SIMULATION OF THE WICKING EFFECT IN A 2-LAYER SOIL LINER SYSTEM

A series of simulation runs were made using the computer model VSAFT2 (Yeh & Srivastava 1990) to estimate the ''wicking'' potential of five low-permeability liner materials including excel, celite slurry, kiln dust, rock creek clay and celite waste. The unsaturated hydraulic prop erties for these materials were assumed to be represented by the van G enuchten model (1978). The hypothetical liner system simulated consist ed of 0.305 m (1 foot) of low permeability material underlain by a med ium sand. The purpose of this modelling effort was to quantify the eff ects of liner thickness and leakage rate on the lateral spreading of t he wetting front, and to determine the effectiveness of the diffusivit y function in predicting the migration of the wetting front. Results i ndicate, as expected, that the liner material with the lowest permeabi lity retards vertical movement the most; however, the horizontal wicki ng effect is also limited. Additional multi-layer liner systems will b e simulated in the next phase of the project to improve liner wicking performance. (C) 1995 ISWA