Unconfined Aquifer

Definition - What does Unconfined Aquifer mean?

An unconfined aquifer is defined as a body of water formed from ground water, rain water run off and streams with its water table, or the upper surface, open to the atmosphere. They can be problematic as they fluctuate under atmospheric pressure. These aquifers also form at a faster rate than confined aquifers. In the context of trenchless technology, the presence of unconfined aquifers can challenge trenchless construction in several ways. Unconfined aquifers have clay, sand and gravel layers which can complicate the process of dewatering an area where drilling or microtunneling is to be carried out.

Trenchlesspedia explains Unconfined Aquifer

Aquifers are formed when groundwater or run off seeps through permeable rock and soil until it reaches an impermeable strata of rock or reaches the earths surface. The water from unconfined aquifers is mainly used for domestic and agricultural purposes. Because unconfined aquifers are open to the atmosphere they carry a greater risk of contamination. Unconfined aquifers can be found below rivers and streams. They consist of layers of sand, limestone and gravel. This scenario makes it challenging to carry out directional drilling or microtunneling due to the variation in soil density which can cause over excavation or create instability.

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