Vertical wells along shorelines have similar issues to the wells in thin aquifers noted above, in that their productive zones are limited and it usually requires many wells to achieve useable volumes. These structures are also prone to damage from storms and flooding. More sophisticated solutions include the Ranney collector type of well, with radial, horizontal laterals connecting to a central caisson.įisheries agencies are becoming more demanding in the construction and ongoing maintenance of intake weirs that directly pull water from rivers and lakes, as protection of fish habitat is becoming an increasingly contentious issue. Groundwater in Connection to Surface Waterįor communities adjacent to large bodies of surface water, such as lakes, reservoirs or rivers, water may be obtained directly from the body, or from multiple shallow wells installed along the shoreline. A vertical well network contains not only a high ratio of non-screened, non-productive casing, but each well requires its own pump, and the water must be conveyed to a central facility with multiple trenched pipelines. Further, the horizontal well requires only one pump, and limited transfer piping to convey the water to distribution or treatment facilities.
The ratio of productive, screened well to unscreened riser casing is many times that of a single vertical well, and even more favorable compared to a network of vertical wells.
Horizontal directional drilling full#
A single horizontal well may be several hundred, up to a couple thousand feet long, intersecting the aquifer for most of its length and spreading the cone of depression along the full length of screen.
In contrast, horizontal wells are ideally suited for these aquifers. In coastal or island communities, saltwater intrusion is a classic problem ? overpumping of the ?bubble? of potable water floating above a brackish or saline layer can cause irreparable damage through saltwater intrusion.
Horizontal directional drilling install#
Multiple wells, spaced at intervals and pumped at lower rates may provide a more continuous water supply, but are costly to install and maintain. Production of viable quantities of water from these formations can be challenging with vertical wells ? drawdown at even minimal pumping rates quickly exhausts the supply adjacent to the well, with the potential for damaging the formation. In some locales, the best groundwater reserves are situated in thin, sinuous buried stream channels. Many coastal or island communities, and some desert municipalities, must tap thin, shallow or vertically constrained perched aquifers for their water supply. In contrast, a network of vertical wells drilled to intercept the same volume of aquifer would require multiple rig setups, multiple wellheads, and hundreds of feet of non-productive riser casing. Shallow HDD bores typically are started from the surface at an acute angle, and are guided to a subsurface or remote surface target using sophisticated electronics packages that enable the driller to navigate and steer the drill along a desired path.Ī shallow, 50-foot deep well takes approximately 200 feet to achieve the target depth, but may be hundreds or even in excess of 1,500 feet in length.
Unlike the deep directional bores used in oil exploration and production, which can extend thousands of feet deep, shallow HDD is performed from just a few feet to a few hundred feet beneath the ground surface. Meanwhile, a relatively new technology, shallow horizontal directional drilling (HDD) for utility and pipeline installation, has evolved rapidly over the past three decades. Even the venerable cable tool rig is still used for this purpose in some locales. Despite mechanic?al advancements in advancing a borehole, however, the extraction technology has remained the same: drilling and casing a vertical bore that intercepts a water table. Shovels gave way to cable tool rigs in the early 1800s and mechanical improvements incrementally led to current well-drilling technology, typically rotary drive rigs with automated casing drivers. The technology for extracting groundwater from subsurface resources hasn?t advanced appreciably since drillers abandoned shovels and buckets for mechanized well drilling rigs.
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