What is a requirement for a well-point and sock/horizontal pump system to function optimally?

A well-point and sock/horizontal pump system is designed to effectively lower the water table and remove excess groundwater during construction activities, especially in areas where soil moisture can impede operations. For this system to function optimally, it is crucial that the soil allows for efficient water movement. Sandy soils possess larger particle sizes and greater porosity compared to other soil types, which facilitates faster drainage of water. This characteristic allows the well-point system to effectively draw water away from the excavation site, maintaining a dry work environment.

In contrast, clay soils have fine particles and are much denser, leading to poor drainage and slower water movement. Rocky terrains can present significant challenges for the installation of well points due to the difficulty of penetrating the ground. Loamy soils, while having good drainage properties, do not perform as efficiently as sandy soils in the context of a well-point system. Therefore, the optimal functioning of a well-point and sock/horizontal pump system is significantly enhanced when it operates in sandy soils, making this the best choice among the options provided.