Env: Contact Tank

[GTScott]

I am making this up...easy one but you have to find one thing.

What volume, in cubic feet, is required for a chlorine contact tank if the plant flow is 2 MGD?

A ) 2800

B ) 3400

C ) 5500

D ) 10900

 

[GTScott]

No one? Come on, this is a 30 second problem.

 

[Road Guy]

B?

 

[RIP - VTEnviro]

Are we assuming 30 minutes of contact time, which is generally the standard?

 

[GTScott]

Standard detention time is 30 mins...this is in CERM somewhere if you don't already know this.

t=V/Q

V=tQ

t=30 mins = 1800 s

Q = 2 MGD = ~3.09 cfs

Volume = (1800s) x (3.09 cfs)

Volume = 5,562 cf

 

[DVINNY]

I guess "C"???????

 

[GTScott]

The only trick to this was knowing where to find the standard contact time requirement if you did not already have it.

 

[Road Guy]

rayers:

 

[RIP - VTEnviro]

The only trick to this was knowing where to find the standard contact time requirement if you did not already have it.

I learned it out of the 10-state standards when we did the WW system for a rest area.

I know that's a "local" standard and they don't specifically ask questions on local stuff. But, if it's good enough in your state, and you don't know otherwise, it's probably a reasonable number to start with.