Final answer:
Modern landfills use a combination of liner systems, leachate collection systems, monitoring wells, cover systems, and gas collection systems to protect groundwater from contamination.
Step-by-step explanation:
Modern landfills are engineered with several features to protect the groundwater from contamination. The first line of defense is a liner system, which includes a combination of clay and synthetic materials to prevent leachate, a polluted liquid, from penetrating into the soil and reaching the aquifers. Additionally, modern landfills incorporate a leachate collection system to manage and treat any liquid that does accumulate.
Furthermore, these facilities use monitoring wells around the perimeter of the site to regularly test for any signs of groundwater contamination. The cover systems reduce infiltration of water that could carry contaminants down into the ground, and gas collection systems minimize the release of methane and other gases which could also indirectly affect groundwater quality.
To ensure long-term safety and compliance with environmental regulations, the operation is closed with an impermeable cap, and post-closure monitoring continues to check for any signs of groundwater contamination. These combined technologies and methods work together to minimize the risk of contaminating groundwater sources that are essential for human consumption and natural ecosystems.