MN Well Driller key terms

The pipe installed in a borehole to keep the hole open and prevent soil or rock from caving in, and to seal off unwanted water or contamination before the well screen or intake is set.

The gap between the outside of the well casing and the wall of the drilled borehole, which must be filled with grout or sealing material to prevent surface water and shallow groundwater from moving down the well.

A cement-based or bentonite-based slurry placed in the annular space to form a low-permeability barrier that stops water and contaminants from traveling vertically along the outside of the casing.

A mixture of Portland cement and water with no sand or aggregate, commonly used to seal the annular space because it sets hard and bonds tightly to both the borehole wall and the casing.

A clay composed mostly of montmorillonite that swells when wet, used as a drilling mud, as a grout component, or as a plugging material because of its low permeability when hydrated.

A slotted or perforated section of pipe installed at the producing zone of a well that lets water enter while holding back sand and gravel from the surrounding aquifer material.

Sorted gravel placed in the annular space around a well screen to filter out fine aquifer particles and improve the flow of water into the well while stabilizing the formation.

The watertight connection at the top of the well, such as a grouted or gasketed well cap, that keeps surface water, insects, and debris from entering the well between the casing and the pump piping.

A cover fitted over the top of the casing that is designed to be watertight and vermin-proof while allowing access for measuring water levels or servicing the pump and drop pipe.

A fitting that lets the discharge pipe pass through the well casing below the frost line so the water line can be buried without a pit, keeping surface water from entering the well.

The level at which water stands in a well when the pump has not been running and the water table has returned to its natural, undisturbed position.

The water level in a well measured while the pump is running and drawing water, which is lower than the static level because of drawdown around the well.

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

The rate at which a well can produce water, usually expressed in gallons per minute, determined by test pumping and used to size the pump and storage system.

The well yield divided by the drawdown after a set pumping period, expressed in gallons per minute per foot of drawdown, used to compare how efficiently a well produces water.

A slurry of water and clay or polymers circulated during rotary drilling to cool the bit, carry cuttings to the surface, and hold the borehole wall open by hydrostatic pressure.

A drilling method in which a rotating bit cuts the rock while drilling fluid circulates down the drill pipe and back up the borehole to remove cuttings and stabilize the hole.

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

The process of removing drilling mud, fines, and loose material from the aquifer and screen after a well is constructed so the well produces clear water at its full capacity.

The permanent closure of a well that is no longer used, carried out by filling and sealing the borehole so it cannot act as a pathway for contamination between aquifers or to the surface.

Placing grout, bentonite, or other approved material in a well or borehole to block the vertical movement of water, used both during construction and when a well is abandoned.

The state program that administers Minnesota's well construction, sealing, and abandonment rules, licenses well contractors and drillers, and keeps records of water well and boring locations.

A license issued by the state that authorizes a business or individual to construct, repair, or seal wells in Minnesota, with requirements for experience, bonding, and continuing education.

The record of a well's construction that documents location, depth, geology, casing, grout, screen, and water yield, and must be filed with the state after the well is completed.

A Minnesota requirement that sellers of property with a well disclose its status to the buyer, using a certificate that identifies the well's location and whether it is in use or sealed.

The minimum required distance between a well and a contamination source such as a septic system, fuel tank, or animal feedlot, set by rule to protect the well from pollution.

A group of bacteria used as an indicator of sanitary quality in drinking water; their presence in a well sample suggests contamination from surface water, soil, or a faulty well seal.

A subgroup of coliform bacteria associated with the intestines of warm-blooded animals, whose presence in well water points to sewage or animal waste contamination and a health risk.

A nitrogen compound common in agricultural areas that can leach into groundwater from fertilizer or manure and, at high levels, causes serious illness in infants.

A naturally occurring element found in some Minnesota groundwater that is a health concern at elevated levels and is tested for when a well is constructed or when water quality is in question.

Collecting well water in a clean, approved container using proper technique, such as removing the aerator and avoiding contact with the sample, so lab results reflect the water in the well.

The documented record of who collected, handled, and transported a water sample, used to show the sample was not altered before it reached the laboratory for testing.

Equipment or processes installed to remove or reduce contaminants in well water, such as disinfection, filtration, softening, or nitrate removal, chosen based on lab test results.

Disinfecting a well by adding a strong chlorine solution, letting it stand, and then flushing the system, done to kill bacteria after construction, repair, or a positive coliform test.

A layer of clay or dense rock that slows or prevents water from moving between aquifers, protecting deeper groundwater from contamination coming from above.

A body of soil or rock that holds and transmits enough water to supply a well, such as a sand and gravel deposit or a fractured bedrock formation.

The hole drilled into the ground before casing is installed, whose diameter, depth, and stability determine how the well is constructed and sealed.

A controlled pumping period used to measure well yield and drawdown, and to confirm that the pump and water system can supply the needed flow over time.