Sewer force main modeled in waterGEMS

Hello Benjamin,

The following link will be useful in knowing how to set up a model with air valves at a high point: communities.bentley.com/.../2662.modeling-air-valves-at-high-points-in-watercad-or-watergems-tn.

There are couple of key points. First, you will want to make sure the air valve is at the high point. Second, make sure the setting for "Treat as Junction?" is set to False. If this is set as True, the air valve will be treated like a junction with no demand.

Another point is that you may not need 10 air valves. If one of these is at the high point, try setting "Treat as Junction?" to False only for that one, and treat the others as junctions. If you still see negative pressures, try changing the settings other other air valves near those locations.

If this doesn't help, we will need a copy of the model to look into this. There are two options for sharing your model on Communities, whichever you choose please be sure to zip your files first. The first option is to attach the zip file containing your model to your reply on the forum using the Advanced Reply Editor (you'll find the link below and to the right of the reply box). If your data is confidential please use the instructions in the link below to send it via Bentley Sharefile. Files uploaded to Sharefile can only be viewed by Bentley employees. Please be sure to reply on this thread with the name of the file after it has been uploaded.

communities.bentley.com/.../7079.be-communities-secure-file-upload

If you upload the model to Sharefile, please post here with the name of the file so we know it is available.

Regards,
Scott

File Name: 150527 PS6 Force Main

The pump definitions are the original pump curves. Pump 3/4 was measured at 2077gpm and 176ft head in 2006. Pump 1/2 was measured at 1400gmp and 76ft head in 1995.

Thanks

Hello Benjamin,

Only the .wtg file was included. In order to look at the model, I will also need the database file, which as a file extension of .wtg.sqlite. This will be located in the same folder as the .wtg file. Once I you send the file, I can take a look at your model. You can use the same instructions that were previously sent to provide the file.

Regards,
Scott

Hello Benjamin,

In the model provided, I see two nodes with a negative pressure (J-164 at -1.1 psi and J-163 at -0.48 psi). These are near the end of the system. If you place an air valve in place of J-164, no junction will see a negative pressure.

Please give that a try and see if that helps with the issue you are seeing.

Regards,
Scott

Hello Benjamin,

In the model provided, I see two nodes with a negative pressure (J-164 at -1.1 psi and J-163 at -0.48 psi). These are near the end of the system. If you place an air valve in place of J-164, no junction will see a negative pressure.

Please give that a try and see if that helps with the issue you are seeing.

Regards,
Scott