Generally, the municipal solid waste landfills create lots of environmental pollution due to landfill gas combustion, leakage of leachate and foul smells. Among all these, leakage of leachate affects the surrounding environment the most, especially the surface and ground water bodies because the leachate consists of high concentrations of heavy metals, organic compounds and toxic contents. Recently, several cases have been reported around the world related to pollution of water bodies which were caused by municipal solid waste landfills [1]. The production and usage of heavy metals such as copper, cadmium and zinc have increased substantially over the years [2]. The excess quantity of heavy metals disposed off the land can cause significant damage to the environment and human health as a result of their mobility, solubility and their ability to transfer in water or plants [2, 3]. The leachate from MSW landfills may leak into groundwater aquifers due to rainfalls, spread into the adjacent river system by groundwater flow and pollute the surrounding environment. However, this process does not stop even after the landfill activities have stopped receiving solid waste. Hence, it is very essential to keep assessing and monitoring the surroundings of decommissioned landfill sites.

In the present study, column leaching tests were conducted with two leaching solutions, i.e., distilled water and 0.1N HCl + 0.1N EDTA to know their removal efficiencies of heavy metal ions of Cu, Zn, Ni, Cd, Pb, Fe and Cr present in the industrial sludge. It was observed that distilled water was able to remove only a few metal ions Cu, Zn, and Ni in lesser quantities. Using 0.1N HCl + 0.1N EDTA, all the heavy metals were leached out with removal efficiencies in the range of 71-98%. Using the results of column leaching tests, the migration rates of different metal ions were determined which can be used to design the soil washing programme at the site to treat the similar sludge.

Uncontrolled mining and the tailings produced can cause significant environmental impacts such as water, air, and soil pollution. In the present study, a contaminated soil of gold mines located in the Karnataka state of India was studied to know the geotechnical behavior of this soil as a foundation material and to suggest a suitable soil remediation technique to avoid contamination of surrounding water bodies. The in-situ dry unit weight of soil at the selected locations varied from 15.71 to 18.75 kN/m 3 . The effective shear strength parameters determined from Triaxial test results were in the range of 4.8 -8.2 kN/m 2 and 19.4 0 -29.8 0 , respectively, for the cohesion and angle of internal friction. The soil samples were analyzed for bearing capacity and settlement using GEO5 software tool, and the economical dimensions of the footings were estimated. It was observed that the soil has sufficient bearing capacity, and the settlements are within the allowable range. The chemical analysis of the soil samples showed that there are considerable amounts of heavy metals present in the mine soil. Though the strength of the soil is good, the contaminants in the soil may cause groundwater contamination and damages to the footings. Hence, the soil washing technique as a remediation technique was also studied through column leaching tests using different leaching solutions and found that diluted hydrochloric acid (HCl) with Ethylenediamine-tetraacetic acid (EDTA) can effectively remove the heavy metals from the soil.

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