When you hire a bore water drilling contractor, the first step they do is test and inspect a site to determine the type of groundwater and depth of the suspected aquifer. Notably, bore water comes from underground aquifers, which are fractured rocks with enough space to hold copious amounts of water. That said, a hydrogeologist must also determine the type of aquifer. The data helps a drilling contractor prepare adequately for a project. Here are the main types of bore water aquifers.
An unconfined or water table aquifer is formed when rainwater collects inside an impermeable rock through porous soil. One major characteristic of an unconfined aquifer is its proximity to the ground, making drilling quite inexpensive. However, proximity to the ground exposes the water table to fluctuating pressures and drought conditions. Thus, the availability of bore water from unconfined aquifers tends to fluctuate. If an unconfined aquifer is the source of your bore water, know that it will run dry during dry seasons. The uncertainty makes unconfined aquifers less reliable for businesses that need a constant water supply.
Unlike unconfined aquifers, confined aquifers (artesian aquifers) are surrounded by an upper and lower layer of semi-permeable and impermeable material. The configuration keeps bore water under high pressure; hence, drilling contractors must be careful when penetrating confined aquifers. The good news is that water quickly flows to the surface once you hit a confined aquifer. However, confined aquifers are usually found deep below the ground and typically take longer to drill than unconfined aquifers. Since confined aquifers are surrounded by impermeable ground material, it is crucial to determine their capacity before installing a bore well. Failure to determine an aquifer's capacity could leave you with a temporary well. In most cases, confined aquifers are reliable and guarantee a constant water supply.
As the name suggests, a semi-confined aquifer has the characteristics of a confined and unconfined aquifer. Typically, semi-confined aquifers are located close to an aquitard's edge or the thinnest section where the confining layer is highly permeable to allow more water through. When you drill through a semi-aquifer, the bore water will not flow upward to the surface because it is not under pressure. Notably, reaching a semi-confined aquifer usually indicates that a confined aquifer is close. Since the top and bottom of a semi-confined aquifer are permeable, they cannot hold water for long periods unless located in an area with a wet climate.