IL Water/WW Operator flashcards

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

Groundwater under direct influence

Groundwater hydraulically connected to surface water and subject to its contamination. It must receive treatment equivalent to surface water, meaning filtration plus disinfection, once the state makes that determination.

Rising headloss across a bar screen

A growing water-level difference across a bar screen means debris is plugging the openings. Operators rake or mechanically clean the screen to protect downstream pumps, grit chambers, and channels.

Presedimentation basin function

A presedimentation basin holds raw water long enough for heavy grit, sand, and coarse solids to settle before coagulation, reducing pump wear, clarifier loading, and swings in coagulant demand.

Jar test purpose

A jar test simulates rapid mix, flocculation, and settling at several coagulant doses so the operator can select the dose and pH that give the best settled and filtered turbidity.

Alkalinity consumed by alum

Each 1 mg/L of alum dosed consumes roughly 0.45 mg/L of alkalinity as calcium carbonate and releases carbon dioxide, lowering pH. Too little alkalinity prevents complete hydrolysis and poor floc results.

Parshall flume flow measurement

A Parshall flume measures flow in an open channel using the depth of water at a fixed upstream point. Flow is obtained from a table or formula based on throat width and head.

CT value in disinfection

CT is the disinfectant residual concentration in mg/L multiplied by effective contact time T10 in minutes. The required CT depends on the disinfectant, pH, temperature, and target log inactivation.

Filter backwash bed expansion

Rapid sand filters are backwashed at roughly 15 to 20 gpm/ft2, which expands the bed about 20 to 30 percent. Too little expansion leaves media dirty; too much washes media to waste.

Langelier Saturation Index meaning

The Langelier Saturation Index compares measured pH with the pH at calcium carbonate saturation. A positive index means scale-forming water; a negative index means corrosive water that can leach lead and copper.

Chloramine chlorine to nitrogen ratio

Monochloramine forms most readily near a 5-to-1 weight ratio of chlorine to ammonia nitrogen. Higher chlorine doses oxidize the ammonia and, past breakpoint, leave a free chlorine residual.

Rapid mix velocity gradient

Rapid mix disperses coagulant at a velocity gradient of roughly 300 to 1000 per second for less than 30 seconds, so hydrolysis products contact particles before flocculation begins.

Clarifier overflow rate

Overflow rate equals flow divided by clarifier surface area, usually expressed in gpm/ft2. It sets the settling velocity a particle must exceed to be removed in that basin.

Optimal fluoride concentration

The Public Health Service recommends about 0.7 mg/L fluoride in drinking water to prevent tooth decay while limiting dental fluorosis, with state rules setting reporting and control requirements.

Hazen-Williams head loss

Friction loss equals 10.44 times length times flow to the 1.852 power, divided by the C factor to the 1.852 power times diameter to the 4.87 power, using feet and cubic feet per second.

Main flushing scour velocity

Flushing removes sediment only when velocity reaches about 2.5 ft/s or more, with many utilities targeting 5 ft/s. Lower velocities stir deposits without carrying them out of the main.

Air gap backflow protection

An air gap is the physical separation between a potable water outlet and the flood-level rim of a receiving vessel. It gives the highest protection against backflow and needs no mechanical testing.

Water hammer cause

Water hammer is a pressure surge caused by a rapid change in flow velocity, such as fast valve closure or a pump trip. Surge pressure travels through the pipe at the wave speed.

Minimum distribution system pressure

At least 20 psi must be maintained at all points in the distribution system under normal and emergency conditions, because lower or negative pressure allows contamination to enter through leaks and cross connections.

Storage tank turnover

Tanks should cycle their stored volume often enough to keep a disinfectant residual and prevent stagnation, which otherwise causes residual loss, byproduct formation, and nitrification in chloraminated systems.

DPD chlorine test

The DPD colorimetric method reacts free chlorine with the indicator to form a magenta color read on a photometer. Adding potassium iodide measures total chlorine, so combined chlorine is total minus free.

BOD5 incubation conditions

Biochemical oxygen demand is measured by incubating a seeded sample at 20 degrees Celsius in the dark for five days and reporting the dissolved oxygen consumed in milligrams per liter.

Total suspended solids drying temperature

Total suspended solids are captured on a glass fiber filter and dried at 103 to 105 degrees Celsius to constant weight. The weight gained divided by sample volume gives mg/L.

Coliform membrane filter pore size

Coliform membrane filtration uses a 0.45 micrometer filter that retains bacteria while water passes through, after which the filter is placed on selective medium and incubated for colonies.

Lead and copper sample collection

First-draw samples are collected from a tap that has stood unused for at least six hours, using a one-liter bottle, to measure lead and copper released from household plumbing.

Turbidity measurement unit

Turbidity is reported in nephelometric turbidity units, or NTU, measured as the light scattered at 90 degrees from suspended particles in a calibrated nephelometer.

Chlorine residual sample holding time

Free and total chlorine residuals change rapidly after collection, so the test must be run at the sample site immediately, generally within about 15 minutes of drawing the sample.

Tier 1 public notice

Tier 1 notices cover violations with immediate health risk, such as an E. coli MCL or nitrate exceedance, and must reach the public within 24 hours through media and posted notice.

Nitrate maximum contaminant level

The nitrate MCL is 10 mg/L measured as nitrogen and the nitrite MCL is 1 mg/L, because higher levels cause methemoglobinemia, especially in infants under six months old.

Consumer Confidence Report deadline

Community water systems must deliver or post their annual Consumer Confidence Report, covering source water, detected contaminants, and compliance, by July 1 for the prior calendar year.

Confined space oxygen range

Entry requires oxygen between 19.5 and 23.5 percent, flammable gas below 10 percent of the lower explosive limit, and hydrogen sulfide below the exposure limit before anyone enters.

Illinois drinking water primacy agency

The Illinois Environmental Protection Agency holds primacy to enforce the federal Safe Drinking Water Act in Illinois, issuing permits, monitoring schedules, and violations, and certifying water system operators.

TTHM running annual average limit

Total trihalomethanes must not exceed a locational running annual average of 80 micrograms per liter under the Stage 2 Disinfectants and Disinfection Byproducts Rule.