EPANET Modeling for Force Main 1

[brainsplease]

I am connecting to an existing force main with another lift station and I am needing to analyze the effects of the pumps acting together. I have seen this topic mentioned quite often on the forum, but I have not seen any details on how to accomplish this. I have used EPANET for water distribution systems, but never for a sanitary sewer system. I know there are better programs to accomplish my task, but considering EPANET is free, it is my current preference. My biggest question is how do I model the discharge of the force main into the manhole? EPANET has input for node demand, but considering I want to know what the two pumps will provide to the node (one pump will influence the next so I dont know the operating points), I cannot provide input for demand; unless my reasoning is incorrect. Also, I am not entirely sure how to model the wetwells. In a nutshell, I dont really see how EPANET can be used for this purpose. Any ideas?

 

[CrazyHorse81]

brainsplease - i don't know if you have found a program to represent your forcemains, but...EPA does have freeware to model storm and sanitary sewers or combination sewers with the capability to model lift stations

try this web site

http://www.epa.gov/ednnrmrl/models/swmm/index.htm

good luck

 

[vodeni]

Depends on how accurate you want to be. If you want to use SWMM as CH81 suggested, there are some limits to pressurized flow, but it could be done. I would give it a shot. I used SWMM in complex systems with multiple pump stations/force mains and gravity sewers, but that was more for planning purposes, total volume of flows etc, not to try to design pump station or define design points for pumps.

If you are using EPANET for wetwell use as storage tank/reservoir with either constant head or change. Iwould instead of a discharge manhole also use a reservoir with zero head (or whatever the elevation is there)but unlimited surface/volume so it would take forever to change the head. That way you would always keep atm. pressure at your discharge and have pumps working all the time.

 

[semo]

vodeni is correct.

Use a reservoir for your pump input node. Set the head at the low water level of your wetwell.

Set a curve for your pumps and model the pump using the appropriate curve.

Model your forcemain as you would waterlines.

Model the discharge as a reservoir with a head equal to the discharge elevation of the forcemain.

You can run it as static and the report will show the draw from each reservoir.

You need to run the system with all pumps but one off as well to see where the operating point falls on the curve when no other pumps are on.

No need to set demands at any nodes.