Not enough flow for a depressed siphon

[SMIAH]

Correct me if I'm wrong here.

I have to check the possibility to use a depressed siphon to get to a Sewage treatment plan. The inflow is 2 x 8 inches pipe and combined they give a PDWF of 0.5 cfs.

The Siphon should be a 8 inches pipe (or...force to a 6 inches).
Under the PDWF, the velocity is only 1.3 cfs (well under 3 cfs).

Plus, the PDWF is associated to a future development...

Need more flow?

 

[SMIAH]

Unanswered question - might be a tricky one then (didn't think it would be).

Peak Daily Wet Flow is 1/2 cfs.
Not enough flow rate to ensure a 3 cfs in the siphon.
I'd need a 5 inches pipe for so.