Water Treatment Operator Class IV cheat sheet

Conventional surface-water train order: coagulation, flocculation, sedimentation, filtration, disinfection, and finished-water storage.

Detention time (hours) = basin volume (ft3) x 7.48 gal/ft3 / flow (gpm) / 60; verify against design criteria for each unit process.

Surface overflow rate (gpm/ft2) = flow (gpm) / clarifier surface area (ft2); rising rates shorten detention and increase solids carryover.

Filter loading rate (gpm/ft2) = flow (gpm) / filter bed area (ft2); backwash when headloss reaches the terminal value or turbidity breakthrough occurs.

Filter run terminated by either terminal headloss or effluent turbidity limit, whichever occurs first; both must be tracked.

Weir overflow rate (gpm/ft) = flow (gpm) / total weir length (ft); excessive rates cause short-circuiting and density-current problems.

Lime-soda softening removes hardness as CaCO3 and Mg(OH)2 precipitate; excess lime raises pH and requires recarbonation or acid for stabilization.

Disinfection CT (mg/L x min) = disinfectant residual (mg/L) x contact time (min); required CT rises with pH, temperature, and target log inactivation.

Turbidity regulatory benchmark for filtered water: 95% of monthly samples at or below 0.3 NTU, and no sample above 1 NTU.

Combined chlorine residual is calculated as total chlorine minus free chlorine; a rising combined fraction signals chloramine formation or nitrification.

pH is measured electrometrically with a glass electrode; calibrate with two buffers bracketing the expected range and record slope.

Alkalinity is titrated to pH 4.5 endpoint; it buffers pH and is consumed by alum or ferric coagulant addition.

Langelier Saturation Index = pH - pHs; negative values indicate corrosive water, positive values indicate scale-forming tendency.

Temperature affects disinfectant efficacy and chemical reaction rates; colder water requires higher CT for the same inactivation.

Coliform monitoring: total coliform presence triggers repeat and check samples; E. coli presence is an acute MCL violation requiring public notice.

Fluoride is dosed to an optimal target near 0.7 mg/L; the MCL is 4.0 mg/L and the secondary standard is 2.0 mg/L.

Collect bacteriological samples from designated sites in sterile bottles containing sodium thiosulfate to neutralize residual chlorine.

Maintain chlorine residual and temperature on distribution samples; record residual at time of collection for interpretation.

Preservation rules: nitric acid to pH <2 for metals, sulfuric acid to pH <2 for ammonia and nitrate, chill to 4 degrees C for most organics.

Holding times: bacteriological samples analyzed within 8 hours (30 hours if transport-limited), nitrate within 48 hours, metals within 6 months.

Use grab samples for pH, chlorine, temperature, and dissolved gases; composite samples for averaging loads across time.

Field blanks, trip blanks, and duplicates quantify contamination and precision; at least 10% QC samples per batch is typical.

Calibrate turbidimeters with primary formazin standards and verify with secondary gel standards before each sampling event.

Chain-of-custody forms must record collector, date, time, analyses requested, and every transfer of possession.

Pumps: monitor vibration, bearing temperature, seal leakage, and discharge pressure; rising vibration indicates wear or misalignment.

Chemical feed pumps require calibration by drawdown test (volume delivered over timed interval) whenever dose or rate changes.

Lubricate per manufacturer intervals; over-greasing bearings causes overheating as readily as under-lubrication.

Valves and actuators: exercise periodically to prevent seizure; record stroke time and torque trends for predictive maintenance.

Analyzers (turbidimeter, chlorine, pH) need scheduled cleaning, standard verification, and reagent replacement to avoid drift.

Maintain a critical spares inventory for seals, gaskets, impellers, and analyzer sensors based on lead time and failure history.

Filter media inspection includes bed depth, media loss, mudball formation, and gravel support disturbance during backwash.

Electrical and instrumentation work requires lockout/tagout and verification of zero energy before service.

Rising filtered-water turbidity with stable headloss suggests coagulant underfeed, filter breakthrough, or media disturbance.

Loss of chlorine residual in distribution may indicate nitrification, high demand, or sediment; check ammonia, free chlorine, and flow.

Short filter runs alternating with long runs often indicate media upset, channeling, or uneven backwash distribution.

Chlorine gas leak response: evacuate upwind, use supplied-air respiratory protection, never enter without SCBA; gas is heavier than air.

Confined-space entry requires permit, atmospheric testing (oxygen, LEL, H2S, CO), ventilation, attendant, and retrieval system.

Chemical mixing hazard: never add water to concentrated acid or caustic; add chemical slowly to water with agitation.

Jar tests diagnose coagulant dose and pH problems; compare turbidity, floc size, and settling across dose ranges.

Pump cavitation symptoms include noise, vibration, and reduced flow; check suction lift, NPSH, and clogged strainers.

Total coliform rule: no more than 5% of monthly samples positive for systems collecting 40 or more samples; any E. coli is an acute violation.

Stage 2 Disinfectants/Disinfection Byproducts Rule uses locational running annual averages for TTHM (80 ug/L) and HAA5 (60 ug/L).

Lead and copper rule action levels: 0.015 mg/L lead and 1.3 mg/L copper at the 90th percentile; corrosion control required if exceeded.

Surface Water Treatment Rule requires 99.9% (3-log) Giardia and 99.99% (4-log) virus inactivation, plus combined filter effluent turbidity limits.

Consumer Confidence Report must be delivered to customers annually by July 1 and include detected contaminants and their sources.

Public notification tiers: Tier 1 within 24 hours for acute health risks, Tier 2 within 30 days, Tier 3 within one year.

Monitoring violations and MCL exceedances require reporting to the primacy agency within the timeframe specified in the permit.

Operator certification requires continuing education hours per renewal cycle; maintain documentation of training completed.

Daily operational logs should record flows, chemical doses, residuals, turbidity, and any process changes with time and initials.

Retain bacteriological and chemical monitoring records for at least 5 years; some rule-specific records require 10 years or more.

Chain-of-custody and lab reports must be retrievable by sample date, site, and analysis for audit purposes.

Chemical usage records support dose calculations and verify that feed rates match permitted or design values.

Maintenance work orders should link to equipment tags so failure history and mean time between failures can be computed.

Standard operating procedures must be reviewed and updated after process changes or equipment replacement.

Incident and safety records: log near misses, injuries, and chemical releases with corrective actions and follow-up dates.

Shift turnover documentation should capture current process status, alarms, and pending actions to prevent information loss.