InfoSWMM Force Main Junction

[Darrell D]

Due to the nature of our GIS model, my model has a lot of junctions that are not manholes. How do I get these junctions to function as links in a force main so that effluent does not pond on them?

Specifically, I can't get my lift station to pump uphill. Once the flow in the pipe reaches the rim elevation of the previous junction (a valve), the flow stops. Although it's not shown, my guess is that the flow coming from the pump station is flowing out of the top of the up stream junction. I have unchecked the "Allow Ponding" selection. The image shows the highest level attained in SMAIN10637 which should flow to SREDUCER183.

[RossV]

Set the surcharge depth for that node to a level above your maximum elevation in the forcemain.

[Darrell D]

That did the trick! Thanks. Just getting started with InfoSWM.

[Robert Dickinson]

Hi Darrel,
In addition to Ross's comment here are some other rules for Force Mains

Subject: Pump / Force Main System in InfoSWMM




The basic system consists of:

1. Wet Well and its associated physical parameters,
2. Pump Type
3. Defined Pump Curve,
4. Downstream Pressure Node and
5. 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:

1. Volume - Flow
2. Depth – Flow
3. Head – Flow
4. Depth - Flow

Step 3: Define the Pump Curve in the Operation Tab

[Robert Dickinson]

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 ofInfoSWMM)




















Step 6: HGL Plot of the Force Main System








Step 7: Pump Summary in the RPT File