simulating downslope force main using SewerCAD or SewerGEMS

Question

Hollo, 
 I am wondering if SewerCAD or SewerGEMS can model the following downslope force main. The force main is initially dry. 
 What I want to see are: 
 1) water profile at each moment, i.e., water depth at every point at every moment. 
 2) will the system be stable at each flow condition? I define "stable" as the water depth at every point in the pipe does not change with time. 
 3) if the system is stable, when it is stabilized at every flow condition? 
 I think pressure pipe is treated as a line in sewerCAD or sewerGEMS. So there is no way to describe water depth in a pressure pipe. Please tell me whether I am wrong. 
 I used conduit (gravity sewer) in SewerCAD to model force main and I can not understand some of the simulation results. 
 Thank you in advance.

Tom Walski · Accepted Answer

In order to solve this type of problem, you need to use either the explicit or implicit dynamic wave solvers in SewerGEMS. The GVF routing in SewerCAD is too approximate to determine the rate of filling of the downstream pipes. It will only tell you the new steady state condition. 
 
When you turn the pump on in the model, P1 and P2 will gradually fill. Whether pipes P1 and P2 will ever flow full depends on the pump flow rate, the pipe size, the downstream boundary condition and the slope of the pipes. If the pump stays on long enough, a new steady state will be reached, either full or partly full. 
 
If the pipe fills and point A is open to atmosphere, it will overflow. You will probably want an air release valve at the high point.