What is the most common cause of groundwater contamination at a landfill site?

The most common cause of groundwater contamination at a landfill site is the leakage of leachate through a failure or deficiency in the landfill liner system. Leachate, generated from rainwater percolating through waste and the decomposition of waste materials, contains a complex mixture of organic and inorganic contaminants, including heavy metals, volatile organic compounds (VOCs), and ammonia. If the liner system, which is designed to contain the leachate, is compromised due to improper installation, punctures, tears, seam failures, or degradation over time, leachate can escape into the underlying soil and eventually reach the groundwater. This contamination can render the groundwater unusable as a drinking water source and pose significant risks to human health and the environment. Even properly designed and maintained liners can experience some degree of leakage over their lifespan, which is why groundwater monitoring is critical. For example, a small puncture in a geomembrane liner can allow leachate to seep into the groundwater, leading to elevated levels of chloride, benzene, and other contaminants.