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Manifold Force Mains with Many Pumps

I'm working in a coastal community where the terrain is very flat and therefore they don't have much gravity and they use a lot of pumping stations. They have 100's of duplex submersible pump stations and 1000's of individual grinder pumps that all pump in common force mains, some of which even reverse directions under various operating conditions. The system even has several in-line sewer booster pumping stations along the force mains. They have multiple treatment facilities and use the in-line booster PS to try and move flow to various treatment plants to optimize available capacity. The in-line boosters also serve to shift the 'natural' hydraulic breaks in the system to alleviate some areas where the head conditions get too high pushing the pumps back on their curves. 

I want to model this complex system but I'm researching the best solutions. Is this best handled in a water modeling software or wastewater? And what level of detail is necessary to really provide the most benefit for the model? We would like to use this for operational modeling to evaluate transfer flow in different directions and optimize the system, as well as evaluate the impacts from future connections. Do we need to model detailed pump curves for all the duplex PS, and wet wells with controls for a EPS model? How important are the air valves in the system? Or is it possible to simplify the system? And how do you account for the smaller individual grinders which are just small PD pumps that pump at relatively fixed flows under higher head conditions? They do have good SCADA data on many of the duplex PS and pressure points within the system to help validate a model.

Any users out there with experience in modeling a similar system? Or any thoughts on water vs. sewer software for this application and the level of detail needed to provide optimum benefit for operational modeling?

Thanks,

-Brian

  • Hello Brian, 

    Using GVF Convex solver with SewerCAD or SewerGEMS would be helpful in your case, there are multiple similar forum threads available here to go through. 

    About modeling booster pumps along with several submersible pump stations, it would be better to model them as regular pump stations. 

    Below wiki will help you in modeling the submersible pumps and how to input data for that. 

    Modeling a submersible pump 

    About simplifying the model, you don't need to model multiple grinder pumps individually since it would increase complexity of the model with these multiple pump stations and wet well with multiple pumps turning on off. You could add them as inflows going to the manholes where you can specify them as loading unit counts for your records of number of grinder pumps added.

    Please go through the below similar discussions on such systems, which will help you proceed further, 

    Low Pressure Sanitary System 

    SewerCAD - Grinder Pump Pressure Model 

    If you have details about the pump curves for these PS then it would be beneficial to add those rather than adding them as single point pump curves for better modeling and stability of the model, same goes for wet wells you would need operating levels of these wet wells to be specified. 

    In SewerGEMS you have ability to import SCADA data and analyze the system just like WaterGEMS, so that SCADA data can be utilized as well. 

    SCADAConnect in SewerGEMS 

    Air valves in the model can be installed at the high points as required to overcome the negative pressures, see below wiki for reference. 

    Modeling Force Mains with Air Valves in SewerCAD (GVF Convex Solver) [TN] 

    Regards,

    Sushma Choure

    Bentley Technical Suppport