Final answer:
A potential confined aquifer is indicated by a continuous layer of sandstone between impermeable layers, which can be identified within stratigraphic columns. The confined aquifer's location is contingent on the geological attributes demonstrated by the sandstone's continuity and overlying impermeable layers.
Step-by-step explanation:
When searching for a potential confined aquifer, we need to identify a water-bearing layer that is sandwiched between two impermeable layers such as clay or shale that can trap the water and create pressure. In a drill log with layers of sand, silt, and rock, the presence of a confined aquifer is likely indicated by a continuous layer of sandstone lying between less permeable layers.
In the hypothetical scenario, we examine the stratigraphic columns and look for laterally continuous sand layers that could function as the best aquifers. Ideally, a confined aquifer would need these sandstone layers to have an impermeable cover such as mudstone or limestone that acts as a confining layer. Taking this into consideration, the aquifer would likely be found below the first occurrence of a continuous sandstone layer that is overlaid by a less permeable layer such as the aforementioned mudstone.
Regarding the minimum depth for drilling a new water well, we must drill past the unsaturated zone and into the saturated zone of an aquifer where there is an adequate supply of water. This depth will vary depending on the geological characteristics of the site.