User Notification: "Number out of range. Looking for value that is less than lowest table value."

  Applies To 
  Product(s): PondPack
  Version(s): V8i, CONNECT Edition
  Area:  Modeling
  Original Author: Scott Kampa, Bentley Technical Support Group


When computing a model, the following user notification is generated.

"Number out of range.  Looking for value that is less than lowest table value.  Looking for ###.### ft.  Lowest table value ###.### ft." Engine Fatal Error"


"The vortex valve with the id '#####' is out of range. If using Downstream Channel tailwater type, make sure the channel has enough capacity."


The cause of this error message is that a component (such as an orifice, culvert, weir, or vortex valve) in a composite outlet structure has elevations set that do not match up with the headwater elevation range used for the composite outlet structure itself. This is most likely occurring with the composite outlet structure noted in the user notification itself, although it can sometimes be more general and be referring to a different composite outlet structure.

Steps to Resolve

Note the name of the outlet structure that is causing the issue in the list of User Notifications. Next, go to Components > Composite Outlet Structures and find the composite outlet structure associated with the outlet structure in the User Notification.

Next, review the elevations for the headwater range of the Composite Outlet Structure and make sure that they match up with the elevations of the pond associated with the Composite Outlet Structure.

If the outlet link element has "Use Elevation-Flow-Tailwater Table" set to "Yes", then check the selected EQT table to make sure the headwater range matches the upstream pond elevation range, and that the tailwater range matches the downstream pond's elevation range. For example, if the pond elevation is from 10 feet to 20 feet, then the headwater portion of the EQT table needs to range from 10 to 20 feet.

If using a composite outlet structure, the elevations for the Composite Outlet Structure may be outside of the range of the pond elevations, and will need to be resolved before the model will compute. This can happen for example if the wrong pond is selected in the "Pond" field of the headwater range, when the headwater type is set to "Use pond for headwater range".

Next, check the elevations in the outlet structure components (weirs, orifices, etc) and ensure that they are within range of the pond. One common confusion is with irregular weirs - the elevations in the irregular weir cross section table are added to the "elevaiton" field in the weir properties.


The maximum value on the vortex valve curve is 6 ft. at 0.29 cfs., but if you look in the screen shot below the total difference in headwater range is 6.24 ft., which is not covered by the curve. If you add in one valve of 6.24 ft. with a flow of about 0.30 cfs this problem would be resolved and the model would run.  

On rare occasions, this user notification may be related to a different outlet structure than the one referenced in the User Notification. If the headwater range in the Composite Outlet Structure is the same as the pond for the outlet structure element referenced in the user notification, please do a careful review of the other outlet structures in the model to make sure that the headwater range of the associated Composite Outlet Structure matches that of the referenced pond. It is possible that the incorrect Composite Outlet Structure is being used for a given outlet structure.

See Also

Fatal error when using Downstream Channel option for outlet structure tailwater