Entec has effectively used horizontal dewatering and remediation wells on a number of projects to help achieve objectives not realized with traditional vertical dewatering wells, such as increased water table draw-down and increased water production.
Water removal reduces construction problems associated with excavations below the water table. Horizontal wells can be used to replace or augment vertical wells when extracting large volumes of water from saturated formations. This technique allows the arrangement of multiple wells to curtain, or surround, an area.
These wells can be installed for various reasons, from reduction of groundwater flow into excavated areas (such as mines) to production of water for industrial process use or general use.
Horizontal wells can be installed with typical water well screens and pumps. Wells can be finished in a “blind” configuration or with well access at surface in two locations, allowing for pulled-in installation of multi-part well screens and one or two pumps per well. This allows for maintenance of the pumps to be performed with no required production down time. Full well restoration or redevelopment from end to end can be accomplished by a variety of contractors and is not restricted to water well drillers.
Areas where large volumes of water are required to be withdrawn and where little surface access is available are ideally suited to horizontal wells. A large cross section of the water bearing zone can be targeted effectively from only one or two surface locations instead of a very short vertical zone or intersection with the water bearing zone (as in the case of vertical wells). This additional zone intersection allows for measurable and significant decreases in the water table elevation.
Pollution extraction wells provide benefits similar to water extraction wells from horizontal well configurations. Larger volumes of water extraction result in better control of the diffusion or pollution plume. Horizontal wells also allow for more efficient “curtaining” of the plume and a reduction in the diffusion beyond the extraction zone.