B

A

Trickling Filter, Rotating Biological Contactor, or other Fixed Film Processes

0.50 MGD or less

Greater than 0.50 MGD to 2.0 MGD

Greater than 2.0 MGD to 10.0 MGD

Greater than 10.0 MGD

D

C

B

A