CT 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.
- CT
- Disinfectant contact time value, calculated as residual concentration (mg/L) multiplied by contact time (minutes), used to determine pathogen inactivation credit.
- Log removal
- A logarithmic expression of pathogen reduction; 1-log = 90%, 2-log = 99%, 3-log = 99.9%, 4-log = 99.99% removal or inactivation.
- Surface loading rate
- Flow rate divided by clarifier surface area, expressed in gpm/ft²; typical values for sedimentation are 0.5–1.0 gpm/ft².
- Filtration rate
- Flow rate divided by filter surface area, expressed in gpm/ft²; rapid sand filters typically operate at 2–5 gpm/ft².
- Backwash
- Reverse flow through a filter to clean media; must expand bed 15–25%; rate = flow (gpm) / filter area (ft²).
- Detention time
- Theoretical time water is held in a tank or basin; volume divided by flow rate, expressed in hours or days.
- Chlorine demand
- The amount of chlorine consumed by impurities in water; calculated as dose minus residual after a specified contact time.
- Jar test
- Laboratory procedure that simulates coagulation, flocculation, and sedimentation to determine optimal coagulant dose and pH.
- LSI
- Langelier Saturation Index; indicates water's tendency to scale (positive) or corrode (negative); target near zero.
- Minimum distribution pressure
- Regulatory minimum of 20 psi throughout the distribution system under normal and fire-flow conditions to prevent contamination.
- Hazen-Williams formula
- Empirical equation for head loss in pipes: h_f = 10.44 L Q^1.85 / (C^1.85 d^4.87) in SI units, where C is roughness coefficient.
- Water hammer
- Pressure surge caused by sudden velocity change in a pipe; surge pressure = 0.07 × velocity change (ft/s) × wave speed (ft/s).
- Fire flow
- Flow rate and duration required for firefighting, typically 500–3,500 gpm for 2–4 hours, determined by local fire code.
- Storage volume
- Total capacity including equalization, fire flow, and emergency reserve; typically 1.5–2.0 times average day demand.
- Pipe velocity
- Speed of water in a pipe; typical design range 2–5 ft/s; below 1 ft/s causes sedimentation, above 10 ft/s causes excessive head loss.
- Chlorine residual
- Measurable chlorine remaining after demand is satisfied; minimum 0.2 mg/L must be maintained throughout distribution.
- Cross-connection control
- Backflow prevention using air gap (preferred) or reduced pressure zone assembly to protect potable water from contamination.
- Distribution flushing
- Controlled release of water at minimum 2.5 ft/s velocity to scour biofilm and sediment from mains.
- Turbidity
- Measure of water clarity by nephelometry in NTU; treatment technique requires ≤0.3 NTU in 95% of monthly samples for conventional filtration.
- pH
- Measure of hydrogen ion concentration; typical range 6.5–8.5; affects coagulation, disinfection efficiency, and corrosion.
- DPD method
- Colorimetric method for measuring chlorine residual; free chlorine read after 2 minutes, total after adding KI.
- Total coliform
- Bacterial indicator tested by presence/absence method; a positive result requires repeat sampling and investigation.
- HPC
- Heterotrophic plate count; pour plate method; result <500 CFU/mL indicates adequate treatment and distribution system integrity.
- Fluoride
- Measured by ion-selective electrode or colorimetric method; optimal 0.7–1.2 mg/L; MCL 4.0 mg/L.
- Nitrate
- Measured by ion chromatography or cadmium reduction; MCL 10 mg/L as nitrogen; can cause methemoglobinemia in infants.
- Lead and copper
- Action levels: Pb 0.015 mg/L, Cu 1.3 mg/L at 90th percentile; corrosion control treatment required if exceeded.
- TTHM and HAA5
- Disinfection byproducts; MCLs: TTHM 0.080 mg/L, HAA5 0.060 mg/L, based on locational running annual average.
- Total coliform rule
- Requires no more than 5% positive samples per month for systems >40 samples; any positive triggers repeat within 24 hours.
- Surface Water Treatment Rule
- Requires 99.9% (3-log) Giardia and 99.99% (4-log) virus removal/inactivation for surface water systems.
- Stage 2 DBPR
- Disinfectants/Disinfection Byproducts Rule; sets LRAA limits for TTHM and HAA5 to reduce exposure.
- Arsenic MCL
- Maximum contaminant level of 0.010 mg/L (10 ppb) for arsenic in drinking water.
- Consumer Confidence Report
- Annual report due July 1 that informs customers about source water, detected contaminants, and health effects.