View Full Version : Error in Pump Discharge Flows

February 24, 2014, 08:23 PM
I've come across what seems to be an error in H2Omap SWMM where flows downstream of a pumping station are vastly different to the pumped flows. The pump operates for a short period of time at 20-30 L/s. In the downstream gravity main flows are less than 10 L/s. See attached graph.

Has anyone come across this problem before and know how to fix it?

Robert Dickinson
February 25, 2014, 04:00 AM
Hi Patrick,
A few suggestions:
1. You say gravity main but do you mean force main using Hazen Williams? A HW force main will react better to the pumped flows compared to the gravity main
2. Did you had a surcharge depth to the node downstream of the pump so the link downstream is under pressure and stays on the pump curve?
3. If you have a pump that turns on a lot of times you might need to use a smaller time step.
4. If you are getting reverse flow then a flap gate should help
5. If that does not work then send me your model to suppport@innovyze,com and I can comment
Bob Dickinson

PS Here are a few blogs about this matter



Pump / Force Main System in InfoSWMM and SWMM 5

Subject: Pump / Force Main System in InfoSWMM and SWMM 5
The basic system consists of:
· Wet Well and its associated physical parameters,
· Pump Type
· Defined Pump Curve,
· Downstream Pressure Node and
· Downstream Force Main
Figure 1: The Basic System

Step 1: Wet Well Data
Enter the invert elevation, maximum depth of the Wet Well, the physical shape as either a function or shape table and any evaporation or infiltration.

Step 2: Define the Pump Type
The pump type is defined by a Pump Curve and the On and Off elevations:
The four types of pumps are:
· Volume - Flow
· Depth – Flow
· Head – Flow
· Depth - Flow

Step 3: Define the Pump Curve in the Operation Tab

Step 4: Set a Surcharge or Pressure Depth at the Downstream end of the Pump
Any positive Surcharge Depth in the Node will allow the program during the simulation to keep the node under pressure forcing flow through the Force Main.

Step 5: Force Main Data
Define the downstream pipe(s) from the pump as Force Main conduits with either a Hazen Williams or Darcy-Weisbach coefficient (defined in the SWMM 5 options or the Run Manager of InfoSWMM)

Lucas Tipton
May 21, 2015, 03:23 PM
Was anyone able to help you with this? I am having a similar problem.

Robert Dickinson
May 21, 2015, 03:57 PM
Was anyone able to help you with this? I am having a similar problem.

Gladly, Lucas. Can you send me your ISDB folder (zipped) and MXD file to me at support@innovyze.com

Robert Dickinson

PS it looks like you sent it to my colleague so I will look at it now