MI Well Driller flashcards
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37 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Static water level
- The water level in a well measured when the pump has been off long enough for the level to stabilize. It is the reference for calculating drawdown and pump setting depth.
- Drawdown
- The difference between the static water level and the pumping water level, expressed in feet. Drawdown increases with pumping rate and indicates the well's response to stress.
- Specific capacity
- Pumping rate in gallons per minute divided by drawdown in feet. A higher value means the well yields more water per foot of drawdown; a declining value signals plugging or aquifer decline.
- Confined aquifer
- An aquifer overlain by a low-permeability layer such as clay till or shale, which limits direct recharge from the surface. Water in it is under pressure and rises in the well.
- Outwash deposit
- Sand and gravel sorted and deposited by glacial meltwater. These deposits are typically the highest-yielding and most permeable aquifers in glaciated terrain such as Michigan.
- Test hole log
- A record of depth, soil and rock type, and water strikes made while drilling an exploratory hole. It guides casing depth, screen placement, and grout seal design.
- Annular space
- The gap between the borehole wall and the outside of the casing. It must be wide enough to place grout with a tremie and form a continuous seal.
- Well screen slot size
- The width of the screen openings, chosen from a sieve analysis of the formation so the screen retains most aquifer material while allowing fines to be developed out.
- Gravel pack
- Filter material placed in the annulus around the screen in fine or uniform formations. Its grain size is sized to the formation, and the screen slot is sized to retain the pack.
- Drive shoe
- A hardened steel ring attached to the bottom of the casing. It protects the casing edge during driving and helps form a seal as it enters firm material.
- Sanitary well cap
- A vermin-proof, tightly fitting cap on the wellhead that seals out insects and surface water while allowing the well to be vented through a screened opening.
- Pitless adapter
- A fitting that lets the discharge pipe pass through the casing below frost depth while keeping the wellhead watertight and accessible for service.
- Neat cement grout
- A mixture of cement and water only, with no more than about 6 gallons of water per 94-pound sack. It forms a strong, low-permeability seal with minimal shrinkage.
- Tremie placement
- Placing grout through a pipe that discharges below the surface of the grout already in the hole. It prevents segregation, bridging, and voids in the seal.
- Bentonite grout shrinkage
- Bentonite-based grout shrinks slightly as it cures and can crack. Where a permanent low-permeability seal is needed, cement or cement-bentonite grout is preferred.
- Grout volume formula
- Annular volume equals 0.7854 times hole diameter squared minus casing diameter squared, times the sealed height. Add 10 to 25 percent for washouts and lost circulation.
- Surface grout collar
- A mound of grout at the wellhead, typically at least 2 inches thick, that slopes away from the casing. It sheds surface water and seals the top of the annulus.
- Well development
- Removal of drilling fluid, filter cake, and fines from the formation around the screen by surging, jetting, air-lifting, or overpumping until the discharge runs clear.
- Pump submergence
- The depth of the pump intake below the pumping water level. Too little submergence causes cavitation, overheating, and premature motor failure; follow the manufacturer's minimum.
- Total dynamic head
- The total head the pump must overcome: pumping lift plus discharge pressure head plus friction losses in the drop pipe and fittings. It is used with the pump curve to select a pump.
- Check valve
- A one-way valve installed above the submersible pump that holds the water column when the pump stops, preventing backflow and backspin that can damage the pump.
- Torque arrestor
- A rubber guide fitted on the drop pipe above the pump that limits twisting and banging against the casing during pump start and stop, protecting the pipe and wiring.
- Bacteriological sample bottle
- A sterile bottle containing sodium thiosulfate to neutralize residual chlorine. It is filled to the line, leaving air space, chilled, and submitted within the holding time.
- Coliform bacteria
- A group of bacteria used as an indicator of contamination pathways in a well. Their presence means the well is vulnerable; E. coli specifically indicates fecal contamination.
- Nitrate standard
- The drinking-water limit for nitrate is 10 milligrams per liter as nitrogen. Elevated nitrate in a well often points to a failing septic system or fertilizer nearby.
- Shock chlorination
- Disinfection of a well and plumbing by adding chlorine to reach roughly 50 to 200 milligrams per liter, circulating, holding, then flushing until no chlorine remains before retesting.
- Arsenic in groundwater
- A naturally occurring contaminant in some Michigan bedrock and outwash aquifers. It has no taste or smell, so only a laboratory test confirms whether a well exceeds the standard.
- Abandonment plugging material
- Approved materials such as neat cement grout, cement-bentonite, or bentonite chips, placed from the bottom up by tremie to fill the well and seal the aquifer.
- Casing cut-off depth
- When a well is plugged, the casing is cut off below grade, commonly at least 3 feet down, and the remaining opening is filled and capped so the site drains and is safe.
- Plugging record
- Documentation filed after a well is abandoned, listing depth, diameter, materials, volumes, method, and date. It proves the well was sealed to the required standard.
- Flowing artesian well plugging
- A well that flows under its own pressure needs a grout that sets under pressure and a deep enough seal to control flow before the upper casing is cut off.
- Driller's well record
- A log completed for each well showing depth, casing, screen, grout, and water-bearing zones. Michigan requires it to be filed with the state within the set time.
- Well drilling credential
- The state-issued authorization a driller must hold to construct, alter, or plug a water well in Michigan. Working without it violates the water well statute and rules.
- Utility locate call
- A call to 811 before drilling, followed by the required waiting period, so buried gas, electric, and communication lines are marked. Never assume a clear-looking site is safe.
- Confined space entry
- Entry into a pit, vault, or large-diameter well requires air monitoring, an entry permit, a standby attendant, and retrieval equipment because of oxygen deficiency and toxic gas risk.
- Silica dust control
- Drilling and cutting rock and concrete release respirable silica. Use water or dust suppression and wear proper respiratory protection to prevent lung disease.
- Lockout tagout
- The procedure of de-energizing a circuit at the panel, locking it, and tagging it before servicing a pump or rig. Verify the circuit is dead before touching conductors.