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For every model there are two boundary conditions, one at the top and one at the bottom. The top boundary condition is usually the point of contact between the contaminant source (eg. a landfill) and the subsurface layers (deposit), and can be either:
• Zero Flux,
• Constant Concentration, or
• Finite Mass.
The bottom boundary condition is usually the point of contact between the deposit and either a much more or much less permeable strata (eg. an aquifer or bedrock) and can be either:
• Zero Flux,
• Constant Concentration,
• Fixed Outflow, or
• Infinite Thickness.
To edit the boundary conditions either select the Boundary Condition menu item from the Data Entry menu or click on the top or bottom boundary condition. The Boundary Condition form will then be displayed.
Depending upon the top and bottom boundary conditions selected, additional tabs will appear to enter the relevant data.