Heat mitigation in geosynthetic composite liners exposed to elevated temperatures

The hydrothermal behaviour of single and double composite liners subjected to elevated temperatures is examined. Particular interest is given to the effect of the presence of wrinkles in the geomembrane (GMB) as well as defects, and the existence of a gap between the primary and the secondary liners caused by the presence of a leak detection system. Heat flow resulting from elevated temperature was found to be mainly influenced by the size of the air-filled gaps present within the composite lining systems. The larger the air-filled gap size, the lower was the heat flow through a barrier system. The presence of a leak detection layer (i.e., large air-filled gap) and GMB layers were found to be the primary factors to reduce heat flow substantially through the lining systems. Therefore, the presence of a leak detection layer combined with a secondary GMB can improve the overall thermal insulation capacity of a double liner system, minimise heat flow through the secondary liner and offer the possibility of protecting the GCL (if present) and the subgrade from possible heat induced drying/desiccation. A leak in the geomembrane can minimise the gain in thermal insulation. However, this effect can be reduced if the liquid is regularly pumped out.