HydroCAD multistage outlet 1

[amicka]

I am using HydroCAD to model a catch basin with two inlets and two outlets and am having trouble figuring out how to go about it. The two inlets are a rectangular orifice to control the flow of the 10-year storm and a top grate to allow the 25-,50-, and 100-year storms to enter the catch basin. The two outlets are an orifice flowing out into an infiltration trench from the bottom of the catch basin and an elliptical pipe flowing out of the catch basin.

The catch basin is on the downslope side of a detention basin. Do I need to create a new node for my catch basin, or can I add data to the detention basin node?

 

[psmart]

This sounds like a typical riser structure as discussed at

http://www.hydrocad.net/pond1.htm

But while a riser normally has just converging flows (the "inlets"), your outflow is also being split in two.

To handle this, you may need to use two ponds: Pond 1 will include the main pond storage, and will have two outlet devices (the orifice and top grate) both routed to primary.

Route the primary outflow to Pond 2, which will be used to model the riser outlets. You can probably use the Catch Basin option (for a zero-storage pond). Pond 2 will have an outflow pipe (routed to primary) and an orifice (routed to discarded.)

The only draw-back of this approach is that you may need to switch to a tailwater-sensitive routing procedure in order to handle the tailwater inside the riser. But don't jump the gun. The software will give you a warning if it detects a potential tailwater dependency.