The well drilling process requires considerable skill to penetrate sand, gravel and clay layers to reach an aquifer. A water well drill must withstand immense pressure as it is driven into the ground.
A steel driving point fitted to the lower end of tightly connected pipe sections is pounded into the ground, often with a rig, until it penetrates an impervious layer below the surface.
Cable Tool Drilling
When drilling a well with the cable tool method, a heavy metal hammer suspended from a wire cable is repeatedly raised, turned, and dropped. It pulverizes the rock, forming a borehole through which water can flow. As the hole drills, bailers or buckets are lowered to collect the crushed rock material (called “cuttings”). The cuttings are removed from the well through an evacuation tube, separated from the drilling fluid. The drilling fluid, usually a mud mixture of oil or synthetic oil and water, is recirculated down the pipe and back up to the surface for cleaning and blending with fresh mud for repeated use.
During drilling, samples of subsurface materials are collected and preserved in labeled sample bags for analysis and correlation to the geologic log. This sampling provides a better picture of the geology of the formations penetrated than any other drilling method. This information can help to avoid expensive mistakes and delays. Each Tampa well drilling that is dug, and each pump that is installed must be done so expertly if a good water supply service is to be provided.
Rotary Drilling
Rotary drilling uses a hammer-type bit to drill down through the sand and gravel to an aquifer. A steam, diesel or gas engine powers the rig. It may also have a generator that generates electricity on-site to power the pump. As the rotary drill moves through the formation, water-based drilling mud is pumped into the hole to keep the borehole open. This fluid lubricates the drill, reduces heat, cleans the bit and helps to remove the drilling cuttings. Well points are fitted to the lower end of tightly connected pipe sections and driven by method up to 10 m depth or by a power drive to deeper depths. Once the aquifer is reached, the well is developed by surging or instant pumping until sand-free water is obtained. The well is then lined with casing to prevent collapse. The well should be located away from contaminants such as animal feedlots, buried fuel tanks, waste disposal and septic systems.
Jet Drilling
A nozzle at the end of a narrow pipe is jetted with water to loosen sediments carried back into the existing well hole. The method is similar to percussion drilling but can reach deeper, more dense geologies that are difficult to dig with rotary drills. A driven well consists of steel pipes driven into the formation using a drive block, either hand-driven up to 10 m depth or operated by a cable tool rig for deeper wells. The method best suits unconsolidated sand formations relatively free of cobbles and boulders. To drive a well, start by selecting an out-of-the-way site. It should be at least 5 feet from structures such as septic systems, buried fuel tanks and waste disposal units that may contaminate groundwater. Then, dig a shallow trench that slopes downward from the tripod, about 1 meter wide and deep. Fill the trench with water for jetting and set up the water pump.
Auger Drilling
This well-drilling method is useful in soft, unconsolidated material or weak weathered rock. It is less expensive than RAB drilling but achieves shallower depths than rotary drilling. This technique uses compressed air to drive a down-hole hammer that destroys the rocks it encounters. It allows the drill to continue without stopping to clean out the hole. However, the drill produces a lot of waste that must be removed from the site. Once the water table is reached, a conductor casing is set. The drilled hole is then backfilled with earth. Open-Hole Logging Tools can be run in the well to record information about the subsurface formations. Before you dig a well, talk to your local county agricultural extension office and find out what kind of soil is on your property. Also, review geological surveys and state well drilling records to determine how deep previous wells were drilled and whether or not they found water.
