Which of the following is used to properly seal a drilled well to prevent contamination of the water supply?

Using grouting to properly seal a drilled well is an effective method to prevent the contamination of the water supply. Grouting materials, which can include cement, bentonite clay, or other chemical compounds, help fill the annular space between the well casing and the surrounding geological formation. This space can serve as a pathway for contaminants to enter the well. By sealing this gap, grouting creates a barrier that protects the groundwater from surface pollutants and reduces the risk of environmental contaminants infiltrating the water supply.

The process ensures that there is minimal movement of groundwater, which can carry bacteria, chemicals, and other harmful substances into the well. A proper grouting technique not only provides structural stability to the well but also safeguards public health by maintaining the integrity of the water source.

In contrast, while other materials like epoxy and rubber seals can be useful for different sealing purposes, they may not provide the same level of protection against the specific risks associated with groundwater contamination as a well-constructed grouting process.