The aquifers present at landfill sites are often at risk of contamination due to leachate percolation from the dumpsites. The current study examines the case of Achan, the only engineered landfill in Srinagar, Jammu and Kashmir. The characterization of soil was done by evaluating various geotechnical properties of soil. The heavy metal composition of leachate and groundwater samples were determined for two seasons to understand the seasonal variation of heavy metal concentrations. The analysis revealed an alarming contamination of water due to heavy metals, particularly lead. The concentration of lead in water samples exceeded the allowable limit (0.01 mg/L) prescribed by Bureau of Indian Standards (BIS) and World Health Organization (WHO). The isotherm and kinetic studies, to understand the surface characteristics of soil, were done by performing batch adsorption experiments. The batch adsorption test was optimized by considering different factors like pH, optimum adsorbed dosage, initial concentration, and equilibrium time. It was concluded that the soil at the landfill follows pseudo-second-order kinetics (R2 = 0.999), implying the sorption mechanism to be chemical in nature. The Langmuir isotherm model showed the best fit (R2 = 0.9731) for the soil sample. The maximum lead uptake capacity of the soil came out to be 160 mg/kg, and the overall removal efficiency was observed to be in the range of 77–87%. The higher lead uptake potential of soil can be attributed to the presence of higher fines content of 84% with a silt fraction of 52.5%, and a clay fraction of 31.5%.