GA Well Driller key terms

A saturated geologic formation or group of formations that contains and transmits enough water to supply wells or springs in usable quantities.

A low-permeability stratum, such as clay or unfractured rock, that restricts vertical water movement and separates aquifers above and below it.

The imaginary level to which water in a confined aquifer would rise under its own pressure if not restrained, used to predict artesian flow and static levels.

The depth to water in a well measured when the pump has been off long enough for the water level to stabilize, expressed below a stated reference point.

The drop in water level in a well or aquifer caused by pumping, measured as the difference between static and pumping water levels.

The roughly conical depression in the water table or potentiometric surface that forms around a pumping well and widens as pumping continues.

Well yield in gallons per minute divided by drawdown in feet, a common indicator of how efficiently a well produces water from its aquifer.

The reduction in yield or increase in drawdown in one well caused by pumping of nearby wells whose cones of depression overlap.

A well completed in a confined aquifer in which water rises above the top of the aquifer, and may flow at the surface without pumping.

The pipe installed in a borehole to maintain the opening, prevent cave-in, and provide a conduit for water and for pump equipment.

A slotted or perforated section installed opposite a water-bearing formation that holds back formation material while allowing water to enter the well.

Graded sand or gravel placed in the annulus around a screen to stabilize the formation and reduce movement of fine particles into the well.

The gap between the borehole wall and the outside of the casing, which must be sealed to prevent unwanted water and contaminants from moving along the well.

The continuous, low-permeability material placed in the annular space to block vertical movement of water, gas, or contaminants along the outside of the casing.

A mixture of cement and water only, without sand, used to seal annular spaces because of its low permeability and good bonding to casing and formation.

A high-solids bentonite slurry used to seal annular spaces, often blended with cement, valued for swelling and low permeability in the borehole.

A pumpable cementitious or clay-based material placed to fill voids and seal annular spaces, casing seats, and abandoned boreholes against fluid movement.

A pipe used to place grout from the bottom of a space upward, keeping the discharge submerged so the grout displaces water rather than mixing with it.

The upper casing string set to seal off shallow, potentially contaminated water and unstable material, and to anchor the wellhead and subsequent casing.

A watertight connection at the wellhead, such as a grouted or gasketed well cap, that keeps surface water, insects, and debris out of the well.

The aboveground assembly at the top of a well, including the casing terminus, cap, vent, and any pump or plumbing connections.

A fitting that passes the pump discharge pipe horizontally through the casing below frost depth while keeping the casing watertight above ground.

A drilling method that turns a bit on a rotating string while circulating drilling fluid to remove cuttings and stabilize the borehole wall.

A rotary method using compressed air, often with foam, instead of liquid mud to lift cuttings, giving fast penetration in hard rock.

A percussion method that breaks rock by repeatedly lifting and dropping a heavy bit on a cable, with cuttings removed by bailing.

Mud, water, air, or foam circulated in a borehole to cool the bit, carry cuttings to the surface, and support the borehole wall.

The condition in which drilling fluid escapes into a permeable or cavernous formation instead of returning to the surface, reducing hole cleaning.

The process of removing drilling fines and mud from the formation near a well and improving the connection between the aquifer and the well.

A controlled pumping or bailing test that measures how much water a well produces and how much the water level drops.

Treatment of a well, pump, and piping with a chlorine solution after construction or repair, followed by flushing, to kill bacteria and other microorganisms.

A group of indicator organisms used in water testing; their presence suggests contamination or a defect in the well's sanitary construction.

Laboratory analysis of a well water sample for bacteria, nitrate, minerals, and other constituents to judge suitability and safety for use.

A pump and motor assembly installed below the water level in a well, pushing water to the surface through a drop pipe.

A vessel with a trapped air charge that stores pressurized water, limiting pump cycling and maintaining steady pressure in the distribution system.

A device that starts and stops the pump at preset low and high system pressures to maintain pressure in the tank and piping.

A device or arrangement that stops water from flowing backward from a use point into the well or supply, protecting the water source from contamination.

Any actual or potential link between a potable water supply and a source of contamination that could allow pollutants to enter the drinking water.

The permanent decommissioning of a well no longer in use, typically by filling and sealing it so it cannot act as a pathway for contamination.

The record filed after decommissioning a well that documents the sealing method, materials used, depths, and other details required by the regulatory agency.

The record submitted after drilling that documents well location, depth, casing, screen, grout, and water-bearing zones encountered during construction.

The minimum required horizontal distance between a well and a potential contamination source such as a septic system, animal enclosure, or fuel tank.

The process of choosing a well location by weighing aquifer potential, topography, drainage, access, and distance from contamination sources and property lines.

A written breakdown of a task into steps that identifies hazards and controls for each step before work begins on a drilling site.

Entering an enclosed or partially enclosed space with limited access that may contain hazardous air, requiring testing, ventilation, and an attendant.

Gear such as hard hats, hearing protection, gloves, and safety glasses worn to reduce injury risk during drilling and well work.