Mitigating Leachate Contamination: Geological Investigations at Alue Lim Landfill Area, Lhokseumawe City

Abstract Geological studies are essential for identifying potential pollution in the Alue Lim Landfill Area, Lhokseumawe City. This research focuses on the physical properties of rocks, soil structure, and specific geological layers that influence water movement. The permeability and porosity of rocks are critical factors determining the ease with which leachate penetrates and migrates through geological formations. The study area encompasses the Idi formation sandstone unit (Qpi) and alluvium deposits (Qh). The Idi formation sandstone unit is characterized by fine to medium grain sizes (0.125 - 0.25 mm), interbedded with coarse sand, and exhibits a range from well to poorly sorted, moderately rounded grains with good porosity and permeability. Conversely, the alluvium deposit unit consists of clay, sand, and gravel, where the clay deposits are well-sorted with grain sizes >1/256mm, displaying poor porosity and permeability (range from 35% to 80%), and a clastic texture. The interaction between the permeable sandstone layer of the Idi Formation (aquifer) and the impermeable clay deposits in the alluvium unit (aquiclude) significantly affects leachate movement through the subsurface. Leachate rapidly migrates through the porous materials such as sand and gravel in the sandstone layers, potentially spreading contamination. In contrast, the clay layers act as barriers, limiting and redirecting leachate flow within the alluvium deposits (to the west and south). This research provides crucial insights for recommending management and mitigation strategies to address groundwater pollution in the Alue Lim Landfill Area.