Water Distribution Operator Class II flashcards
Water Distribution Operator Class II · Build recall with a focused review session.
32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Safe yield
- The maximum rate at which water can be withdrawn from a source without causing long-term depletion or unacceptable environmental impact.
- Watershed
- The land area that drains all precipitation to a common outlet, such as a stream, lake, or groundwater recharge area.
- Peaking factor
- The ratio of maximum demand (day or hour) to average demand, used to size pipes, pumps, and storage.
- GWUDI
- Groundwater under the direct influence of surface water; requires treatment equivalent to surface water, including filtration and disinfection.
- Gate valve
- A valve used for isolation, not throttling; it should be fully open or fully closed to prevent seat damage.
- Thrust block
- A concrete block placed at bends, tees, and dead ends to resist the thrust force created by internal water pressure.
- Air release valve
- A valve installed at high points of a pipeline to automatically vent trapped air that can restrict flow and cause pressure surges.
- Corporation stop
- A valve installed at the water main to connect and control flow to an individual service line.
- Affinity laws
- For a centrifugal pump, flow varies directly with speed, head with the square of speed, and power with the cube of speed.
- Cavitation
- Formation and collapse of vapor bubbles in a pump due to insufficient NPSHA, causing noise, vibration, and impeller damage.
- NPSH
- Net positive suction head; NPSHA must exceed NPSHR to prevent cavitation. NPSHA is the absolute pressure available at the pump suction.
- Best efficiency point
- The flow rate at which a pump operates most efficiently, with minimal vibration and energy use; shown on the pump curve.
- Pressure and elevation
- Pressure in psi equals elevation in feet multiplied by 0.433; conversely, 1 psi equals 2.31 feet of water column.
- Water hammer
- A pressure surge caused by a sudden change in flow velocity, often from rapid valve closure, which can damage pipes and fittings.
- Altitude valve
- A valve that controls the filling of a storage tank by closing when the tank reaches a set maximum water level.
- Tank turnover
- The time required to replace the volume of water in a storage tank; typically 2–5 days to prevent stagnation and maintain water quality.
- CT value
- The product of disinfectant concentration (C) and contact time (T), used to determine the effectiveness of disinfection for pathogen inactivation.
- Breakpoint chlorination
- The point at which chlorine demand is satisfied and further chlorine addition produces free chlorine residual.
- Coliform sample
- A 100 mL water sample collected in a sterile bottle with sodium thiosulfate, analyzed for total coliform and E. coli bacteria.
- Trihalomethanes
- Disinfection byproducts formed when chlorine reacts with organic matter; regulated maximum contaminant level is 80 µg/L for TTHM.
- Backsiphonage
- Backflow caused by negative pressure in the supply line, which can draw non-potable water into the potable system.
- Air gap
- A physical separation between a potable water outlet and a flood rim, providing the highest level of backflow protection.
- RPZ assembly
- Reduced pressure zone backflow preventer; a testable assembly used for high-hazard protection that includes two check valves and a relief valve.
- Double check valve
- A backflow prevention assembly with two check valves, used for low-hazard protection against both backpressure and backsiphonage.
- Main disinfection
- New water mains are filled with chlorinated water (25–50 mg/L) for 24 hours, flushed, and sampled for bacteria before being placed in service.
- Pressure test
- A test of a newly installed or repaired pipeline at 1.5 times the working pressure for at least 1.5 hours to check for leaks.
- Tapping saddle
- A clamp placed around a water main to provide a sealed connection for a service line or branch without shutting down the main.
- Valve exercising
- The periodic operation of valves to ensure they are functional and can be closed during emergencies; typically done annually.
- Confined space
- A space with limited entry and exit, not designed for continuous occupancy, requiring atmospheric testing and a permit for entry.
- Trench protective system
- A method such as sloping, shoring, or a trench box used to protect workers from cave-ins in trenches 5 feet or deeper.
- Consumer Confidence Report
- An annual water quality report that community water systems must provide to customers by July 1, detailing contaminants and health effects.
- SDWA
- The Safe Drinking Water Act, the federal law that authorizes EPA to set national drinking water standards and oversee implementation by states.