MD Well Driller flashcards
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31 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Static water level
- The level of water in a well when the pump has been off long enough for the water level to stabilize. It is measured from a reference point at the top of the casing.
- Pumping water level
- The water level in a well while the pump is operating at a constant rate after drawdown has stabilized. It is used with static level to compute drawdown.
- Drawdown
- The difference between the static water level and the pumping water level, measured in feet. It increases with pumping rate and reflects the cone of depression around the well.
- Specific capacity
- The pumping rate divided by drawdown, expressed in gallons per minute per foot. It measures well efficiency and declines as pumping rate increases.
- Grout minimum thickness
- The annular space must be grouted with a minimum thickness of 1.5 inches for boreholes up to 10 inches in diameter and 2 inches for larger boreholes.
- Sanitary well seal
- A watertight cap at the top of the casing that excludes surface water and insects. It must include a screened vent turned downward and openings for the pump and drop pipe.
- Pitless adapter
- A fitting that carries the discharge line through the casing below the frost line, allowing the pump to be removed without a pit. It must seal the casing watertight.
- Casing material standards
- Well casing must be new steel meeting ASTM A53 or A589, or NSF/ANSI 14 PVC, with minimum steel wall thickness of 0.188 inch and PVC of SDR 21 or heavier.
- Setback from septic system
- A well must be at least 50 feet from a septic tank or absorption field and 100 feet from a sewage lagoon or manure storage to protect the water supply from contamination.
- Rotary air drilling
- A drilling method that uses compressed air to cool the bit and lift cuttings. It works well in hard rock but needs foam or water where the formation caves.
- Mud rotary drilling
- A method that circulates bentonite or polymer drilling fluid to cool the bit, remove cuttings, and hold back formation fluids. Mud weight is monitored to prevent blowout.
- Cable tool drilling
- A percussion method using a heavy bit and bailer to break and remove rock. It is suited to unconsolidated sand and gravel and produces a clean borehole.
- Hollow-stem auger
- A flight auger with a hollow center and removable plug that allows drilling below the water table and installation of casing or sampling tools through the stem.
- Down-the-hole hammer
- A pneumatic hammer located at the bottom of the drill string that delivers high-frequency impacts to hard rock. Penetration depends on air volume and bit pressure.
- Reverse circulation drilling
- A method that pumps drilling fluid down the annulus and up the drill pipe, carrying cuttings upward inside the pipe. It allows large-diameter holes and continuous samples.
- Tricone roller bit
- A rotary bit with three rotating cones fitted with hardened teeth or inserts. It is used for soft to medium formations and is common in mud rotary drilling.
- Annular velocity
- The upward speed of drilling fluid in the space between the drill pipe and borehole wall. It must exceed the settling velocity of cuttings to prevent them from accumulating.
- Well development
- The process of removing drilling fluid and fine particles from the formation around the screen using surging, jetting, air-lifting, or overpumping to improve yield.
- Development completion criteria
- Development is complete when the discharge runs clear, sand content falls below 5 parts per million, and specific capacity has stabilized.
- Constant-rate pump test
- A test that pumps a well at a steady rate for at least two hours while recording water levels. It determines yield, drawdown, and specific capacity.
- Step-drawdown test
- A test that pumps a well at successively higher rates to separate formation loss from well loss. It is used to estimate well efficiency and the well-loss coefficient.
- Chlorine disinfection dose
- A new or repaired well must be disinfected with at least 50 milligrams per liter of chlorine and held for a contact time of at least 12 hours before use.
- Chlorine demand
- The amount of chlorine consumed by the formation, casing, and organic matter before a free residual remains. The dose must be checked during contact time.
- Bacteriological sample handling
- Samples are collected in sterile containers, chilled during transport, and analyzed within 30 hours of collection for total coliform and E. coli.
- Pumping to waste after disinfection
- After the contact time, the well is pumped to waste until the chlorine residual is gone and the water runs clear, before a bacteriological sample is collected.
- MDE well permit
- A permit from the local health department, under Maryland Department of the Environment rules in COMAR 26.04.04, must be obtained before drilling a new well.
- Well completion report
- A report filed with the Maryland Department of the Environment within 30 days of completion that records location, depth, casing, grout, yield, and static water level.
- Notice of intent to drill
- A notice filed with the Maryland Department of the Environment at least 3 business days before drilling begins, except emergency repairs, which require notice within 24 hours.
- State Board of Well Drillers
- The Maryland board that issues well driller licenses and may suspend or revoke a license for gross negligence, falsified reports, or improper well abandonment.
- Well abandonment
- A process that removes or perforates the casing, fills the borehole with grout or approved material, and files a report with the Maryland Department of the Environment.
- License renewal requirements
- A Maryland well driller license must be renewed with continuing education credit hours approved by the State Board of Well Drillers, along with required insurance and bond.