What characteristic of landfilling can pose a significant environmental risk?

Groundwater contamination is a significant environmental risk associated with landfilling because landfills often contain a variety of hazardous materials and waste products. Over time, leachate—liquid that has percolated through waste and carried dissolved or suspended materials—can seep into the surrounding soil and, eventually, into groundwater sources. This contamination can lead to harmful substances being introduced into the water supply, affecting both ecosystems and human health.

Many factors contribute to the potential for groundwater contamination in landfills, including the design and maintenance of the landfill, the types of waste deposited, and how well the leachate is managed. The risk emphasizes the importance of robust landfill management practices, including proper liner systems, regular monitoring of groundwater quality, and effective leachate treatment solutions.

While the other options—high cost of operation, difficulty in waste segregation, and space requirements—are relevant challenges faced by landfill operations, they do not directly relate to the environmental risks posed to water sources. The focus on groundwater contamination highlights a critical area of concern for public health and environmental protection within the context of waste management.