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If a geomembrane is present this tab is used to edit the data for the geomembrane. The following data can be edited on this tab:
Name: This is the name of the geomembrane layer. It is used only for drawing.
Symbol: This is the symbol used to draw the geomembrane. To change the symbol click on the Change Symbol button. A Change Symbol form will be displayed where you can change the bitmap library, bitmap, foreground color, background color, and fill size for the symbol.
Thickness: This is the thickness of the geomembrane.
Diffusion Coefficient: This is the diffusion coefficient of the geomembrane. See Rowe et al (2004) for a discussion of this parameter and a table of typical values.
Phase Parameter: This is a dimensionless phase parameter, ‘KH’ or ‘Sgf’,. The default is one; this represents no phase change. See Rowe et al (2004) for a discussion of this parameter and a table of typical values for common contamants and HDPE geomembranes.
Leakage Method: This is used to select the method for calculating the leakage through the geomembrane. It can be calculated using the equations by Roew et. al., 2004 for either a circular hole in a geomembrane in direct contact with the foundation (similar assumptions to Giroud but allowing one to consider more variables) or for a wrinkle (or series of wrinkles) with holes (the most realistic situation for many applications); Giroud & Bonaparte, 1992; or specifying an equivalent hydraulic conductivity.
Equivalent K: If the method used to calculate the leakage through the geomembrane is Equivalent K, then this parameter will be displayed. This is the equivalent hydraulic conductivity of the geomembrane. If you are unsure what the value of this is, it is recommended to use a leakage rate landfill. Note: that the use of an equivalent K is a device for convenience of calculation and in no way represents the true leakage mechanisms. We recommend that you use the leakage equations. See Rowe et al (2004) for a discussion of leakage equations.