AL Water Operator flashcards

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

Public water system definition

A system providing water for human consumption through pipes to at least 15 service connections or regularly serving at least 25 people for at least 60 days per year.

Turbidity and pathogen risk

Turbidity measures suspended particles that scatter light; high turbidity can shield pathogens from disinfection and increase chlorine demand, making it a key treatment indicator.

Nitrate MCL

The federal maximum contaminant level for nitrate is 10 mg/L measured as nitrogen; higher levels can cause methemoglobinemia, especially in infants under six months.

Arsenic MCL

The federal MCL for arsenic is 0.010 mg/L, or 10 µg/L; long-term exposure above this level increases the risk of skin, bladder, and lung cancer.

Groundwater under direct influence

Groundwater that is hydraulically connected to surface water and can be contaminated by it; it is generally treated and monitored as surface water under the Safe Drinking Water Act.

Reservoir turnover

Seasonal mixing of a stratified lake or reservoir when surface water cools and sinks, often bringing low-oxygen water with elevated iron, manganese, and taste-and-odor compounds to intakes.

Coagulation purpose

Coagulation adds chemicals to neutralize the negative surface charge on particles, allowing them to collide and stick together instead of repelling each other.

Alum and alkalinity

Aluminum sulfate reacts with natural alkalinity to form floc; if alkalinity is too low, pH drops and coagulation fails, so lime or soda ash may be added.

Jar test

A bench-scale test using multiple beakers with different coagulant doses and pH values to identify the best chemical dose and mixing conditions for plant treatment.

Flocculation

Gentle, slow mixing after coagulation that encourages small particles to collide and grow into larger, settleable floc; typical detention is about 15 to 45 minutes.

Surface overflow rate

Sedimentation design parameter equal to flow divided by tank surface area, usually expressed in gpm/ft²; lower rates provide more settling time and better particle removal.

Rapid sand filter rate

Conventional rapid sand filtration commonly operates at about 2 to 4 gpm/ft²; higher rates increase particle breakthrough risk and require careful turbidity monitoring.

Filter turbidity limits

For conventional filtration, combined filter effluent must be 0.3 NTU or less in at least 95 percent of monthly measurements, and no individual filter may exceed 1.0 NTU.

CT concept

CT is disinfectant concentration in mg/L multiplied by contact time in minutes; required CT depends on the disinfectant, target pathogen, pH, and temperature.

Chlorine demand

Chlorine demand is the difference between the chlorine dose applied and the residual remaining after a specified contact time; it reflects reactions with organics, ammonia, iron, and manganese.

Breakpoint chlorination

Adding chlorine past the point where ammonia and other demand are satisfied produces free chlorine residual; the breakpoint is roughly 7.6 pounds of chlorine per pound of ammonia nitrogen.

Free versus combined chlorine

Free chlorine is uncombined hypochlorous acid or hypochlorite and is a stronger disinfectant; combined chlorine, or chloramine, is weaker but more persistent and forms fewer disinfection byproducts.

Chlorine MRDL

The maximum residual disinfectant level for chlorine and chloramine is 4.0 mg/L as Cl2, measured in the distribution system; it is a health-based maximum, not a target.

UV disinfection

Ultraviolet light inactivates pathogens by damaging nucleic acids; credit depends on validated dose in mJ/cm², and UV leaves no persistent residual in the distribution system.

Total dynamic head

TDH is the total head a pump must overcome: static elevation difference plus friction and minor losses plus velocity head, expressed in feet of water.

Water horsepower formula

Water horsepower equals gallons per minute times head in feet divided by 3960; brake horsepower is water horsepower divided by pump efficiency.

Affinity laws

For a centrifugal pump at constant impeller diameter, flow varies with speed, head varies with speed squared, and power varies with speed cubed.

Cavitation cause

Cavitation occurs when local pressure drops below vapor pressure, forming vapor bubbles that collapse and damage the impeller; it is prevented by keeping NPSH available above NPSH required.

Minimum distribution pressure

Distribution systems are commonly required to maintain at least 20 psi under normal operating conditions to prevent backflow and contamination; fire flow may require higher pressures.

Air gap backflow protection

An air gap is a physical separation between the potable water outlet and the flood level of a receiving vessel; it provides the highest level of backflow protection.

Storage tank turnover

Poor turnover in storage tanks increases water age, reduces chlorine residual, and can promote nitrification or bacterial growth; tanks should be operated to cycle water.

Alabama primacy agency

The Alabama Department of Environmental Management administers the federal Safe Drinking Water Act in Alabama and enforces public water system regulations in Alabama Administrative Code Chapter 335-7.

TTHM MCL

The federal maximum contaminant level for total trihalomethanes is 80 µg/L, calculated as a locational running annual average at each monitoring location.

E. coli positive response

A positive E. coli result in a distribution sample is an acute risk; the system must notify the primacy agency promptly, issue Tier 1 public notice, and complete corrective actions.

CCR deadline

Community water systems must deliver a Consumer Confidence Report to customers by July 1 each year, covering monitoring results from the previous calendar year.

Confined space entry

Entry requires a permit, atmospheric testing for oxygen, flammables, hydrogen sulfide, and carbon monoxide, plus ventilation, an attendant, and retrieval equipment.

Pounds per day formula

Pounds per day of chemical equals concentration in mg/L times 8.34 times flow in million gallons per day; rearrange to find dose when pounds per day and flow are known.