ME Water Operator flashcards

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

CT value

Product of disinfectant residual concentration in mg/L and effective contact time in minutes. Regulatory tables convert CT into log inactivation credit based on temperature, pH, and disinfectant.

Breakpoint chlorination

The chlorine dose at which free chlorine residual begins to rise after destroying ammonia and chloramines. Requires roughly 7.6 mg Cl2 per mg of ammonia nitrogen.

Jar test

Bench-scale simulation of coagulation, flocculation, and settling used to select chemical dose and pH. Rapid mix, slow flocculation, settle, then measure turbidity.

Turbidity limit

Conventional filtration must produce 0.3 NTU or less in 95% of monthly samples and never exceed 1 NTU. Slow sand and DE filters use a 1 NTU limit.

Chlorine demand

Difference between the chlorine dose applied and the residual remaining after a specified contact time. It reflects oxidizable matter and ammonia in the water.

Filter backwash expansion

Backwash rate must fluidize the bed enough to release captured solids, typically 20–25% bed expansion for anthracite and sand dual media.

TTHM MCL

Maximum contaminant level for total trihalomethanes is 0.080 mg/L, evaluated as a locational running annual average at each monitoring site.

Enhanced coagulation

Treatment technique that increases coagulant dose or lowers pH to remove natural organic matter, reducing disinfection byproduct precursors before chlorine is applied.

Minimum distribution pressure

Distribution systems must maintain at least 20 psi at all points under normal and emergency conditions, including main breaks and fire flow events.

Hazen-Williams equation

Empirical head loss formula: h = 10.44 × L × Q^1.85 / (C^1.85 × d^4.87) in US customary units, where C is the pipe roughness coefficient.

Water hammer

Pressure surge caused by rapid velocity change when a valve closes or a pump stops. Surge pressure rise is approximately 0.07 psi per ft/s of velocity change.

Air gap

Physical separation between a potable water outlet and the flood level of a receiving vessel. It is the only backflow prevention method that is completely reliable.

RPZ assembly

Reduced-pressure zone backflow preventer required for high-hazard cross connections. It uses two check valves and a relief valve that discharges if differential pressure is lost.

Distribution flushing velocity

Scouring velocity of at least 2.5 to 3.0 ft/s is needed to lift and carry sediment out of mains during unidirectional flushing programs.

Main repair disinfection

After repair, apply 50–100 mg/L chlorine for at least 30 minutes, flush the main, then collect coliform and chlorine residual samples before restoring service.

Storage components

Distribution storage is sized for equalization, fire flow, and emergency reserve. These are separate design components and are not interchangeable in sizing calculations.

Total coliform 5% rule

Systems collecting 40 or more routine samples per month may have no more than 5% total-coliform-positive samples. Any E. coli positive is an acute violation.

Ground Water Rule

Requires 4-log virus inactivation or removal for groundwater systems with a significant deficiency or fecal indicator contamination, or a state-approved alternative.

Consumer Confidence Report

Annual report of detected contaminants and monitoring results delivered to customers by July 1, covering the previous calendar year of sampling.

Lead action level

Lead action level is 0.015 mg/L at the 90th percentile. Exceedance triggers corrosion control evaluation, source water treatment, and public education.

Copper action level

Copper action level is 1.3 mg/L at the 90th percentile. Exceedance requires corrosion control treatment evaluation and public education within set deadlines.

Arsenic MCL

Maximum contaminant level for arsenic is 0.010 mg/L. Treatment options include coagulation with iron, ion exchange, and adsorption media.

Nitrate MCL

Maximum contaminant level for nitrate is 10 mg/L as nitrogen, equivalent to 45 mg/L as nitrate. It protects against methemoglobinemia in infants.

Public notification tiers

Tier 1 acute violations require notice within 24 hours, Tier 2 within 30 days, and Tier 3 within one year through the Consumer Confidence Report.

Wellhead protection area

Land surface around a well through which contaminants could reach the well. Delineation supports source water inventory and contaminant management.

Confined space atmosphere

Entry requires oxygen between 19.5 and 23.5%, LEL below 10%, hydrogen sulfide below 10 ppm, and carbon monoxide below 35 ppm before and during entry.

Chlorine gas behavior

Chlorine gas is about 2.5 times heavier than air and collects in low areas. Escape or entry requires SCBA, not an air-purifying respirator.

Lockout tagout

Energy isolation procedure under 29 CFR 1910.147. Only the worker who applied the lock and tag may remove them after verifying zero energy.

Hypochlorite storage

Sodium hypochlorite degrades faster in heat and releases oxygen gas. Store in vented, shaded tanks away from acids to prevent chlorine gas release.

Boil-water notice

Public advisory to boil water for at least one minute before drinking. Rescinded only after two consecutive negative coliform samples and agency approval.

GFCI protection

Ground-fault circuit interrupter protection is required for portable electrical tools used in wet or damp areas such as treatment basins and pump rooms.

Emergency response plan

Documented procedures for contamination, pressure loss, power failure, and main breaks. It should be exercised with tabletop drills at least annually.