AK Water Operator cheat sheet

Primary drinking water standards are enforceable (MCLs, MRDLs, treatment techniques); secondary standards (SMCLs) are non-enforceable aesthetic limits.

Surface Water Treatment Rule requires 99.9% (3-log) Giardia and 99.99% (4-log) virus removal/inactivation for filtered systems; 99.9% Crypto for filtered systems under LT2.

Ground Water Rule requires 4-log virus treatment or state-approved monitoring for systems with fecally contaminated or vulnerable sources.

Turbidity limits: 0.3 NTU in 95% of monthly filtered samples and never above 1 NTU for conventional/filtration systems.

Total organic carbon (TOC) removal for conventional systems: 25% if source TOC > 2.0 mg/L, 15% if 2.0 mg/L or less, calculated as running annual average.

Nitrate MCL is 10 mg/L as N (45 mg/L as NO3); arsenic MCL is 0.010 mg/L; lead action level is 0.015 mg/L at the 90th percentile.

Alkalinity and pH govern corrosion control; Langelier Saturation Index near 0 indicates balanced water, negative is corrosive, positive is scale-forming.

Total coliform presence triggers repeat sampling; E. coli or fecal indicator presence requires Tier 1 public notice within 24 hours.

Conventional treatment sequence: coagulation, flocculation, sedimentation, filtration, disinfection.

Velocity gradient (G) in flocculation typically 10-75 s^-1 for slow flocculation and 100-300 s^-1 for rapid mix; Gt values of 10,000-100,000 optimize floc formation.

Surface overflow rate (SOR) = flow / surface area; typical sedimentation basins run 0.5-1.0 gpm/ft^2 for conventional plants.

Filtration rate = flow / filter area; rapid sand filters typically 2-6 gpm/ft^2; filter run ends on turbidity breakthrough or headloss limit (often 6-10 ft).

Backwash rate must expand media 15-25%; air scour plus water wash improves cleaning of dual-media filters.

CT (disinfection contact time) = disinfectant residual (mg/L) x contact time (minutes); required CT varies with pH, temperature, and disinfectant.

Membrane processes: microfiltration/ultrafiltration remove particles and pathogens; reverse osmosis removes dissolved ions and requires pretreatment for scaling control.

Aeration removes dissolved gases and oxidizes iron/manganese; oxidation followed by filtration is standard for iron and manganese removal.

Distribution system minimum pressure is 20 psi under normal conditions; 20 psi minimum must be maintained during main breaks and emergencies.

Maximum contaminant level for total coliform applies to distribution samples; systems collecting 40 or more samples per month may have no more than 5% total coliform-positive samples.

Chlorine residual goals: detectable free chlorine throughout the system, typically 0.2-1.0 mg/L at the extremities; state rules set minimums.

Cross-connection control hierarchy: air gap (highest protection), reduced pressure zone assembly, double check valve, vacuum breaker.

Flushing velocities of 2.5-5 ft/s scour sediment; unidirectional flushing proceeds from clean to dirty areas toward blowoff points.

Water main disinfection after repair or new installation: chlorinate to 25-50 mg/L for 24 hours or use AWWA C651 methods, then flush and test for coliforms.

Storage tank turnover prevents stagnation and disinfectant decay; tanks should be inspected and cleaned on a routine schedule.

Distribution system valves and hydrants require routine exercising; closed or partially closed valves cause pressure loss and water quality problems.

Pump head (feet) = 2.31 x pressure (psi) for water; conversely psi = feet of head / 2.31.

Brake horsepower = (flow in gpm x head in feet) / (3960 x pump efficiency); motor horsepower adds a safety factor.

Pump affinity laws: flow varies with speed, head with speed squared, power with speed cubed.

Specific speed (Ns) classifies impellers; low Ns is radial flow (high head, low flow), high Ns is axial flow (low head, high flow).

Cavitation occurs when NPSH available is less than NPSH required; symptoms include noise, vibration, and reduced flow.

Centrifugal pumps should not be run against a closed discharge valve for extended periods; energy converts to heat and can damage seals.

Motor current unbalance should be kept below 10%; voltage unbalance should be kept below 1% to avoid overheating.

Vibration analysis and thermography are predictive maintenance tools; lubrication and alignment are preventive maintenance tasks.

Chlorine gas weighs 2.5 times air; 1 pound of chlorine gas yields about 0.45 lb of free chlorine residual depending on demand.

Free chlorine exists as HOCl and OCl-; HOCl is the stronger disinfectant and dominates below pH 7.5; pKa is about 7.5.

Chlorine demand = dose applied minus residual remaining after contact time.

CT tables define required inactivation credit; higher pH and lower temperature increase required CT for free chlorine against Giardia.

Disinfection byproducts: total trihalomethanes (TTHM) MCL is 0.080 mg/L and haloacetic acids (HAA5) MCL is 0.060 mg/L, both as locational running annual averages.

Chloramination reduces regulated DBPs but requires careful nitrification control; monochloramine forms best at pH 8-9 and chlorine-to-ammonia ratio near 5:1 by weight.

Ozone and UV provide strong pathogen inactivation; UV does not leave a residual, so a secondary disinfectant is needed in distribution.

Chlorine dioxide is used for taste/odor and oxidation; its byproducts chlorite and chlorate are regulated (chlorite MCL 1.0 mg/L).

DPD colorimetric method measures free and total chlorine; total minus free approximates combined chlorine.

Turbidity is measured by nephelometry in NTU; instruments require calibration with formazin or approved standards.

pH measurement uses a glass electrode; calibrate with pH 4, 7, and 10 buffers and check slope and offset.

Jar tests determine optimal coagulant dose by simulating rapid mix, flocculation, and settling at varying doses and pH.

Total coliform presence/absence tests use enzyme substrate methods; confirmed positives require speciation and repeat sampling.

Bacteriological samples must be collected in sterile containers, kept chilled, and analyzed within holding time (typically 8 hours for chlorine residual, 30 hours for coliform).

Fluoride is dosed at 0.7 mg/L under current recommendations; MCL is 4.0 mg/L and secondary limit is 2.0 mg/L.

Process control monitoring includes filter effluent turbidity, chlorine residual, pH, alkalinity, and temperature at defined frequencies.

Public notification tiers: Tier 1 within 24 hours (immediate health risk), Tier 2 within 30 days (MCL, TT, or monitoring violations), Tier 3 within 1 year (other violations).

Consumer Confidence Report (CCR) must be delivered to customers by July 1 each year covering the prior calendar year.

Lead and Copper Rule: action levels are 0.015 mg/L lead and 1.3 mg/L copper at the 90th percentile; exceedance triggers corrosion control and public education.

Stage 2 Disinfectants and Disinfection Byproducts Rule uses locational running annual averages (LRAA) at each monitoring site.

Ground Water Rule and LT2 rule impose source water monitoring and treatment requirements; states may grant variances and exemptions under conditions.

Operators must be certified by the state; certification levels and renewal requirements vary, and operating without certification is a violation.

Sanitary surveys are required for community water systems at least every 3-5 years; significant deficiencies require correction.

Public health protection includes boil water notices when pressure drops below 20 psi or contamination is suspected.

Confined space entry requires atmospheric testing (oxygen 19.5-23.5%), ventilation, attendant, and rescue plan; permit-required spaces need entry permits.

Chlorine gas detection: use a respirator with appropriate cartridge or SCBA; evacuate upwind and notify emergency responders.

Lockout/tagout isolates hazardous energy before maintenance; verify zero energy state before work.

Hazard communication (HazCom) requires SDS access, labeling, and training for all hazardous chemicals.

Emergency response plan should address power loss, main breaks, contamination, and natural disasters; practice drills verify readiness.

Security measures include fencing, locked hatches, access control, and monitoring of treatment and storage facilities.

Chemical handling: never add water to acid; add acid to water. Store oxidizers away from reducing agents.

Electrical safety: use ground-fault protection, verify de-energized circuits, and follow NFPA 70E arc-flash boundaries.

Flow conversion: 1 MGD = 694 gpm = 1.547 cfs; 1 cfs = 448.8 gpm.

Detention time = volume / flow; keep units consistent (e.g., gallons / gpm = minutes).

Dose (mg/L) = pounds of chemical / (8.34 x million gallons of water); pounds = dose x 8.34 x MG.

Chlorine dose calculations use 8.34 lb/gal for water weight; for gas, 1 lb Cl2 = 1 lb available chlorine.

Hydraulic head loss in pipes follows Hazen-Williams: hf = 4.52 Q^1.85 / (C^1.85 d^4.87) in consistent units.

Pressure and head: 1 psi = 2.31 ft of water; 1 ft of water = 0.433 psi.

Filter loading rate (gpm/ft^2) = flow (gpm) / filter area (ft^2); weir overflow rate = flow / weir length.

Percent removal = (influent - effluent) / influent x 100; use consistent units.