Measuring the Engineering Properties of Landfill Leachate-Contaminated Soil

Industrial activities annually produce millions of tons of hazardous waste which are disposed eventually on landfills. In this study, the effect of saline industrial hazardous landfill leachate (SIHLL) contamination on the engineering properties of natural and contaminated silty clay soil was investigated in a laboratory program to assess the potentials of using this soil as a barrier for the lining of the saline hazardous industrial waste landfill. The contaminated specimens were prepared by mixing the natural soil with SIHLL at different concentrations (0, 25, 50, 75, and 100%). The results revealed that the permeability coefficient (K) and total pore volume of soil contaminated with SIHLL decreased as the SIHLL concentration increased from 0 to 50%. This was mainly due to the presence of high concentration of salts in SIHLL. The angle of internal friction (φ) of SIHLL-contaminated soil dropped from 24.95° (for 0% SIHLL) to 20.24° for 100% SIHLL, whereas this was not the case for the cohesion (C), where the value increased from 1.161 t/m² for 0% SIHLL to 3.705 t/m² for 100% SIHLL. A considerable decrease in consistency limits was observed for the contaminated soil at different SIHLL concentrations. Based on these findings, the studied silty clay soil can be feasible for construction of new hazardous solid waste landfill liner thanks to its low permeability and widespread availability in Egypt. The study recommends to carefully line the landfill with fully impervious liner materials to protect the soil and the groundwater from the leachate hazards.