What is the function of the gravel pack placed around the well screen?

The gravel pack placed around the well screen serves the critical function of reducing pumping sand. When water is extracted from the aquifer, the flow can destabilize the surrounding soil and sand particles, potentially leading to their entry into the well. The gravel pack acts as a filtration medium that allows water to flow freely while preventing larger particles like sand from being pumped into the well system. This is essential for maintaining the integrity of the well and ensuring a consistent water quality and supply.

Other functions mentioned in the options, such as filtering water, insulating the well, or cooling the water, are not the primary purposes of a gravel pack. While the gravel can provide some level of filtration, its primary role is to stabilize the well and protect it from sand and silt intrusion during the pumping process. This helps to extend the life of the well and to ensure that the water drawn from it remains clean and free from sediment.