System.ArgumentOutOfRangeException: Specified argument was out of the range of valid values.

  Applies To 
  Product(s): Bentley SewerGEMS, Bentley SewerCAD, Bentley CivilStorm
  Version(s): 08.11.05.XX
  Environment:  N/A
  Area:  Output and Reporting
  Original Author: Craig Calvin, Bentley Technical Support Group


After computing a model an error appears stating "H&H-SewerGEMS stopped working".
Clicking on the button outlined in red above will display the Exception.log file with the following message:

"System.ArgumentOutOfRangeException: Specified argument was out of the range of valid values.
Parameter name: Index was out of range.  Must be non-negative and less than the size of the collection.
Actual value was -1."


The above errors may be due to RTK values in a RTK Table.

Make sure all values used are within an acceptable range (Components menu > RTK tables).


The RTK parameters are:


R - fraction of precipitation that enters the collection system for that component

T - the time from the precipitation pulse to the peak of that component of the hydrograph

K- the ratio of the time to peak to time to end of hydrograph for that component.



  • K is usually on the order of 1.5 to 2.5.
  • The sum of the R values for all components should be positive but less than 1.
  • The default units for T is hours while R and K are dimensionless.
  • The error above will appear if a T value less than 1 minute is entered.

See Also

SewerGEMS Help Article "Assembling RTK Parameters"

  • Created by
  • When: Mon, Aug 17 2015 1:21 PM
  • Last revision by
  • When: Thu, Oct 22 2015 1:22 PM
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