Which property affects the effectiveness of well points in draining groundwater?

The effectiveness of well points in draining groundwater is primarily influenced by soil particle size. This is because larger soil particles create larger voids and spaces between them, which facilitate the movement of water. When gravel or coarse sand is present, groundwater can flow more easily through these materials, allowing well points to effectively draw down the water table.

In contrast, smaller soil particles, such as clay, have much tighter packing and smaller voids, resulting in reduced permeability. This makes it more difficult for groundwater to move through, and therefore, less effective for well points to create a significant drawdown.

While other factors like soil moisture content, pH level, and temperature can impact various characteristics of soil behavior and water movement, they do not have as direct a role in determining the drainage effectiveness of well points as soil particle size does. Understanding this relationship is crucial for contractors when designing and implementing groundwater drainage systems in residential projects.