Water Treatment Operator Class IV flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Detention time formula

Detention time in hours equals basin volume in gallons divided by flow in gallons per minute, then divided by 60. Verify against design criteria for each unit process.

Surface overflow rate

Flow in gallons per minute divided by clarifier surface area in square feet. Rising rates shorten detention time and increase the risk of solids carryover.

Filter loading rate

Flow in gallons per minute divided by filter bed area in square feet. Backwash is triggered by terminal headloss or turbidity breakthrough, whichever occurs first.

CT concept

CT equals disinfectant residual in mg/L multiplied by contact time in minutes. Required CT increases with higher pH, lower temperature, and greater target log inactivation.

Lime-soda softening

Precipitation process removing calcium and magnesium hardness as carbonate and hydroxide solids. Excess lime raises pH and requires recarbonation or acid for stabilization.

Weir overflow rate

Flow in gallons per minute divided by total weir length in feet. Excessive rates cause short-circuiting and density currents in the clarifier.

Filtered water turbidity limit

At least 95 percent of monthly filtered-water samples must be at or below 0.3 NTU, and no individual sample may exceed 1 NTU.

Combined chlorine calculation

Combined chlorine equals total chlorine minus free chlorine. A rising combined fraction signals chloramine formation or distribution-system nitrification.

Langelier Saturation Index

LSI equals measured pH minus saturation pH. Negative values indicate corrosive water, positive values indicate scale-forming tendency, near zero is balanced.

Coliform MCL violation

Detection of E. coli in a distribution sample is an acute maximum contaminant level violation requiring public notice and corrective action.

Fluoride regulatory values

Optimal fluoride dose is near 0.7 mg/L. The primary MCL is 4.0 mg/L and the secondary standard is 2.0 mg/L.

Bacteriological sample bottle

Sterile bottle containing sodium thiosulfate to neutralize residual chlorine. Collect from designated sites and record chlorine residual and temperature at collection.

Sample preservation acids

Nitric acid to pH below 2 for metals; sulfuric acid to pH below 2 for ammonia and nitrate. Most organic samples are chilled to 4 degrees Celsius.

Holding time examples

Bacteriological samples analyzed within 8 hours, extended to 30 hours when transport-limited. Nitrate within 48 hours; metals within 6 months.

Grab versus composite sample

Grab samples suit pH, chlorine, temperature, and dissolved gases. Composite samples average loads across time for flow-weighted or time-weighted characterization.

Chain of custody

Form recording collector, date, time, analyses requested, and every transfer of possession. Required to demonstrate sample integrity for regulatory reporting.

Feed pump calibration

Drawdown test measuring volume delivered over a timed interval. Recalibrate whenever dose or feed rate changes or after pump maintenance.

Pump condition monitoring

Track vibration, bearing temperature, seal leakage, and discharge pressure. Rising vibration indicates wear, misalignment, or cavitation before failure.

Analyzer maintenance

Turbidimeters, chlorine analyzers, and pH meters need scheduled cleaning, standard verification, and reagent replacement to prevent measurement drift.

Filter media inspection

Check bed depth, media loss, mudball formation, and gravel support disturbance. Media problems cause short runs and turbidity breakthrough.

Lockout tagout

Electrical and instrumentation service requires energy isolation, lock and tag application, and verification of zero energy before work begins.

Short filter run causes

Alternating short and long runs suggest media upset, channeling, or uneven backwash distribution rather than a simple coagulant dose problem.

Chlorine gas leak response

Evacuate upwind and use supplied-air respiratory protection. Chlorine gas is heavier than air and accumulates in low-lying areas.

Confined space entry

Requires permit, atmospheric testing for oxygen, flammables, hydrogen sulfide, and carbon monoxide, plus ventilation, attendant, and retrieval system.

Chemical dilution rule

Never add water to concentrated acid or caustic. Add the chemical slowly to water with agitation to control heat release and splattering.

Pump cavitation symptoms

Noise, vibration, and reduced flow indicate cavitation. Check suction lift, available net positive suction head, and clogged strainers.

Total coliform rule

No more than 5 percent of monthly samples may be positive for systems collecting 40 or more samples; any E. coli is an acute violation.

Disinfection byproduct LRAA

Locational running annual averages limit total trihalomethanes to 80 micrograms per liter and five haloacetic acids to 60 micrograms per liter.

Lead and copper action levels

90th percentile action levels are 0.015 mg/L for lead and 1.3 mg/L for copper. Exceedance triggers corrosion control and public education requirements.

Surface water treatment log credits

Requires 99.9 percent (3-log) Giardia and 99.99 percent (4-log) virus inactivation, plus combined filter effluent turbidity limits.

Public notification tiers

Tier 1 within 24 hours for acute health risk, Tier 2 within 30 days, Tier 3 within one year. Consumer Confidence Report delivered annually by July 1.

Record retention periods

Bacteriological and chemical monitoring records retained at least 5 years; certain rule-specific records require 10 years or longer.