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connect two conduit with huge elevation difference

from the photo : they want to cover the whole area
the vertical distance = 17.9 m , the horizontal distance= 50 m.
what is the optimum way to connect this pipe to this box culvert.

Parents
  • Hello Mahmoud,

    This appears to be a pond with a culvert going under a road. What Bentley product are you using? in SewerGEMS for example it would be modeled as Pond > Headwall > conduit. See the section "Headwall as an alternative to a Pond Outlet Structure" in the following wiki article:

    Modeling Reference - Headwalls


    Regards,

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

Reply
  • Hello Mahmoud,

    This appears to be a pond with a culvert going under a road. What Bentley product are you using? in SewerGEMS for example it would be modeled as Pond > Headwall > conduit. See the section "Headwall as an alternative to a Pond Outlet Structure" in the following wiki article:

    Modeling Reference - Headwalls


    Regards,

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

Children
  • i am using stormcad.
    actually the box culvert was serving a small stream but they urbanize the whole area, and they want to cover the rest of the stream.

  • Hello Mahmoud,

    You would have to consider this urbanized area for modeling this culvert, if you have an existing model then you may need to modify the catchment properties. 

    Regards,

    Sushma Choure

    Bentley Technical Suppport

  • thanks sushma,

    i am aware of this point , but my question about connect the pipe to the box culvert despite the huge slope (about 35%)

  • First, I'll give a personal opinion. Surface streams are a resource and should be kept on the surface. The trend these days is to "daylight" old  storm sewers and convert them into beautiful surface parks and greenbelts. You can convey a much larger flood flow through a surface stream (with a tunnel under the embankment) as opposed to an underground pipe. But it's probably too late to do this in your project. You could build a nice waterfall at this location. See https://www.americanrivers.org/conservation-resource/daylighting-streams-breathing-life-urban-streams-communities/

    I'll now assume you have two pipe ends that are close to each other in plan view (50 m) but are vertically very different (18 m). A 34% slope will result in very high velocity.

    The simplest solution is to place a steeply sloping pipe between the two ends. You will get a fairly substantial hydraulic jump in the lower pipe/culvert when you transition back into a mild slope. Even though you can downsize the steep pipe based on hydraulics, it is best not to because debris, such as sticks, can get lodged in the transition from a larger upstream pipe into the steep pipe.

    If the steep pipe involves a great deal of excavation, then it may be better to lay the upstream section at a mild slope and install a drop shaft from the end of the upstream pie to the beginning of the downstream pipe. This may save excavation cost.

    I've heard of situations where steep pipes and drops can have problems with slugs of air moving through the system but I've never had to deal with them myself. You may want to do some research on this.

    Answer Verified By: mahmoud mahmoud 

  • thanks sir for this nice clarification