MS Water Operator flashcards

33 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 (mg/L) and contact time (minutes) used to determine disinfection credit; required CT increases with higher pH, lower temperature, and higher turbidity.

Jar test purpose

Bench-scale test that determines optimal coagulant dose and pH by simulating coagulation, flocculation, and settling; results guide full-scale chemical feed adjustments.

Combined filter effluent turbidity

For conventional filtration, must be 0.3 NTU or less in at least 95 percent of monthly measurements and never exceed 1 NTU; individual filter action level is 1.0 NTU.

Alkalinity consumption by alum

Each mg/L of alum dosed consumes about 0.45 mg/L of alkalinity; insufficient alkalinity drops pH and reduces coagulation effectiveness, requiring lime or caustic addition.

DPD method

Colorimetric test for free and total chlorine residual; reagent reacts with chlorine to produce a pink color measured against a standard, with total chlorine measured after adding iodide.

Filter backwash triggers

Backwash is initiated by headloss limit, turbidity breakthrough, or maximum run time; backwash rate should expand the media bed roughly 20 to 30 percent.

Fluoride MCL and secondary standard

Primary MCL for fluoride is 4.0 mg/L; secondary standard is 2.0 mg/L; optimal concentration is temperature-dependent, roughly 0.7 to 1.2 mg/L.

Minimum distribution pressure

Pressure must not fall below 20 psi at any point in the distribution system under normal or emergency conditions, including main breaks and fire flow.

Hydrant flow formula

Q equals 29.83 times C times d squared times the square root of pitot pressure, where d is nozzle diameter in inches and C is the discharge coefficient.

New main disinfection

Chlorinate new mains to 25 mg/L for 24 hours or 50 mg/L for 24 hours, flush, then obtain two consecutive negative bacteriological samples 24 hours apart.

Air gap backflow protection

Physical separation between the potable water outlet and the flood-level rim of the receiving vessel; provides the highest degree of backflow protection against backpressure and backsiphonage.

Dead-end flushing velocity

Flushing should achieve velocities above about 2.5 feet per second to scour biofilm and sediment from dead-end mains; frequency is set by residual and bacteriological history.

Storage tank turnover

Tank volume divided by average daily demand gives detention time; excessive detention degrades chlorine residual and increases disinfection byproduct formation.

Pressure test for new mains

Test at 1.5 times working pressure or 150 psi, whichever is greater, held at least 2 hours; allowable leakage follows the AWWA formula based on pipe length and diameter.

Reduced-pressure zone assembly

Backflow preventer with two check valves and a relief valve that protects against both backpressure and backsiphonage; requires annual testing by a certified tester.

GWUDI determination

Groundwater under the direct influence of surface water is determined by site-specific hydrogeologic and microbial investigation; such sources must meet surface water treatment rules.

Well specific capacity

Pumping rate divided by drawdown, expressed in gallons per minute per foot; declining specific capacity indicates clogging of the well screen or aquifer.

Darcy's law

Groundwater flow equals hydraulic conductivity times hydraulic gradient times cross-sectional area; describes flow through porous media under laminar conditions.

Drawdown definition

Difference between the static water level measured before pumping and the pumping water level measured during pumping; used to calculate specific capacity and well yield.

Confined versus unconfined aquifer

Confined aquifers are bounded by low-permeability layers and hold water under pressure; unconfined aquifers have a water table open to the atmosphere.

Wellhead protection area

Land surface around a well where contaminants could reach the well; delineated by time-of-travel zones, commonly one-year and five-year zones.

Source water assessment

Inventory of potential contaminant sources, susceptibility analysis, and public availability of results; states use it to support source water protection planning.

Total coliform repeat sampling

Each routine total coliform-positive sample requires repeat samples within 24 hours; a single positive routine sample triggers three repeat samples at that site.

E. coli public notice

An E. coli-positive repeat sample requires Tier 1 public notice within 24 hours; the system must also complete additional repeat sampling and corrective actions.

TTHM and HAA5 MCLs

Stage 2 DBPR locational running annual average MCLs are 80 micrograms per liter for total trihalomethanes and 60 micrograms per liter for five haloacetic acids.

Lead and copper action levels

Action level is 0.015 mg/L for lead and 1.3 mg/L for copper at the 90th percentile; exceedance triggers corrosion control treatment and public education.

Consumer Confidence Report deadline

Annual report must be delivered to customers by July 1 covering the prior calendar year, including source water, detected contaminants, and required health effects language.

Public notice tiers

Tier 1 notices within 24 hours for acute health risk; Tier 2 within 30 days; Tier 3 within one year, which the annual Consumer Confidence Report can satisfy.

Confined space atmospheric limits

Entry requires oxygen between 19.5 and 23.5 percent, combustible gas below 10 percent LEL, hydrogen sulfide below 10 ppm, and carbon monoxide below 35 ppm.

Lockout tagout steps

Isolate all energy sources, apply locks and tags by each worker, release stored energy, and verify zero energy before beginning work; only the applying worker removes the lock.

Trench protection threshold

Excavations 5 feet deep or greater require sloping, shoring, or a trench box; spoil piles at least 2 feet from the edge and ladders within 25 feet of workers.

Tier 1 public notice deadline

Notice within 24 hours for acute health risks such as E. coli or nitrate exceedance; must use methods that reach all customers and be documented.

Risk-based asset prioritization

Priority equals probability of failure times consequence of failure; used to sequence repair, rehabilitation, and replacement of distribution and treatment assets.