AZ Water Operator flashcards
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32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Hydrologic cycle
- The continuous movement of water through evaporation, transpiration, condensation, precipitation, runoff, and infiltration, replenishing surface and groundwater sources.
- Watershed
- The land area that drains to a common water body; protecting it from contamination is a key strategy for source water protection.
- Safe yield
- The maximum withdrawal rate from a water source that can be sustained without depleting the source or causing adverse environmental or legal effects.
- TMDL
- Total Maximum Daily Load: the maximum pollutant amount a water body can receive and still meet water quality standards, including point and nonpoint sources and a margin of safety.
- Coagulation
- The process of destabilizing colloidal particles by adding chemicals (e.g., alum) that neutralize negative surface charges, allowing particles to aggregate.
- Flocculation
- Gentle mixing that promotes collisions and agglomeration of destabilized particles into larger floc, typically lasting 30–60 minutes.
- Sedimentation
- Gravity settling of floc and suspended solids in a clarifier; typical overflow rates are 0.5–1.0 gpm/ft² and detention time is 2–4 hours.
- CT
- Disinfectant concentration multiplied by contact time; used to determine pathogen inactivation credit, with requirements varying by disinfectant, pH, and temperature.
- Feed rate formula
- Chemical feed rate in lb/day = dose (mg/L) × flow (MGD) × 8.34 lb/gal; used to calculate the mass of chemical needed per day.
- Secondary containment
- A structure (e.g., curb, dike) around chemical storage that holds at least 110% of the largest container's volume to contain spills.
- Sodium hypochlorite storage
- Liquid bleach degrades with heat and sunlight; store in a cool, dark, ventilated area and use within its shelf life to maintain strength.
- SDS
- Safety Data Sheet: a document providing hazard, handling, and emergency information for a chemical, required by hazard communication regulations.
- Cavitation
- Formation and collapse of vapor bubbles in a pump when NPSHA is less than NPSHR, causing noise, vibration, and damage.
- Affinity laws
- For centrifugal pumps, flow varies directly with speed, head with the square of speed, and power with the cube of speed.
- Brake horsepower
- bhp = (flow in gpm × head in ft × specific gravity) / (3960 × pump efficiency); represents the power required by the pump.
- Check valve
- A valve that allows flow in one direction only, preventing backflow and protecting pumps and piping from reverse flow.
- Air gap
- The only absolute backflow prevention method; a physical separation between the potable water supply and a nonpotable source, at least twice the pipe diameter and never less than 1 inch.
- RPZ assembly
- Reduced pressure zone backflow preventer; must be tested annually by a certified tester and provides protection against both backpressure and backsiphonage.
- Backsiphonage
- Backflow caused by negative pressure in the supply line, which can draw nonpotable liquids into the potable water system.
- Main flushing
- Opening hydrants or blowoffs to create scouring velocity (at least 2.5–3.0 ft/s) to remove sediment and biofilm from water mains.
- Total coliform MCL
- No more than 5% of monthly samples may be positive for total coliform for systems collecting at least 40 samples per month; any positive requires repeat sampling.
- Turbidity
- A measure of water clarity in nephelometric turbidity units (NTU); filtered water must be ≤0.3 NTU in 95% of monthly samples and never exceed 1 NTU.
- DPD method
- A colorimetric method using DPD reagent to measure free and total chlorine residual in water samples.
- Sodium thiosulfate
- A chemical added to bacteriological sample bottles to neutralize chlorine, preventing it from killing bacteria during transport.
- SDWA
- Safe Drinking Water Act: federal law authorizing the EPA to set national drinking water standards; states may obtain primacy to enforce them.
- Consumer Confidence Report
- An annual report delivered to customers by July 1 that describes source water, detected contaminants, and compliance with drinking water regulations.
- Lead action level
- 0.015 mg/L for lead in tap water; compliance is based on the 90th percentile of samples, triggering corrosion control and public education.
- TTHM MCL
- 0.080 mg/L for total trihalomethanes, a group of disinfection byproducts regulated under the Stage 2 Disinfectants/Disinfection Byproducts Rule.
- Confined space entry
- Entry into a space with limited access and potential atmospheric hazards; requires a permit, atmospheric testing, ventilation, attendant, and rescue plan.
- LOTO
- Lockout/tagout: a procedure to isolate hazardous energy sources during maintenance, using locks and tags applied only by authorized employees.
- Chlorine gas leak
- Evacuate upwind, use SCBA, and never enter a chlorine atmosphere without proper PPE; chlorine gas is heavier than air and highly toxic.
- SCADA security
- Protecting supervisory control and data acquisition systems from cyber threats through firewalls, access controls, and network segmentation.