The suitability of the Libyan soils for use as engineered landfill liners
The quantity of waste generated in Libya, as in other developing countries, has been increasing dramatically for many years due to a rapid urban expansion associated with high population growth. Until now, this waste has been dumped into very large open tip sites located close to urban areas. These sites lack any form of engineered control system to prevent groundwater contamination and environmental degradation from the air and ground pollution. A high risk of groundwater contamination occurs in many water wells around the dumping sites. There is an urgent need to fmd an affordable and feasible long-term solution to protect groundwater supplies and the surrounding environment. However, the construction of engineered landfills usually requires the installation of a lining system. To be efficient, the lining system material should have a low hydraulic conductivity that should not increase under the action of leachates. This research provides a comprehensive physical and chemical laboratory investigation of an arid Libyan soil to assess its suitability in a landfill lining system. The clay mineralogy tested using XRD showed that compositions of all soil types tested are similar and are predominately illite and kaolinite. Batch equilibrinm testes were used to characterise the soil adsorption properties. The results of this assessment indicate that Libyan clays is not wholly satisfactory according to the criteria and guidelines available for landfill mineral liners. However, a bentonite was used to improve Libyan soils' performance as landfill liner. The results showed that bentonite improved the engineering characteristics of the Libyan soils tested, and proved to be a better additive as it lowered the hydraulic conductivity, and increased the adsorption capacity of the soils. Bentonite thus showed that it has the potential of being used as an additive to Libyan soils to improve its containment qualities.