NJ Well Driller key terms

A percussion method in which a heavy bit suspended on a wire rope is repeatedly lifted and dropped to crush rock; cuttings are removed with a bailer. Common for large-diameter residential wells in hard rock.

A rotary method using compressed air as the circulating fluid to cool the bit and lift cuttings to the surface; fast in hard rock but requires careful control of air pressure and dust suppression.

A rotary method in which a bentonite- or polymer-based drilling fluid circulates down the drill pipe and up the annulus, cooling the bit, stabilizing the borehole, and carrying cuttings to the surface.

A long steel cylinder with a flap valve used to remove cuttings and water from a borehole during cable tool drilling or to clean out a well before construction.

Steel pipe installed during drilling to hold unstable overburden open, then withdrawn before the permanent well casing and screen are set; its removal must not collapse the formation.

The final steel or plastic pipe left in the well to support the borehole, isolate contaminated zones, and provide a conduit for the pump and water.

A slotted or perforated section of pipe installed opposite the producing aquifer that allows water to enter while holding back formation material; slot size is matched to the grain size of the aquifer.

Sorted gravel or coarse sand placed in the annulus around a well screen to filter formation particles, increase the effective radius of the well, and improve yield.

Engineered granular material of a specified size range placed between the screen and the formation so that fine particles pass through while coarser material is retained; designed to prevent sand production.

Cement, bentonite, or other approved material placed in the annular space between the casing and borehole wall to prevent surface water and shallow groundwater from moving along the casing.

A watertight seal at the top of the well, often a concrete or bentonite pad and a sealed well cap, that keeps surface water, insects, and debris out of the well.

The gap between the outside of the well casing and the wall of the borehole, which must be filled with grout or filter material to protect the well.

The process of removing drilling mud, silt, and fine formation particles from the screen and surrounding aquifer so the well produces clear water at its maximum practical yield.

A close-fitting tool lowered on a cable and moved up and down to force water alternately in and out of the screen, breaking down mud cake and loosening fines.

A development technique in which compressed air is introduced through an eductor pipe to lift water and fines from the well, drawing groundwater through the screen at high velocity.

Restoring a well's yield or water quality by mechanical, chemical, or hydraulic treatment after biological fouling, mineral encrustation, or sand plugging has reduced performance.

Deposits of iron, manganese, or calcium carbonate minerals that build up on well screens and pump parts, reducing open area and lowering yield over time.

Plugging of a well by iron-related bacteria and their slime and mineral deposits, often producing reddish water, odors, and declining specific capacity.

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

The level at which water stands in a well when no pumping is occurring and the water table or potentiometric surface has stabilized.

The water level in a well while it is being pumped at a steady rate, after drawdown has stabilized; used with static level to compute drawdown.

Well yield in gallons per minute divided by drawdown in feet; a measure of well efficiency and a baseline for judging whether rehabilitation has restored performance.

A water-bearing layer bounded above and below by low-permeability material, so water is under pressure and rises in a well to a potentiometric surface above the top of the aquifer.

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

A well completed in a confined aquifer in which the potentiometric surface stands above the top of the aquifer, so water rises above the aquifer without pumping.

A well in which the natural pressure in the aquifer is sufficient to raise water above land surface without a pump; requires a control valve and sealed casing.

A multistage centrifugal pump and motor assembly installed below the pumping water level, pushing water to the surface; sized to the well yield and total dynamic head.

The total equivalent height the pump must overcome, equal to the vertical lift plus drawdown plus discharge pressure head plus friction losses in piping and fittings.

The depth at which the pump intake is placed, deep enough to stay submerged at maximum drawdown but above the screen or bottom of the well.

A vessel with a captive air charge that stores water under pressure, allowing the pump to cycle less often and maintaining household pressure between pump cut-in and cut-out settings.

A one-way valve installed in the pump discharge line to prevent backflow that would let water drain from the drop pipe and cause the pump to restart or spin backward.

Movement of fine formation material into a well, causing abrasive damage to pumps and filling of the well; usually addressed with a filter pack, screen resizing, or rehabilitation.

A group of indicator organisms whose presence in well water signals possible contamination from surface water, septic systems, or an improperly sealed well.

Treatment of a well with a chlorine solution after construction, repair, or a positive bacteria test, followed by flushing until residual chlorine is gone before sampling.

Permanently sealing a well that is no longer used by filling it with approved grout and capping it, so it cannot convey contamination between aquifers or act as a hazard.

A mixture of Portland cement and water, sometimes with additives, used to seal annular spaces and abandon wells because it sets hard and bonds to casing and formation.

A clay-based sealing mixture, often blended with cement or sand, that swells on contact with water and is used where a flexible, low-permeability seal is needed.

Written authorization from the state or local agency required before drilling, deepening, or altering a well, specifying construction and location conditions that must be met.

The minimum required horizontal distance between a well and a contamination source such as a septic system, fuel tank, or property line, set by regulation to protect water quality.

The driller's log documenting depth, casing, screen, grout, formations, water levels, and yield for a completed well, filed with the regulatory agency and retained by the driller.

A work area such as a pit or vault with limited entry and exit that is not designed for continuous occupancy and may contain hazardous atmospheres, requiring testing and attendant procedures.

A safety procedure that isolates electrical or mechanical energy sources and applies locks and tags so equipment cannot be started while workers service it.