SC Water/Wastewater Operator cheat sheet

Surface water includes rivers, streams, lakes, and reservoirs; groundwater includes wells and springs; source type determines treatment requirements and monitoring.

A watershed is the land area draining to a common waterbody; watershed activities such as agriculture, construction, and urbanization affect raw water sediment, nutrients, and pathogens.

Hydrologic cycle processes include precipitation, interception, infiltration, runoff, groundwater recharge, and evapotranspiration.

Baseflow is groundwater-fed streamflow during dry weather; stormflow is rapid surface runoff that raises turbidity, color, and microbial load.

Raw water quality indicators include turbidity (NTU), pH, alkalinity, hardness, color, conductivity, TDS, temperature, dissolved oxygen, nutrients, and fecal indicator bacteria.

Turbidity can shield microorganisms from disinfection and create disinfectant demand; treatment must respond to changes after rainfall and reservoir turnover.

Reservoir stratification forms an epilimnion, thermocline, and hypolimnion; turnover can bring low-oxygen water with iron, manganese, and taste-and-odor compounds into intakes.

Groundwater under the direct influence of surface water (GWUDI) requires a site-specific determination and, if confirmed, treatment and monitoring comparable to surface water.

Safe yield and low-flow statistics such as 7Q10 are used for water supply planning, withdrawal permitting, and wastewater dilution assessments.

Coagulation destabilizes colloidal particles by charge neutralization; common coagulants include alum, ferric chloride, ferric sulfate, and polyaluminum chloride, each with an optimum pH range.

Rapid mix disperses coagulant in seconds; flocculation uses gentle mixing, often measured by velocity gradient (G) and detention time, to build settleable flocs without shearing them.

Clarification removes settleable flocs; surface overflow rate, flow, and solids loading determine performance, and sludge must be removed to prevent carryover.

Rapid sand and dual-media filters remove particles by straining, interception, sedimentation, and adsorption; backwash is triggered by headloss, turbidity breakthrough, or run time.

A jar test determines coagulant dose and target pH by comparing turbidity, floc size, settling, and filtered water quality across multiple doses.

Lime-soda softening removes hardness by precipitation of calcium carbonate and magnesium hydroxide; recarbonation stabilizes the softened water and lowers pH.

Aeration strips carbon dioxide, hydrogen sulfide, and volatile organics and oxidizes iron and manganese; packed towers and diffused aeration are common.

Oxidation with chlorine, potassium permanganate, ozone, or aeration converts soluble iron and manganese to filterable particles; filtration then removes the precipitates.

Membrane processes include microfiltration, ultrafiltration, nanofiltration, and reverse osmosis; pore size and operating pressure determine which contaminants are removed.

Distribution systems must maintain positive pressure; a common regulatory minimum is 20 psi at ground level under normal conditions and during fire flow, with higher pressures avoided to limit leaks and pipe stress.

Storage tanks provide equalization, fire flow, emergency reserve, and pressure; tank turnover and water age affect residual, disinfection byproducts, and nitrification.

Pressure zones use pumps, elevated tanks, and pressure-reducing valves to keep pressures within design ranges across varying ground elevations.

Cross-connection control uses air gaps, reduced-pressure zone assemblies, double-check valves, and vacuum breakers; backflow assemblies require periodic testing.

Unidirectional flushing isolates sections and moves water one direction at target velocity to remove sediment and biofilm; dead-end flushing alone may not scour mains.

Chlorine or chloramine residual must be maintained throughout distribution; chloraminated systems require monitoring for nitrification, indicated by low ammonia, low residual, and high nitrite.

Corrosion control includes pH and alkalinity adjustment and phosphate inhibitors; lead and copper sampling at customer taps assesses corrosion control effectiveness.

Water audits compare treated volume with billed and unbilled uses; leak detection uses acoustic surveys, district metering, and nighttime flow analysis.

Valves and hydrants require exercising and flow testing; closed valves can create dead ends, pressure loss, and water quality problems.

Sanitary sewers carry domestic and industrial wastewater; storm sewers carry rainfall runoff; combined sewers carry both and can overflow during wet weather.

Gravity sewer design uses slope and diameter to maintain self-cleaning velocity, commonly about 2 ft/s minimum, while avoiding excessive velocity that causes scour and hydrogen sulfide release.

Infiltration is groundwater entering through defective pipes, joints, and manholes; inflow is stormwater entering through direct connections, and both increase treatment costs and overflows.

Lift stations use wet wells, pumps, check valves, and controls to raise wastewater; emergency storage, alarms, and standby power reduce overflow risk during power or pump failure.

Manholes require corrosion protection where hydrogen sulfide forms; drop manholes reduce turbulence and sulfide release where steep elevation changes occur.

Fats, oils, and grease cause blockages; grease interceptors and FOG programs reduce deposits and sanitary sewer overflows.

Smoke testing, dye testing, closed-circuit television inspection, and flow monitoring locate cracks, illegal connections, and infiltration sources.

Sanitary sewer overflows can contaminate surface water and groundwater; reporting, containment, cleanup, and corrective action are required.

Sewer ventilation and odor control use biofilters, chemical scrubbers, or covers to manage hydrogen sulfide and other odorous gases.

Preliminary treatment removes screenings and grit; primary sedimentation removes settleable solids and reduces the organic load on secondary treatment.

Activated sludge uses aerobic microorganisms in mixed liquor to oxidize organic matter; the clarifier separates solids, and return activated sludge maintains the biomass.

Key activated sludge controls include MLSS, MLVSS, food-to-microorganism ratio, solids retention time, dissolved oxygen, and return/waste sludge rates.

Sludge volume index (SVI) and 30-minute settling test indicate sludge settleability; high SVI suggests bulking, which can cause solids washout.

Nitrification converts ammonia to nitrate under aerobic conditions; denitrification converts nitrate to nitrogen gas under anoxic conditions using organic carbon.

Biological phosphorus removal uses anaerobic and aerobic zones; chemical phosphorus removal uses alum, ferric salts, or lime to precipitate phosphate.

Trickling filters, rotating biological contactors, and lagoons are attached-growth or natural systems; loading, temperature, and oxygen transfer affect performance.

Biosolids treatment includes thickening, digestion, dewatering, and stabilization; land application requires pathogen and vector attraction reduction.

Secondary clarifier performance depends on solids loading rate, return rate, and hydraulic loading; blanket depth and sludge age affect effluent suspended solids.

CT is disinfectant concentration (mg/L) times contact time (min); required CT depends on disinfectant, target pathogen, pH, and temperature.

Free chlorine exists as hypochlorous acid and hypochlorite; hypochlorous acid is the stronger disinfectant, and its fraction decreases as pH rises above about 7.5.

Chlorine demand is the chlorine consumed by reducing agents and organics before a residual remains; dose equals demand plus desired residual.

Breakpoint chlorination occurs when ammonia demand is satisfied; beyond breakpoint, additional chlorine produces free available residual.

Chloramines provide a persistent residual but are weaker disinfectants; chloraminated systems must control nitrification and monitor ammonia and nitrite.

UV disinfection damages microbial DNA; dose is reported in mJ/cm², and turbidity, fouling, and lamp output affect performance, with no lasting residual.

Ozone is a powerful oxidant and disinfectant but provides no residual; it can form bromate from bromide and requires off-gas destruction.

Trihalomethanes and haloacetic acids form when disinfectants react with natural organic matter; controls include precursor removal, enhanced coagulation, and distribution management.

Dechlorination uses sulfur dioxide, sodium bisulfite, or ascorbic acid; discharge permits may require dechlorination before treated water reaches receiving waters.

A pump operates where the pump curve intersects the system curve; changes in speed, impeller diameter, or system resistance move the operating point.

Affinity laws: flow varies with speed, head with speed squared, and power with speed cubed for a geometrically similar pump at constant impeller diameter.

NPSH available must exceed NPSH required; insufficient NPSH causes cavitation, noise, vibration, and impeller pitting.

Centrifugal pumps must be primed and kept free of air; positive displacement pumps require a relief valve and are not throttled on the discharge side.

Motor protection includes overload relays, fuses, circuit breakers, phase monitoring, and proper grounding; voltage imbalance and single-phasing can overheat motors.

Preventive maintenance includes lubrication, vibration analysis, thermography, seal inspection, alignment checks, and infrared testing of electrical connections.

Instrumentation commonly uses 4-20 mA signals; calibration checks zero and span against a reference, and loop wiring, grounding, and shielding affect accuracy.

Flow measurement includes magnetic, ultrasonic, vortex, Venturi, orifice, and positive displacement meters; upstream and downstream straight runs affect accuracy.

Pump troubleshooting considers suction blockage, air leaks, worn impellers, closed valves, wrong rotation, cavitation, and motor electrical faults.

A permit-required confined space has limited entry or exit, is not designed for continuous occupancy, and contains or may contain a hazardous atmosphere, engulfment, or entrapment.

Atmospheric testing order is oxygen first, then flammable gas (percent LEL), then toxic gases such as hydrogen sulfide and carbon monoxide; monitoring continues during entry.

Entry teams include an entry supervisor, entrant, attendant, and rescue service; the attendant remains outside and maintains communication.

Ventilation can remove or dilute atmospheric hazards, but testing must confirm acceptable conditions before entry and continuously during work.

Lockout/tagout isolates electrical, mechanical, hydraulic, pneumatic, and stored energy; try-start and verification confirm isolation.

Chlorine gas leaks require evacuation, notification, and use of appropriate respiratory protection; chlorine is heavier than air and irritates the respiratory tract.

Emergency action plans identify alarms, evacuation routes, communication, shutdown procedures, and external emergency contacts.

Trenching and excavation hazards include cave-in, falling loads, hazardous atmosphere, and utilities; protective systems and utility locating are required.

PPE selection follows hazard assessment and SDS information; chemical-resistant gloves, eye protection, and respiratory protection must match the exposure.

South Carolina has primacy for drinking water and wastewater programs; the Department of Environmental Services (SCDES), which absorbed SCDHEC environmental functions, issues permits and enforces regulations.

Operator certification requires the appropriate grade, passing examination, and continuing education; the operator-in-charge is responsible for compliance and reporting.

Drinking water monitoring includes total coliform, nitrate, lead and copper, disinfection byproducts, and turbidity; violations trigger public notice at required tiers.

NPDES permits set effluent limits, monitoring frequency, and reporting; discharge monitoring reports (DMRs) document compliance with permit limits.

Sanitary sewer overflows and treatment bypasses require prompt notification, cleanup, and reporting to the state agency.

The annual Consumer Confidence Report summarizes source water, detected contaminants, compliance, and health information for drinking water customers.

Unit conversions: 1 MGD = 1.547 cfs; 1 ft³ = 7.48 gal; 1 psi ≈ 2.31 ft of water; detention time = volume divided by flow.

Pounds = concentration (mg/L) × flow (MGD) × 8.34; this formula converts concentration and flow to mass loading or chemical feed.

Percent removal = [(influent − effluent) ÷ influent] × 100; use the same units for both concentrations.