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SewerGems - simulate flooding after pump failure

What we are trying to simulate is the storage volume in our network at ADWF flows after a pump failure into our WWTP.

So how long before we overflow at the lowest manhole elevation, and from that point, how much storage volume do we have on top of normal flows at ADWF.

We are using the Sewergems implicit engine, is this the best option?

Thanks

  • Hello Stephen,

    Here is the article which explains the differences between the solvers.

    http://communities.bentley.com/products/hydraulics___hydrology/w/hydraulics_and_hydrology__wiki/11852.sewercad-gvf-convex-solver-vs-sewergemscivilstorm-implicit-and-explicit-dynamic-solvers-vs-stormcad-gvf-rational-solver 

    The Implicit or Explicit solvers are best for analyzing problematic systems or flooding since they use dynamic numerical solvers that can calculate overflow rate and several other things.

    You also could use hydraulic reviewer tool to see the overflow in the wet well, which is available with Implicit and explicit solvers. Analysis>Hydraulic Reviewer. . 

    Regards,

    Sushma Choure

    Bentley Technical Suppport

  • Hello Stephen,

    Please also see the below newly created wiki about Wet well overflow modeling, which includes more information. 

    http://communities.bentley.com/products/hydraulics___hydrology/w/hydraulics_and_hydrology__wiki/32264.how-do-i-model-wet-well-overflow

    Regards,

    Sushma Choure

    Bentley Technical Suppport

  • Thanks but while that information is helpful, it doesn't solve our issue. Specifically, how do we simulate a pump failure with the SewerGems implicit engine AND the second part is then how do we calculate available storage in the mains downstream of the first overflow point. Obviously we could just look at length, volume, and size of pipes and work out how many hours storage we would have, but that only works for zero flow. What we are really trying to discover is, if the pumps fail at ADWF flows, how much available storage do we have until the first overflow point and what is the HGL of that outfall?
  • Hello Stephen,

    I would set the pump on and off elevations such that the pump does not turn on. Compute the model and animate some profiles of the area in question to observe what happens. You should be able to see from this when flooding first occurs and what happens afterward. Maximum HGL figures are typically also found in the properties of most elements.

    Additionally, you could graph the Overflow result field for your low manholes and/or add and sort on the overflow or "is overflowing ever?" results in a flextable.


    Regards,

    Jesse Dringoli
    Technical Support Manager, OpenFlows
    Bentley Communities Site Administrator
    Bentley Systems, Inc.

  • I personally like to draw a profile of the first several pipes upstream of the pump station and watch the HGL rise until it hits the first manhole rim and the second ...

    Depending on how flat the sewers are and what the HGL at the pump wet well is when the pump shuts off, you may be able to store a lot of water (or not) in the wet well and pipes.