Modeling a curb cut

  Applies To 
  Product(s): Bentley StormCAD
  Version(s): 08.11.XX.XX
  Environment:  N\A
  Area:  Modeling
  Subarea:  N\A
  Original Author: Jesse Dringoli, Bentley Technical Support Group


How do I model a "curb cut" in StormCAD, where flow leaves the gutter via a cut or notch in the curb, then flows into a ditch, vegatative swale, etc?


If checking spread and depth is not a concern and it is located in a sag position, one option would be to model it as catchbasin node set to 100% capture efficiency, connected to a conduit link element, whose shape is set to match the shape of the ditch. This can then be connected to where the ditch discharges to, or ended at an outfall. All runoff approaching the node will enter the link element. Ground, rim and invert elevations for the catchbasin node can be estimated.

If some bypass is expected, you may consider estimating the capture efficiency and entering that directly.

If you need to check depth and spread, you'll need to approximate with one of the available HEC-22 standard inlet types, such as a Curb inlet with width set to the width of the notch. This is needed in order for it to calculate what the depth would be to 'push' 100% of the flow through the opening. Another option would be to use the weir equation to estimate the depth given the approach flow. Spread can then be calculated from that along with the gutter slope.

See Also