IL Water/WW Operator cheat sheet

Coarse bar screens (openings about 1 in) and fine screens (about 1/4 in) protect downstream equipment; a rising head loss across the screen signals plugging and the unit must be raked or mechanically cleaned.

Grit removal at the headworks protects pumps, valves, and clarifiers from abrasion and solids accumulation; removed grit is normally washed before disposal.

Groundwater under the direct influence of surface water (GWUDI) must be treated as surface water: filtration plus disinfection, with a state determination based on hydrogeology and indicator organisms.

Jar tests establish the coagulant dose and coagulation pH giving the lowest settled and filtered turbidity; the optimum dose changes with raw water turbidity, alkalinity, pH, and temperature.

Alkalinity consumption is about 0.45 mg/L as CaCO3 for each 1 mg/L of alum dosed; if raw alkalinity is insufficient, lime or caustic is added to hold pH in the coagulation range.

Open-channel flow is measured with weirs or Parshall flumes; Parshall flume flow is a function of the upstream (throat) depth and the throat width, read from a table or formula.

Chlorine demand equals the applied dose minus the residual remaining after a stated contact time; it must be measured on the raw water before sizing any prechlorination dose.

Presedimentation ahead of coagulation removes heavy solids, dampens swings in raw water quality, and reduces the solids load on clarifiers and filters.

Rapid mix disperses coagulant at a velocity gradient of roughly 300-1000 s-1 for less than 30 seconds; flocculation tapers from about 100 to 10 s-1 over 15-45 minutes.

Clarifier overflow rate equals flow divided by surface area (gpm/ft2); typical design for alum floc is about 0.5-1.0 gpm/ft2, and weir loading is checked separately.

Rapid sand filters run at about 2-6 gpm/ft2; backwash at 15-20 gpm/ft2 produces roughly 20-30 percent bed expansion.

CT = C x T10, where C is residual disinfectant in mg/L and T10 is effective contact time in minutes; T10 is theoretical detention time multiplied by a baffling factor, and required CT increases as temperature falls (free chlorine) and as pH rises.

Conventional filtration must produce 0.3 NTU or less in at least 95 percent of monthly filtered-water samples and must never exceed 1 NTU.

Free chlorine and ammonia combine near a 5:1 weight ratio to form monochloramine; adding chlorine beyond the breakpoint (about 7.6:1) destroys chloramines and leaves a free chlorine residual.

Langelier Saturation Index = measured pH minus the pH at calcium carbonate saturation; positive is scale-forming, negative is corrosive, and a negative index raises lead and copper leaching risk.

Excess-lime softening raises pH to about 10.5-11 to precipitate magnesium; recarbonation with carbon dioxide lowers pH and stabilizes the water before filtration.

Recycle streams such as filter backwash and softening sludge supernatant return solids and ammonia to the head of the plant and must be accounted for in raw water quality and DBP control.

A detectable disinfectant residual must be maintained at all points; in chloraminated systems, falling total chlorine with rising nitrite indicates nitrification and requires flushing and chlorine conversion.

Flush at 2.5 ft/s or greater (many utilities target about 5 ft/s) to scour and carry sediment out; lower velocities stir deposits without removing them.

Hazen-Williams head loss: hL = 10.44 L Q^1.852 / (C^1.852 d^4.87), with hL and L in feet, Q in cfs, d in feet; the C factor decreases as pipe ages and tuberculates.

An air gap is the only backflow protection effective against both backpressure and backsiphonage; reduced-pressure-zone assemblies and testable devices require annual testing and records.

Maintain at least 20 psi at all points in the distribution system under normal and emergency conditions; low or negative pressure allows contamination intrusion through leaks and cross connections.

Water hammer is a pressure surge from rapid velocity change; surge magnitude depends on the velocity change and the pressure wave speed, and closing valves slower than the 2L/a wave travel time limits it.

Storage tanks need adequate turnover and mixing; summer stratification leaves stagnant layers with low residual and can promote nitrification or DBP formation.

Leaks are located by acoustic listening or correlation, step testing, and district metered areas; AWWA M36 water audits compare system supply with billed and unbilled consumption.

Bacteriological samples are collected in 100 mL bottles containing sodium thiosulfate, cooled to 10 degrees C or below without freezing, and analyzed within 30 hours of collection.

Total-coliform-positive samples are tested for E. coli; under the Revised Total Coliform Rule, repeat positives or E. coli findings trigger a Level 1 or Level 2 assessment rather than a coliform MCL.

Chlorine residual by DPD: free chlorine is read directly, total chlorine after adding potassium iodide, and combined chlorine equals total minus free; analyze on site within about 15 minutes.

Turbidity is measured nephelometrically in NTU with a calibrated nephelometer, using formazin or an approved primary standard and a secondary standard for daily checks.

pH meters are calibrated with at least two buffers bracketing the sample (typically 4, 7, and 10) and the slope and automatic temperature compensation are verified.

BOD5: seed if needed, incubate at 20 degrees C in the dark for five days, and report oxygen consumed; nitrification is suppressed with an inhibitor when carbonaceous BOD is required.

TSS is retained on a glass fiber filter and dried at 103-105 degrees C; VSS is the weight lost when that dried residue is ignited at 550 degrees C.

Preservation: nitrate and nitrite are chilled and acidified to pH below 2 with sulfuric acid, metals are filtered and acidified with nitric acid, and holding times follow 40 CFR 136.

Lead and copper compliance samples are one-liter first-draw samples after at least six hours of stagnation; compliance is judged by the 90th percentile against action levels of 0.015 mg/L lead and 1.3 mg/L copper.

The Illinois Environmental Protection Agency holds primacy to enforce the Safe Drinking Water Act in Illinois, issuing permits, monitoring schedules, and violations that trigger public notice.

Public notice tiers: Tier 1 within 24 hours for immediate-risk violations, Tier 2 within 30 days, and Tier 3 within one year (often in the annual report).

Key limits: nitrate 10 mg/L as N, nitrite 1 mg/L as N, arsenic 0.010 mg/L, TTHM locational running annual average 80 micrograms/L, HAA5 locational running annual average 60 micrograms/L; turbidity is a treatment technique.

Community water systems must deliver the Consumer Confidence Report to customers by July 1 each year covering the prior calendar year, and also submit it to the state.

The Groundwater Rule requires 4-log (99.99 percent) virus inactivation or removal for groundwater systems with a fecal indicator positive or an unaddressed significant deficiency.

Permit-required confined space entry: pre-test and ventilate, oxygen 19.5-23.5 percent, flammable gas below 10 percent of the lower explosive limit, hydrogen sulfide below the exposure limit, a written permit, and a trained attendant outside.

Chlorine gas leaks are detected with dilute ammonia solution forming a white cloud; cylinders are stored away from ammonia, organics, and heat, and escape respirators or SCBA are staged per the site plan.

Lockout/tagout under 29 CFR 1910.147 requires isolation of every energy source, verification of zero energy, and personal locks and tags applied by each authorized employee.

Hazard Communication requires a safety data sheet for each hazardous chemical and training on labels, hazards, and required personal protective equipment before use.