Laboratory Simulation of Geosynthetic Clay Liner Application in Contaminated Liquids Evacuation
Authors: Mlynarek J , Vermeersch OG , Lemelin D 
Published: March 2009

To prevent a contamination of soil and underground water by eaking mineral oil, recovery basins are designed and constructed in Quebec, Canada. The functions of such basins are to collect and to evacuate oil to a drainage and then to a recycled and treatment station. The material presently used for such an application is a concrete. However, due to difficult access to some of the transformers, and to the difficult low temperature conditions, engineers are looking for a new, alternate design idea. In order to evaluate the geosynthetic clay liner (GCL) hydraulic behavior in such applications, a laboratory demonstration test has been conducted. A full-scale model was designed and constructed for the purpose of measuring the rate of water flow through different layers of the proposed system. Mineral oil leaks as well as precipitation were simulated during the research program. The testing consisted of the measurements of mineral oil and water (precipitation) volumes at four levels of the demonstration model, during a period of two months. The results showed that only one percent of precipitated water and leaked mineral oil was collected underneath the geosynthetic clay liner. Further research is recommended on : - techniques of seaming of GCLs' joints and connections; - the minimum acceptance rate of hydration of GCLs for different liquids; - an influence of water content of soils on GCLs hydration; - a long term hydraulic compatibility of GCLs with different liquids and leachates.

According to the IFAI market report (1994) about 3,900,000 m2 of Geosynthetic Clay Liners (GCLs) were installed around the world in 1992, and the estimated surface for 1995 is 7,000,000 m2 in different fields of applications : - municipal waste containment systems 55% - industrial waste containment systems 15% - agricultural tanks 10% - mining waste 10% - municipal and industrial basins 10%

Among potential applications of GCLs, one presents a particular interest: the use of GCLs in mineral oil recovery basins. The function of a GCL in such an application is to avoid pollution of groundwater and soil by collecting and evacuating leaking oil to a drainage collection system.

Presently, such specific recovery basins for mineral oils are designed and constructed using a concrete material. However, in some situations this material seems to be not the most economical one. Indeed, due to the difficult access to some basins and to the difficult climate conditions, it could be less expensive and more practical to design an alternate recovery basins using geosynthetic materials.

GCLs are the materials considered for possible installation in this pplication. However, chemical compatibility of GCLs, and sealing properties of their seams and joints are of major importance.

Considering those facts, a research program has been developed and conducted using a full-scale laboratory demonstration chamber. The main objective of the project was to evaluate the hydraulic behavior of a commercial GCL in the application as a liner in the recovery basin.