SewerGems Model User Notifications

Question

I did a sewer model run and upon validating it, I received the following user notifications: 
 1. "This node type is invalid as the Suction-side node to a pump. A pump must be a storage element type such as a pond or wet well." 
 2. "A pump must be connected to a storage element, such as a Pond or Wet Well, using a single pipe." 
 3. "Pump discharge link is inactive, not selected or doe not exist." 
 The pump station includes a wet well, 2 pumps, which are connect by pressure pipes and leave the pump station, which is then connected to a node. I tired to include a picture, but it's not working for me. Any insights would be greatly appreciated. Thank you in advance.

Yashodhan Joshi · Answer

Hello Marie, 
 Marie Betty Lafortune said: "This node type is invalid as the Suction-side node to a pump. A pump must be a storage element type such as a pond or wet well." 
 For this user notification check the element downstream of a pump. What kind of element is selected downstream of the pump? As the user notification says, the downstream element should be a "storage" type element such as a wet-well or a pond. Ensure that such an element is present downstream of the pump/s. 
 Marie Betty Lafortune said: "A pump must be connected to a storage element, such as a Pond or Wet Well, using a single pipe." 
 This is similar to the above user notification but ensure that a single pipe is connected from your wet-well or pond to the pump. 
 Marie Betty Lafortune said: 3. "Pump discharge link is inactive, not selected or doe not exist." 
 
 Check if you have set "Downstream Link" properly for the pumps. The downstream link is the downstream pipe or discharge pipe for the pump. See the below article which explains how to set it up; 
 Error / User Notification: Error executing query. Pump Discharge link is inactive, not selected or does not exist. 
 
 Try to share a snapshot of your system so that we can understand if anything is not setup properly which is causing problems to run your model. To insert images or attach files, select Insert > Insert Image / Video File in the editor toolbar. 
 Let me know if this helps.

Yashodhan Joshi · Answer

Hello Marie, 
 The pumps are not oriented properly. The discharge end of the pumps is facing the wet-well. The pumps should be reversed in this case to discharge to the junction. See the below wiki article for reversing the orientation of pumps; 
 How do you change the direction of the downstream pipe for valves and pumps? 
 Another issue I see is that the junction connected to both the pumps seems to have two additional pipes which are not connected to anything else. Delete those elements if created accidently. See the snapshot below in which I have highlighted the issues; 
 
 Hope this helps.

Jesse Dringoli · Answer

You can click the manhole and press the delete key or right click on it and choose the Delete option. This will delete the adjacent conduits, though, as a conduit must always be connected to a node on either end. 
 If you are wanting to lay out bends instead of nodes, hold down the control key when laying out the conduit and when you click, it will lay out a bend (vertex) instead of a manhole. If you click (without the CTRL key pressed) on another existing element, it will connect the conduit to that element, or you can right click and change the element type to create when clicking. 
 If you want to include a node to model a change in slope or pipe type/diameter but do not want to use a manhole vertical vault structure, use the transition element instead. See: Pressure Junction vs Transition vs Manhole 
 If you are new to SewerGEMS, there are many good learning resources here: Learning Resource Guide for new users of Bentley SewerGEMS

Yashodhan Joshi · Answer

Hello Marie, 
 I think this relates to wet-well elevations. I am sharing an article which will help you understand the "tank" operating range. See the link below; 
 Understanding Tank Operating Range 
 Although the article above has definitions for "tanks" used in water supply systems; I am providing the corresponding definitions in case of "wet-wells" as below; 
 Elevation (Ground): Ground Elevation based on topography 
 Elevation (Invert): This must be related to a pressure pipe or conduit. A wet-well would have "Elevation (Minimum)" which corresponds to the lowest allowable water level in the wet-well. 
 Elevation (Initial): Starting water level of the wet-well 
 Elevation (Maximum): Maximum allowable water level in the wet-well. This generally corresponds to the top of the wet-well. 
 Since a wet-well is usually situated underground the elevations would be such; 
 Elevation (Ground) > Elevation (Maximum) > Elevation (Initial) > Elevation (Minimum) > Elevation (Base). 
 The Elevation (On) and (Off) pertain to pump "On" and "Off" elevations. These elevations control the pump start and stop routines. When the level of water in the wet-well reaches either of these the pump status would be changed. E.g. if the water level matches the "On" elevation, the pump would start pumping and similarly it would stop pumping when the wet-well level matches the "Off" elevation. See the below article for more clarity on this; 
 Pump On/Off Elevations vs. Logical Controls vs SWMM Control sets 
 Let me know if this helps.

Scott Kampa · Answer

Hello, 
 For the pump station related questions, pump stations will only show results if you are doing an Energy Cost Analysis or using the Combination Pump Curve tool. See this link for information on this. The best place to find the results for the pumps is by looking at the pump properties themselves. 
 The user notification about the conduits being under pressure appears to be calling out pressure pipe elements, which will be assuming to be under pressure by design. This user notification can be ignored. 
 However, given the setup of the model, I would recommend using a different solver. SewerGEMS includes all of the available solvers from the storm and sewer products. With a system like this, consisting only of a pressure system, the GVF-Convex (SewerCAD) solver would be the better option. 
 For more information on the different solvers available in SewerGEMS, see this link: Differences between solvers: GVF-Convex vs. GVF-Rational vs. Implicit vs. Explicit (SWMM) . 
 Regards, 
 Scott

Scott Kampa · Answer

Hello Marie, 
 The pump flow will be the value from the pump definition at the head required to balance the hydraulic grade at the discharge point. If you were to look at a profile, the hydraulic grade at the end of a pressure subnetwork would be at the crown of the last pressure pipe in the subnetwork. If the results look different than expected, you may want to review the pump definition and the headlosses in the pipes. 
 The pumps will not necessarily operate at the design flow. More information on pump operation can be found here . 
 I don't see the same results you are reporting in the model I have. If you have made changes to the system, a new copy of the model files will be needed. 
 Regards, 
 Scott

Scott Kampa · Answer

Hello Marie, 
 We don't get notifications if a model is uploaded, so that is the reason for the delay. 
 Regarding the pumps, there are no notifications and the model is converging so the results should be accurate. 
 For pump station PS-20B, both pumps are on and have a similar flow of around 286 gpm. This flow value is based on the head required to balance the hydraulic grade in the system. This basic information will apply to all of the pump flows in the model. This also happens to be the easiest one to show. 
 The pumps in pump station PS-20B are going to add enough head to the system so that after accounting for headlosses in the pressure pipes the hydraulic grade at the discharge point will be at the crown of the pipe or, in this case, the hydraulic grade of the downstream wet well W-1. The hydraulic grade here is 16 feet. So the head added by the pumps is what is required for the hydraulic grade at the wet well to be 16 feet while accounting for headloss. I would recommend creating a profile from W-6 to W-1 to see this. 
 For pump station PS-20C, both pumps are off. This is because the elevation in the associated wet well is set to a value where the pumps are off based on the pump controls (Elevation (On) and Elevation (Off)). 
 For pump station PS-20, only one pump is one based on pump controls. The flow here is higher than the design flow, but that is because of the head required so that the hydraulic grade at the outfall is at the crown of the pipe. Like before, a profile here may be instructive on what is happening. 
 For pump station PS-20A, both pumps are on, but the flows are pretty different. This is because the pump definitions for the two pumps are different as well. Assuming the pump definitions are entered correctly, the results here will be accurate based on the pump definition and the downstream conditions. 
 Regards, 
 Scott

Scott Kampa · Answer

Hello Marie, 
 There are no user notifications. Based on the input, I see no reason that the results are not accurate. 
 Regards, 
 Scott

Scott Kampa · Answer

Hello, 
 Like the other model, there are no user notifications. I see no reason for the results to be inaccurate based on the input. You will want to review the results, pump settings and wet well/outfall elevations to make sure everything is set up correctly. 
 Regards, 
 Scott