How do Taps and Laterals work in the storm and sewer products?

  Product(s): StormCAD, SewerCAD, SewerGEMS, CivilStorm
  Version(s): 08.11.05.xx and higher
  Area: Modeling

Problem

How do Taps and Laterals work in the storm and sewer products?

Video

Solution - Purpose of Taps and Laterals

A Tap is a type of node that connects the lateral to the conduit or channel. It enables the user to add inflows (via a cathbasin or property connection element) along a conduit or channel without the need to break the link element into multiple elements. There could be multiple lateral connections to a single trunk conduit or channel.

Although it can be used with manholes in a sewer model, the primary use of the Tap and Lateral element are road and site design engineers and OpenRoads users (see above) because this level of detail is more significant when working with a physical model. For example, an OpenRoads user (starting with the SS4 release as mentioned above) might need to use the Subsurface Utilities Engineering (SUE) clash detection tool, in which case the exact location of the lateral and tap is important. Since this is the primary intent of the tap and lateral feature, it is not recommended to use this in very large models, where Modelbuilder would be required to import a large number of taps and laterals.

Starting with the CONNECT Edition, a new Property Connection element was introduced, where a single node representing a property can be associated directly with a node on the trunk main.

Assumptions

Flow passes from the catchbasin or property connection down the lateral, to the tap and into the conduit. The flow from the tap is then contributed to the conduit or channel that it is connected to.

The location where the flow is assumed to enter the conduit depends on the solver and whether a property connection or catchbasin is connected to the lateral:

  • GVF-Rational (StormCAD) solver:
    • Property Connection OR Catchbasin: The flow from each lateral is assumed to enter the network at manhole or catchbasin on the upstream end of the connected conduit (not at the tap location)
  • GVF-Convex (SewerCAD) solver
    • Property Connection OR Catchbasin: The flow from each lateral is assumed to enter the network at manhole or catchbasin on the upstream end of the connected conduit (not at the tap location)
  • Explicit (SWMM) solver:
    • Property ConnectionThe flow from each lateral is assumed to enter the network at manhole or catchbasin on the upstream end of the connected conduit (not at the tap location)
    • Catchbasin: The connected conduit is internally split and the flow enters at the tap location (midway along the conduit).
  • Implicit solver: NOT SUPPORTED

Other assumptions:

  • Implicit solver: Taps and laterals are not supported in the Implicit dynamic solver. With the Explicit (SWMM) solver, laterals are treated as "dummy" conduits. The SewerCAD (GVF-Convex) solver does not perform any hydraulic calculations in the lateral pipe.
  • Licensing: In current versions above 10.00.00.40, laterals do NOT count toward your license limit. In version 10.00.00.40, lateral link elements do count toward your total number of pipes/links, which is checked against the number of available pipes in your license
  • Hydraulics and constraint-based design: hydraulics are not calculated in lateral elements as the flow simply gets injected into the connected pipe (via the tap) and it is assumed that the lateral sizes will be adequate. Therefore constraint-based design will not attempt to adjust the size/diameter of lateral elements. If you need to model hydraulics in lateral elements, either model them as conduits connected to the pipeline via a Transition node (which will split the pipe), or connect conduits between the cactchbasins and the upstream node of the main pipe (and use user defined length and inverts).

See Also

Using LoadBuilder to assign Property Connections to the nearest element while creating taps and/or laterals

How to toggle tap node dashed line display

Modeling Storm/Sewer Property Connections

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