Modeling Off-Line Water Quality Unit

[Super Dave]

I am trying to model the operation of a control structure that splits flow to an off-line water quality unit(see figure). I first modeled the water quality storm using the system of 18" pipes that feed water to the WQU and then returns it to the control structure for discharge and it behaves well, identifying a discharge of 13.58 SCFS and everything is good, to me this is proof cf concept that the water quality storm is conveyed through the pipes. I include the model with the proposed 36" discharge pipe showing that the same 13.58 CFS discharge is modeled and that a splitter weir set at this elevation would then route flow through the WQU and everybody happy.

I tried to model the splitter weir that I show in the drawing as a Device 5 and require the sub-weirs through it, but the model assumes that all flow must go OVER the splitter weir and not through the 18" pipes, which is not the reality.

How do others model this sort of system? Any help appreciated. Thanks. David Campbell

 

[psmart]

Please see

http://www.hydrocad.net/chambers/offline.htm

Peter Smart
HydroCAD Software

http://www.hydrocad.net

 

[psmart]

If you're just trying to split the flow, you only need two outlet devices:

Device#1=18" culvert, routing=Primary (going to the WQU)

Device#2=Custom Weir/Orifice, routing=Secondary (going to the outlet pipe)

This will allow independent discharge through the culvert and over the weir.


Peter Smart
HydroCAD Software

http://www.hydrocad.net