Water wells are an essential part of most properties worldwide nowadays. There are various methods used for drilling water wells, including cable, rotary and auger drilling. Auger drilling is typically used in very soft rock and soils. It drills holes by rotational penetration into the ground using a drill bit.
Cheap, fast, and easy-to-use, it is perfect for use on soft, non-consolidated, or semi-consolidated soil, as well as weak and weathered rocks. However, auger drills can also be used to drill mine shafts, again depending on the type of soil.
Well drilling augers are usually used to create water bearing wells for isolated communities that might not have access to heavy equipment. However, not all augers can be used to drill wells, as water penetration can affect different types of auger. Water well drilling should use the correct type of auger.
There are different auger-drilling bits used by well drillers. Some drillers will use different drills for the upper and lower borehole parts while others will use one for the entire drilling. Here are the different augers used for drilling water wells.
Solid Stem Augers
Solid Stem, or Solid Flight Augers, are continuous-flight augers driven using top-drive rotary machines with slow rotation and adequate torque rating. Solid stem augers are used for small-diameter deep holes. Their cuttings are held up by the hole, and then conveyed to the surface by rotated helical flights.
The flights are usually advanced into the ground with the use of a claw bit. As the drill bores deeper into the earth, the claw bit displaces the soil and moves it up the flight and onto the surface. Solid Stem Augers are perfect for rapid drilling in soft and semi-consolidated soil, with the ability to bore down to 400 feet. Its ability to bore deep also makes it perfect for collecting samples.
Because it requires no circulation liquid, solid stem augers can be used on clay soil. However, solid stem augers are not suited for loose or sandy soil, or for boring down below the water table.
If solid stem augers are used for your drilling, the well’s permanent covering is installed after removal of the augers.
Hollow Stem Augers
These consist of continuous-flight augers with hollow centre tubes. Hollow stem augers are typically used with bit plugs attached to secondary internal rod strings. Hollow stem augers are usually used for drilling in soft soil conditions like swamps, as the hollow stems acts as a temporary casing that prevents the hole from closing.
Much like the solid stem auger, hollow stem augers are fast, easy, and cost-effective to use. The hollow stem also allows crews to collect uncontaminated samples from the soil. Hollow stem augers, however, are limited to loose, sandy, or unconsolidated soil, as it becomes ineffective when it encounters rocks, cobble stones, or boulders. It also has a limited depth, roughly 150 feet.
The augers drill the well in the same manner as continuous-flight augers to its required depth. After reaching this depth, the inner rod strings are withdrawn, and you can install your permanent casing before removing the augers.
Bucket augers are short, helical augers that use a metal tube to help hold the cuttings during withdrawal. When drilling using bucket augers, the cuttings are removed from the hole with a bucket and hoisted to the surface.
Bucket augers can also be used with an extension cute. This enables the driller to provide an accurate amount of material, which helps crews measure a precise distribution of soil quantity and location. The chute is usually synchronised with the auger, opening automatically once the drilling starts. Bucket augers, however, require a hydraulic motor and a set of hydraulic auxillaries to operate it, making it more complicated to use than other types of augers.
Bucket augers can be installed on a number of common equipment, making them versatile. It can also be used for trench back filling, which is the act of filling up trenches with the material that was removed prior.
As the hole gets deeper, extensions are added to the bucket auger. Bucket augers are also a great indicator for the presence of hard objects like rocks and boulders. It can also be used to detect materials in the hole that have a risk of cave-ins during excavation. Though inexpensive, bucket augers are only used for large diameter, shallow wells that measure 24 to 36 inches.
There are many advantages of the auger water well drilling methods mentioned above over other types. Auger drilling, for instance, has low operating costs and a fast rate of ground penetration. It also does not contaminate your ground water when drilling hence you can be sure of your water’s safety.
Determining the type of auger to use for your construction project requires an understanding of the type of soil you’re working with, the environmental impact of your project, and the depth requirements of the project. Always consult with engineers about the type of auger to use for your project, as they can tell which auger is best suited for the job at hand.