CO Well Driller key terms

The impermeable material, usually neat cement grout or bentonite, placed in the space between the borehole wall and the casing to prevent water and contaminants from moving vertically along the outside of the well.

A cement- or clay-based mixture pumped into the annular space to form a permanent barrier. Cement grout is standard in Colorado; bentonite products are used where approved, mixed to the specified density.

A grout made only of portland cement and water, with no sand or aggregate added, typically mixed at no more than about six gallons of water per 94-pound sack.

A small-diameter pipe lowered to the bottom of the annular space to place grout from the bottom upward, keeping the discharge end submerged so the seal is continuous and uncontaminated.

The drilled opening in the ground before casing and sealing are installed. Its diameter, depth, and straightness determine what casing and grout volumes the well will require.

The pipe installed in a borehole to keep the hole open and to protect the well from caving and surface contamination. Colorado rules set minimum wall thickness and require new casing in most construction.

A slotted or perforated section of casing set across a producing formation so water can enter the well while filtering out sand and gravel from the aquifer.

Filter material placed in the annulus around a well screen to hold back formation sand and improve flow into the well, sized to the aquifer material it surrounds.

The depth to the water surface in a well when the pump is off and the water has recovered to its resting level, measured from a stated reference point such as the top of casing.

The depth to water in a well while the pump is running at a steady rate, reflecting drawdown around the borehole. It is recorded on the well log along with the pumping rate.

The difference between the static water level and the pumping water level. Excessive drawdown can indicate a low-yield formation, a clogged screen, or a pump set too shallow.

The sustainable rate at which a well produces water, usually expressed in gallons per minute and estimated during a pump or bail test before the pump is sized.

The required record of a well's construction, including location, depth, casing, grout, formations encountered, water levels, and yield, filed with the state after completion.

The permanent sealing of a well or borehole no longer in use, filling it so it cannot serve as a pathway for contamination between aquifers or from the surface.

The buried piping loop, vertical or horizontal, that transfers heat between the ground and a geothermal heat pump system. In Colorado, its construction is regulated like a well.

A U-shaped high-density polyethylene pipe grouted into a drilled vertical borehole, used to exchange heat with deep ground at relatively stable temperature.

A field test that measures how readily heat moves through the ground at a proposed loop site, used to size the ground heat exchanger and estimate the required borehole length.

The sealing material placed around a ground heat exchanger pipe in its borehole. It must both seal the hole and conduct heat well, so grout selection affects system performance.

A heat-fused connection between polyethylene pipe sections in a closed-loop system. Joints must be pressure-tested because a leak would let loop fluid escape underground.

A test that pressurizes a completed loop or piping system to confirm it holds pressure without loss, verifying that joints and pipe are sound before and after grouting.

The depth at which a submersible pump is installed, chosen so the intake stays submerged during pumping while remaining above the screen or bottom of the well.

The vertical pipe that carries water from a submersible pump up to the pitless adapter or wellhead, supporting the pump and often the torque arrestor and wire.

A fitting that lets water pass through the casing wall below frost depth while keeping the well capped and sanitary, so the discharge line can be buried to the building.

A tight-fitting cover on top of the casing that keeps surface water, insects, and debris out of the well while allowing access for measurement and service.

A pump designed to operate underwater in the well, with the motor sealed and cooled by the surrounding water, pushing water up the drop pipe to the surface.

A tank with a trapped air charge that stores pressurized water so the pump does not cycle on and off with every small draw, protecting the motor and stabilizing household pressure.

A device that starts and stops the pump at preset low and high pressure settings, maintaining system pressure within a range matched to the tank's precharge.

The state authorization required before constructing, deepening, or replacing a well. In Colorado it is issued through the Division of Water Resources and carries conditions on use.

A person holding a current state license, with the required experience and examination, who is authorized to construct wells and who is responsible for the work performed under that license.

A surety instrument filed with the state to guarantee that the driller will comply with well construction rules and pay for corrective work if the driller defaults.

The bond, letter of credit, or other security a licensee must maintain so funds are available to plug an abandoned well or correct violations if the licensee fails to do so.

Required credit hours a licensee must earn each renewal cycle from approved courses, keeping knowledge of rules, construction methods, and safety current.

The periodic process of keeping a well driller license active by submitting fees, documenting required continuing education, and confirming the bond or other assurance remains in force.

Corrective work ordered or agreed to when a well was built improperly or poses a threat to groundwater, such as re-grouting, re-casing, or plugging the well.

A formal state directive requiring a licensee to correct a violation within a stated time, which may lead to further enforcement if ignored.

The minimum required horizontal distance between a well and a contamination source such as a septic system, property line, or storage tank, protecting the water supply.

A water specimen collected under proper procedures after construction and disinfection, submitted to a laboratory to document that the new well meets bacteriological and chemical standards.