CT Well Driller flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Cable-tool drilling method

A drilling method that breaks rock by repeatedly dropping a heavy chisel bit on the hole bottom; cuttings are removed with a bailer and casing is driven as the hole advances.

Mud rotary circulation

A rotary drilling method that circulates bentonite or polymer fluid down the drill pipe and up the annulus to cool the bit, lift cuttings, and stabilize the borehole wall with a filter cake.

Lost circulation

The loss of drilling fluid into a permeable or fractured formation, causing reduced returns at the surface; treated by lowering pump rate, adding lost-circulation material, or setting casing past the loss zone.

Well development purpose

The process of removing drilling fines and wall cake from the formation around a well so that the aquifer transmits water freely and the well produces clear, sediment-free water.

Annular space minimum

Connecticut requires at least 6 inches of space between the borehole wall and the outside of the casing, and at least 2 inches between casing and any inner liner, to allow grout placement.

Tremie grouting procedure

Grout is pumped through a pipe lowered to the bottom of the annular space and displaced upward, filling the space from bottom to top without voids or bridging.

Neat cement grout mix

Cement grout mixed with no more than 6 gallons of clean water per 94-pound sack of cement, providing a hard, durable annular seal around the well casing.

Sanitary well cap

A vermin-proof, watertight cap fitted over the top of the casing, which extends at least 12 inches above grade, to prevent surface water and contaminants from entering the well.

Pitless adapter

A fitting installed through the casing below the frost line that carries water to the building while maintaining a watertight, sanitary seal and allowing the drop pipe to be removed.

Darcy's law

The relation Q = K i A, stating that groundwater discharge equals hydraulic conductivity times hydraulic gradient times cross-sectional area for laminar flow through porous media.

Specific yield

The fraction of total rock or sediment volume that drains by gravity when the water table drops; it is the drainable porosity and controls the usable storage of an unconfined aquifer.

Transmissivity

The product of hydraulic conductivity and saturated thickness (T = K b); it describes the rate at which an aquifer transmits water through its full saturated thickness under a unit gradient.

Fractured bedrock aquifer

A groundwater system in crystalline rock such as Connecticut schist and gneiss where water occurs mainly in fractures and faults; well yield depends on intersecting fracture zones rather than rock porosity.

Cone of depression

The drawdown shape around a pumping well, deepest at the well and rising outward; it deepens with higher pumping rate and lower transmissivity and can interfere with nearby wells.

Potentiometric surface

The level to which water would rise in a well completed in a confined aquifer, representing the pressure head; artesian flow occurs where this surface lies above land surface.

Total dynamic head

The total head a pump must overcome: static lift plus drawdown plus friction loss in the discharge pipe plus the pressure head required at the point of use.

Pump operating point

The flow and head at which a pump's performance curve intersects the system curve; the pump operates most efficiently and reliably near this point.

Pressure tank precharge

The air pressure in a bladder tank, set about 2 psi below the pump cut-in pressure so the tank stores water properly and limits pump cycling.

Specific capacity

The well yield divided by drawdown, expressed in gallons per minute per foot of drawdown; a higher value indicates a more productive well or aquifer.

Drawdown

The difference between the static water level and the pumping water level in a well during pumping, measured in feet and used to compute specific capacity.

Well drilling contractor registration

A required state registration with the Connecticut Department of Consumer Protection that a well drilling contractor must hold, along with licensed individual drillers, to legally drill wells.

Well permit requirement

Before drilling a new well or substantially altering an existing one, a permit or registration must be filed with the local health department, which approves location and construction.

Well setback from septic tank

Connecticut requires a well to be at least 25 feet from a septic tank and 50 feet from a leaching field or subsurface sewage disposal area to protect the water supply.

Well completion report

A required report filed with the state and local health department documenting well depth, casing, grout, yield, and water quality, with a copy provided to the well owner.

Abandoned well sealing

An unused well must be filled with approved grout or material and sealed, then reported to the state, because an unsealed well is a direct pathway for surface contamination to groundwater.

Call Before You Dig

The 811 service that locates underground utilities before excavation or drilling; striking a gas, electric, or fuel line can be fatal.

Confined space entry

Entry into a well pit or vault requires atmospheric testing for oxygen, hydrogen sulfide, and combustible gas, plus a permit, an attendant, and a retrieval system; never enter alone.

Silica dust control

Air rotary drilling generates silica-containing dust; use water spray or dust suppression and respiratory protection, and monitor noise around compressors and rigs.

Spill containment

Fuel, oil, and drilling fluids must be stored with containment and absorbent materials, and any release must be reported to the state to protect groundwater.

Lockout/tagout

A safety procedure that isolates and de-energizes pump and control circuits before servicing, preventing accidental startup; ground-fault protection and proper grounding are also required.

Grout seal environmental role

The annular grout seal, sanitary cap, and proper abandonment prevent surface contamination from traveling down the casing and directly entering groundwater.

Rigging load safety

Keep personnel clear of the rotary table and suspended loads, inspect cables and slings, and never exceed the rig's rated capacity during hoisting operations.