How should abandoned wells be filled to ensure they do not serve as a contamination channel?

The correct choice is to fill abandoned wells with naturally occurring soils and sealing materials. This method is critical for preventing contamination of the groundwater supply.

When abandoned wells are left unrepaired, they can provide a direct pathway for surface contaminants to enter the groundwater aquifers. Using naturally occurring soils and sealing materials helps ensure that the well is filled in a manner that mimics the surrounding geological formations. This approach not only restricts the flow of water but also prevents soil erosion and maintains the stability of the surrounding area.

Natural soils are designed to hold together and provide resistance to movement from contaminants, while sealing materials can help to create a barrier that reduces permeability. This prevents any surface contaminants from infiltrating the groundwater system.

Filling a well with water only does not provide a sufficient barrier, as water can flow through the well and allow contaminants to pass. Utilizing any available debris may introduce further contaminants and create instability. Filling with sand alone is also inappropriate, as it does not adequately seal the well and may allow for water movement through the sand layer. Proper filling with appropriate materials is essential to protect our water resources.