How to discard water quality volume to an arbitrary outfall?

Hi, 

I have a model in which a pond goes to an outlet structure to go directly to our storm system. However, we want to discard the water quality volume from that same pond to go to arbitrary outfall so it does not affect downstream of our system. I know what the volume that I need to discard is. 

Therefore, I was wondering if it would be as simple as having two outlet structures with pipe attached to each of them, one for the water quality volume and one for the rest of the flow? For the water quality volume the pipe after the outlet structure would end in an outfall. 

How would I make sure that only the amount of XXX of volume  is taken to that pipe? 

Thanks

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  • Paola,

    In general you will want to model the system as close as possible to the real system. What in the real system limits the outflow based on volume? (how is that accomplished?) 

    You can indeed model multiple outlets leaving the same pond. See the "Pond" section of this article: Modeling a flow split (diversion) in SewerGEMS or CivilStorm

    With the pond outlet structure component in SewerGEMS, you can control outflow based on the available outlet types: orifice, weir, riser, vortex valve, user defined rating table. If you want to assume a specific, constant outflow that yields a certain volume, you could use the user defined rating table pond outlet type, assign it to a second pond outlet node attached to the pond, then connect that to a free outfall via a conduit.

    Or, if this specific volume you're looking to "discard" is actually infiltration (water soaking into the ground around the pond), you can use one of the available seepage methods.


    Regards,

    Jesse Dringoli
    Technical Support Manager, OpenFlows
    Bentley Communities Site Administrator
    Bentley Systems, Inc.

Reply
  • Paola,

    In general you will want to model the system as close as possible to the real system. What in the real system limits the outflow based on volume? (how is that accomplished?) 

    You can indeed model multiple outlets leaving the same pond. See the "Pond" section of this article: Modeling a flow split (diversion) in SewerGEMS or CivilStorm

    With the pond outlet structure component in SewerGEMS, you can control outflow based on the available outlet types: orifice, weir, riser, vortex valve, user defined rating table. If you want to assume a specific, constant outflow that yields a certain volume, you could use the user defined rating table pond outlet type, assign it to a second pond outlet node attached to the pond, then connect that to a free outfall via a conduit.

    Or, if this specific volume you're looking to "discard" is actually infiltration (water soaking into the ground around the pond), you can use one of the available seepage methods.


    Regards,

    Jesse Dringoli
    Technical Support Manager, OpenFlows
    Bentley Communities Site Administrator
    Bentley Systems, Inc.

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