“…One literature review showed that the formation of leachates and their migration in an aquifer, despite the reclamation of old landfills, were serious problems observed in many countries (e.g., the United States of America, China, Italy, and Poland, e.g., [10][11][12][13][14][15]). Despite reclamation, the processes occurring in the stored waste, depending on many complex factors (moisture, temperature, redox conditions, pH, and types of microorganisms), lead to the formation of leachates and biogas, which affect the surrounding environment for a long time [16]. One of many examples is an unlined, closed municipal landfill on the alluvial plain in Norman (Oklahoma, USA), where the leachate plume extends at least 225 m downgradient in the unconfined, 12-meter thick alluvial aquifer [17] with a linear plume velocity of 40.2 m/year [18].…”