The CNC: GWT Constant Concentration Package pane is on the MODFLOW Features tab of the Object Properties dialog box.
The data that can be specified for the CNC package are the Starting time, Ending time, and Specified concentration and the Chemical Species. The Specified concentration is the specified concentration at the selected cells for the selected Chemical Species.
Specified Concentration Active is used to activate or deactivate
"Specified Concentration Active" can be used to turn on or off a CNC boundary. If the formula for Specified Concentration Active evaluates to True, a specified concentration boundary will be defined. If it evaluates to False, a specified concentration boundary will not be defined. This can be used to turn on or off specified concentration boundaries at different locations based on a criterion specified by the user. Such a capability can be useful for specifying tidal boundaries where some locations may be alternately flooded or exposed.
Specified Concentration Multiplier is only used if it has been activated in the CNC: GWT Constant Concentration Package Pane. If Specified Concentration Multiplier is specified, the concentration is multiplied by the Specified Concentration Multiplier value.
Starting time and Ending time are explained in the help for the MODFLOW Features tab.
