AL Well Driller key terms

The gap between the outside of the well casing and the wall of the borehole. It is filled with grout or sealing material to prevent surface water and shallow groundwater from moving down the well.

A cement-based or bentonite-based mixture pumped into the annular space to form a solid, low-permeability seal. Proper grouting protects groundwater quality and stabilizes the casing.

A mixture of Portland cement and water with no sand or aggregate, commonly used to seal well annuli. It sets hard and provides a strong hydraulic barrier against contamination.

A clay composed mainly of montmorillonite that swells when wet. In well work it is used in drilling mud, as a grout component, and as a sealant in annular spaces.

A pipe lowered to the bottom of the annular space through which grout is pumped upward from the base. Placing grout from the bottom up avoids voids and dilution.

Pipe installed in a borehole to keep the hole open, prevent caving, and isolate the well from unwanted water or contaminants. It may be steel or plastic and is often grouted in place.

A slotted or perforated section of casing placed opposite a water-bearing formation. It allows water to enter the well while holding back sand and gravel.

Sorted gravel placed in the annular space around a well screen to filter formation material and improve yield. It reduces sand pumping and helps stabilize the borehole.

A buildup of sand, silt, or gravel inside a well that blocks flow or traps equipment. It can reduce yield and may require cleaning or redevelopment.

The process of removing drilling mud, fines, and loose material from a new well so it produces clear water at maximum yield. Methods include surging, jetting, and air lifting.

A well development or pumping method that injects compressed air into a submerged pipe, lifting water and sediment to the surface. It helps remove fines from the formation near the screen.

The hole drilled into the ground for a water well before casing is installed. Its diameter, depth, and straightness determine what casing and screen can be used.

A drilling method that turns a bit on the end of a rotating drill string while circulating drilling fluid to remove cuttings. It is common for deep or large-diameter water wells.

A percussion drilling method that repeatedly lifts and drops a heavy chisel bit to break rock, with a bailer removing cuttings. It is suited to hard rock and boulder formations.

A fluid mixture of water, clay, and additives circulated during rotary drilling. It cools the bit, carries cuttings upward, and coats the borehole wall to control caving.

The depth to water in a well when the pump is off and the water has stabilized. It indicates the natural groundwater level at that location.

The depth to water in a well while the pump is running steadily. It is lower than the static level because pumping draws water down around the well.

The drop in water level in a well caused by pumping. It is the difference between static and pumping water levels and reflects the well's efficiency and aquifer response.

The well yield expressed per unit of drawdown, usually gallons per minute per foot of drawdown. A higher value indicates a more efficient well and productive aquifer connection.

The volume of water a well can produce per unit of time, commonly reported in gallons per minute. It is determined by pumping tests and depends on the aquifer and well design.

A controlled pumping of a well to measure yield, drawdown, and recovery. Results guide pump sizing and show whether the well meets its intended use.

A geologic formation that stores and transmits enough groundwater to supply wells. Sand, gravel, sandstone, and fractured rock are common aquifer materials.

An aquifer trapped beneath a low-permeability layer so its water is under pressure. A well tapping it may rise above the top of the aquifer, sometimes flowing at the surface.

The upper surface of the saturated zone in an unconfined aquifer. Its depth below ground changes with rainfall, drought, and pumping.

The imaginary level to which water in a confined aquifer would rise under its own pressure. It indicates the hydraulic head and where flowing wells may occur.

A well drilled into a confined aquifer where water rises above the top of the aquifer. If pressure is sufficient, water flows at the surface without pumping.

A measure of how easily water moves through a geologic material. Higher values mean water flows more readily, supporting greater well yields.

The ability of a material to transmit fluids through its connected pore spaces. It influences how quickly groundwater recharges a well and how contaminants may spread.

The process by which water from rain, streams, or irrigation enters an aquifer. Recharge sustains groundwater levels and affects long-term well productivity.

The cone-shaped lowering of the water table or potentiometric surface around a pumping well. It forms because water is removed faster than it can flow in.

A group of bacteria used as an indicator of drinking water sanitary quality. Their presence in well water suggests possible contamination and requires investigation.

Bacteria associated with the intestines of warm-blooded animals, used to detect sewage or animal waste contamination. Their presence in a well is a serious health concern.

The physical, chemical, and biological characteristics of water that determine its suitability for drinking and other uses. Wells must be protected from contamination to maintain acceptable quality.

A nitrogen compound often linked to fertilizer, manure, or septic contamination. High nitrate in well water is a health concern, especially for infants.

A watertight seal at the top of a well casing that keeps surface water, insects, and debris out. It is a key barrier protecting groundwater quality.

A cover fitted over the top of a well casing to exclude rain, debris, and animals while allowing access for service. It works with the sanitary seal to protect the well.

Written authorization required before drilling or modifying a water well in Alabama. It identifies the well location, owner, and intended use and is issued through the state regulatory program.

A record filed after a well is finished that documents its location, depth, casing, grouting, and yield. Regulators use it to track wells and protect groundwater.

The Alabama Department of Environmental Management, the state agency responsible for environmental programs including water well regulation and groundwater protection.

A well no longer in use that must be properly sealed to prevent contamination and safety hazards. Sealing requirements are set by state regulation and typically require grout or bentonite.