CT Well Driller key terms

The process of advancing a borehole through unconsolidated material such as soil, sand, gravel, or till above bedrock, typically using casing, mud, or air to keep the hole open.

A water well in which the producing interval is a drilled hole completed in consolidated rock rather than in overburden material, common in Connecticut's crystalline and sedimentary formations.

A percussion drilling method that lifts and drops a heavy bit on a wire rope to break rock, with cuttings removed by a bailer; historically common for residential wells.

A drilling method that uses compressed air to drive a rotating bit and to lift cuttings out of the hole, often with a hammer for hard rock and foam or water for dust control.

A drilling method in which drilling fluid is circulated down the drill pipe and back up the annulus to cool the bit, stabilize the hole, and carry cuttings to the surface.

A prepared fluid of water, clay, and additives circulated during rotary drilling to control formation pressure, clean the hole, cool the bit, and build a filter cake on the borehole wall.

The condition in which drilling fluid escapes into permeable or fractured formations instead of returning to the surface, reducing hole cleaning and risking collapse or formation damage.

A rock interval containing cracks, joints, or faults that can store and transmit groundwater; in crystalline bedrock these zones usually supply most of a well's yield.

A long cylindrical tool lowered on a line to remove cuttings, sediment, or water from a borehole, and also used in some development and well-cleaning operations.

Steel or plastic pipe installed in a borehole to keep the hole open, prevent collapse, seal off unwanted water or contamination, and provide a housing for the pump and drop pipe.

Casing installed to hold back unconsolidated material while drilling or testing continues, later removed or left in place depending on the well design and regulatory requirements.

A hardened steel ring attached to the bottom of casing that cuts through soil and protects the casing end as it is driven or advanced into the formation.

A cement-based or bentonite-based mixture placed in the annular space between casing and borehole wall to seal the well against surface water, shallow groundwater, and contaminant migration.

The continuous barrier of grout or other approved material filling the space between the well casing and the borehole wall, extending to the depth required by regulation.

A grout made only of Portland cement and water, sometimes with approved additives, producing a dense seal that resists shrinkage and is commonly required for well annulus sealing.

A sealing mixture of bentonite clay and water, often blended with cement or sand, that swells to fill voids; its use and proportions must meet the applicable well construction rules.

A tight-fitting, vermin-proof cover on top of a well casing that seals the opening against insects, surface water, and debris while allowing venting and access for service.

The above-ground portion of a well, including the casing top, cap, vent, and any pitless adapter or fittings, which must be protected from flooding and contamination.

A fitting that carries the water line through the well casing below the frost line and connects to the pump piping, allowing the wellhead to be sealed without a buried pit.

A geologic formation or group of formations that stores and transmits enough groundwater to supply wells or springs, such as sand and gravel deposits or fractured bedrock.

An aquifer bounded above and below by low-permeability layers so that its water is under pressure and can rise in a well above the top of the aquifer.

The upper surface of the saturated zone in an unconfined aquifer, where pore water pressure equals atmospheric pressure and which rises and falls with recharge and pumping.

An imaginary surface representing the level to which water in a confined aquifer would rise under its own pressure if a well penetrated it.

A well that penetrates a confined aquifer and in which water rises above the top of the aquifer, sometimes flowing at the surface without pumping.

The depth to the water surface in a well when the pump has been off long enough for the water level to stabilize and reflect surrounding aquifer conditions.

The depth to the water surface in a well while the pump is running at a steady rate, after drawdown has stabilized for the test conditions.

The difference between the static water level and the pumping water level in a well, reflecting the cone of depression created by pumping.

The rate at which a well can produce water sustainably, usually expressed in gallons per minute and established through pumping tests or drilling records.

The well yield per unit of drawdown, typically gallons per minute per foot of drawdown, used to compare well performance and estimate long-term productivity.

A controlled test in which a well is pumped at a measured rate while water levels are monitored to determine yield, drawdown behavior, and aquifer characteristics.

The process of removing drilling fines and improving the connection between the well and the aquifer, often by surging, bailing, jetting, or air lifting, to increase yield and clarity.

A slotted or perforated pipe section installed opposite a water-bearing formation to hold back sediment while allowing water to enter the well.

A graded bed of clean gravel or sand placed around a well screen to filter formation material, stabilize the borehole, and improve flow into the well.

A pump with a sealed motor designed to operate underwater in a well, pushing water up a drop pipe to the surface distribution system.

The vertical pipe that carries water from a submersible pump up to the wellhead or pitless adapter, sized to limit friction loss at the design flow rate.

A tank with trapped air or a bladder that stores pressurized water so the pump does not cycle rapidly and so the system maintains steady pressure between pump cycles.

A device that starts and stops the pump at preset low and high system pressures, controlling the operating range of a pressure tank system.

A device or arrangement that stops water from flowing backward into a well or public supply, protecting the water source from contamination by chemicals or cross-connections.

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

A group of bacteria used as an indicator of sanitary quality in drinking water; their presence in a well sample signals possible contamination and requires investigation and corrective action.

Laboratory analysis of well water for indicators and contaminants such as bacteria, nitrate, arsenic, hardness, and pH, used to confirm the water is safe and suitable for use.

The proper permanent closure of an unused well by filling and sealing it with approved materials so it cannot act as a pathway for contamination or a physical hazard.

A space with limited entry and exit that is not designed for continuous occupancy, such as a well pit or vault, requiring hazard evaluation and entry precautions.

A safety procedure that isolates energy sources, such as pump or drill power, and applies locks and tags so equipment cannot be started during maintenance or repair work.

A person holding the Connecticut license required to engage in well drilling, construction, or related work, subject to the state's licensing statutes and regulations.

The approval required before drilling or constructing a well, submitted with site and proposed construction details so the work can be reviewed against state and local requirements.

The record filed after a well is finished that documents its location, depth, casing, grouting, water levels, yield, and test results as required by the state.