MI Well Driller key terms

The depth below ground surface at which water stands in a well when the pump has been off long enough for the water level to stop rising. It is measured from a fixed reference point on the casing.

The depth to water measured while the pump is running at a steady rate, after the cone of depression has stabilized. Comparing it with static level gives drawdown for the pumping rate used.

The distance water level drops in a well because of pumping, equal to pumping water level minus static water level. It grows with pumping rate and reflects how easily the aquifer releases water to the borehole.

The roughly cone-shaped depression in the water table or potentiometric surface that forms around a pumping well. Its shape shows how far the pumping stress reaches into the aquifer and whether nearby wells may interfere.

A geologic formation that holds and transmits enough groundwater to supply a well at a usable rate. Sand and gravel deposits and fractured or porous bedrock are common examples in Michigan.

A low-permeability bed such as clay or dense till that restricts water movement between aquifers. It separates shallow and deep flow systems and influences where grout seals and casing depths are needed.

A well that taps a confined aquifer whose water level rises above the top of the aquifer, and sometimes above ground, without pumping. The shut-in pressure reflects the elevation of the recharge area.

The mixture of sand, gravel, silt, clay, and boulders deposited by glaciers across Michigan. Its grain size and sorting control how much water a well can produce and how much casing and screening it needs.

A well completed in consolidated rock rather than unconsolidated deposits. Yield depends on intersecting fractures or solution openings, so production can vary sharply between nearby locations.

A controlled pumping or bailing test that measures how much water a well produces and how far the water level drops. Results guide pump sizing, screen selection, and the report of yield to the owner.

Well yield divided by drawdown, usually expressed in gallons per minute per foot of drawdown. A higher value means the aquifer and well construction deliver water with less water-level decline.

The pipe installed in a borehole to keep the hole open and prevent loose material or shallow water from entering. It must be sized, joined, and set to meet depth and sealing requirements.

A slotted or perforated section installed at the producing zone to hold back formation material while letting water enter the well. Slot size is matched to the grain size of the aquifer.

Sorted gravel placed in the annulus around a screen to filter formation sand and improve flow into the well. Its grain size is selected relative to the aquifer material and the screen slot size.

The grout or other approved material placed in the space between the borehole wall and the casing. It blocks surface water, shallow groundwater, and contaminants from moving down along the outside of the casing.

A cement-based or bentonite-based mixture pumped into the annulus to form a low-permeability seal. Placement method and volume must be controlled so the seal fills the space without voids or bridging.

A mixture of portland cement and water, sometimes with approved additives, used to seal the annulus. It sets hard, bonds to casing and formation, and is a standard high-quality sealing material.

A small-diameter pipe used to place grout at the bottom of the annulus so the material rises from below. This method displaces water upward and reduces voids compared with pouring from the surface.

A vermin-proof, tightly fitting cap that seals the top of the casing and includes a vent and a wiring opening. It prevents surface water, insects, and small animals from entering the well.

The process of removing drilling mud, fines, and disturbed material from around the screen so the well produces clear water at its full capacity. Methods include surging, jetting, bailing, and air lifting.

A development or test method that injects air into the water column so the rising air-water mixture lifts water and debris from the well. It can clear fines but must be controlled to avoid damage.

A close-fitting tool moved up and down in the casing to force water in and out through the screen. The repeated reversals loosen and flush fine material from the gravel pack and formation.

The depth at which a submersible pump is placed, chosen to stay submerged during pumping while leaving room for drawdown and seasonal water-level changes. It must remain above the screen and any seal.

A one-way valve at the bottom of a suction line or pump intake that keeps water in the pipe when the pump stops. It prevents loss of prime and keeps debris from backflowing into the line.

A valve that allows flow in one direction only, used in pump discharge lines to stop water from running back into the well. It protects the pump and keeps the pressure system charged.

A tank with a trapped air charge that stores water under pressure so the pump does not cycle on and off with every small draw. Correct precharge and tank size extend pump life.

A device that starts and stops the pump at set low and high pressure points. Proper settings and clean contacts keep the water system operating within its design pressure range.

A group of bacteria used as an indicator of sanitary quality in drinking water. Their presence in a well sample suggests a pathway for surface contamination or a problem with disinfection or well construction.

A subset of coliform bacteria associated with warm-blooded animal waste. Detection signals a likely sewage or manure source and a serious health concern requiring investigation and corrective action.

A soluble form of nitrogen that moves easily through soil into groundwater, often from fertilizer, manure, or septic systems. Elevated levels in well water are a health concern, especially for infants.

A naturally occurring element found in some Michigan groundwater, particularly in certain bedrock and drift settings. It is tested because long-term exposure above the drinking water limit poses health risks.

A measured portion of well water collected in a clean, appropriate container for laboratory analysis. Correct technique, timing, and handling are essential so results reflect actual well conditions.

The documented record of who collected, handled, transported, and received a water sample. It preserves sample integrity and supports the reliability of laboratory results if questions arise.

The permanent closure of a well that is no longer used, by cleaning, filling, and sealing it so it cannot act as a pathway for contamination. Proper abandonment protects the groundwater resource.

Placing approved sealing material in a well to block vertical water movement and prevent contamination migration. The method depends on well depth, diameter, and the geology it penetrates.

A well where natural pressure raises water above ground level without pumping. It requires a controlled outlet and sealing so water does not run uncontrolled and cause waste or damage.

The cover on top of a well casing that keeps out water, debris, and animals and supports the pump wiring. It must be secure and vented as required for the well type.

The reduction in yield or increase in drawdown in one well caused by pumping of another nearby well. It is assessed by comparing water levels and pumping rates before and during nearby pumping.

A regulatory limit or guideline for a contaminant in drinking water. Well contractors use these values to decide whether a sample result requires treatment, retesting, or notification of the owner.

A pump that uses a venturi nozzle and a recirculating stream of water to lift water from a well. It is common in shallow or small-yield wells and depends on a foot valve to stay primed.