ABC Class II Water Treatment cheat sheet

Turbidity is measured in NTU and indicates suspended particles; higher turbidity increases disinfectant demand and can shield pathogens.

TOC indicates organic precursor content; elevated TOC raises disinfection byproduct formation potential after chlorination.

Alkalinity buffers pH; water with low alkalinity, often below 50 mg/L as CaCO3, is more sensitive to coagulant acidification.

Hardness as CaCO3 reflects calcium and magnesium; high hardness promotes scaling and affects coagulation chemistry.

Surface water is vulnerable to Cryptosporidium and Giardia; groundwater under direct influence of surface water requires surface-water-type treatment.

A sanitary survey identifies contamination risks in the watershed, wellhead area, treatment plant, storage, and distribution system.

Source water pH, temperature, and conductivity affect treatment; temperature changes alter coagulation and disinfection efficiency.

Watershed protection uses land-use controls, spill response, and wellhead protection; preventing contamination is preferred over treating it later.

A jar test determines coagulant dose and pH by comparing settleability and filtered turbidity across several doses.

Coagulation destabilizes particles by charge neutralization; flocculation gently mixes water so destabilized particles grow into settleable flocs.

Rapid mix velocity gradient is typically 300 to 1000 s^-1 for seconds; flocculation velocity gradient is typically 10 to 75 s^-1 for minutes.

Optimum coagulant dose often occurs near charge neutralization; overdosing can restabilize particles and increase residual turbidity.

Alkalinity consumes alum or ferric coagulant; insufficient alkalinity depresses pH and may require alkalinity addition.

Stokes law settling velocity increases with particle diameter squared and density difference and decreases with water viscosity.

Surface overflow rate equals flow divided by basin surface area; particles with settling velocity greater than this rate are ideally removed.

Sedimentation performance improves with stable floc, low short-circuiting, and proper sludge removal; excessive weir loading increases solids carryover.

Filter media effective size and uniformity coefficient describe gradation; uniformity coefficient equals d60 divided by d10.

Conventional filtration loading rates are often 2 to 6 gpm/ft2; higher rates increase the risk of particle breakthrough.

Backwash expands media and removes captured solids; adequate expansion and duration help prevent mudballs and media loss.

Filter headloss increases as media capture particles; terminal headloss triggers backwash before breakthrough occurs.

Turbidity breakthrough is passage of particles into filtered water before terminal headloss and is indicated by rising effluent turbidity.

Filter ripening is the initial period of higher effluent turbidity after backwash; filter-to-waste or slow starts reduce it.

The L/d ratio relates media depth to grain size; deeper beds provide more contact time and solids capacity.

Support gravel prevents media loss and distributes backwash water; upset gravel can allow media into the underdrain.

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

Free chlorine is more effective at lower pH because hypochlorous acid dominates; the pKa is about 7.5 at 25 C.

Chlorine demand is the difference between applied dose and residual after contact; demand must be satisfied before a persistent residual remains.

Chloramination provides a longer-lasting residual but is a weaker primary disinfectant; it can form nitrite, nitrate, and nitrosamines.

UV disinfection inactivates Cryptosporidium but provides no residual; a secondary disinfectant is needed in distribution.

Ozone is a strong disinfectant and oxidant; it can produce bromate and requires off-gas ozone destruction.

Disinfection byproduct formation increases with TOC, chlorine dose, contact time, pH, and temperature; monitor TTHM and HAA5.

Booster chlorination maintains residual in distribution; residual must be monitored at representative distribution points.

Dechlorination with reducing agents may be needed before discharging chlorinated water; confirm residual before release.

Chemical feed rate in lb/day equals flow in MGD multiplied by dose in mg/L multiplied by 8.34.

Solution feed rate equals chemical mass dose divided by solution strength; verify units before setting a feed pump.

Calibrate chemical feed pumps by measuring delivered volume over time; a drawdown test verifies actual feed rate.

Sodium hypochlorite degrades with heat, light, and age; store it cool, dark, ventilated, and rotate stock.

Never mix chlorine with ammonia or acids; such reactions can release toxic gas or heat.

Secondary containment for liquid chemicals should hold at least the volume of the largest container.

Chemical storage areas require ventilation, eyewash access, PPE, and SDS access; incompatible chemicals must be separated.

Day tanks should be labeled with chemical name and concentration; feed lines should be dedicated to prevent cross-connections.

A pump curve plots head versus flow; the operating point is the intersection of the pump curve and system curve.

Cavitation occurs when NPSH available is less than NPSH required; it causes noise, vibration, and impeller damage.

Affinity laws: flow varies with speed, head with speed squared, and power with speed cubed at constant impeller diameter.

Gate valves isolate flow, globe valves regulate flow, check valves prevent backflow, and butterfly valves provide quick isolation.

Flow meters require calibration and suitable straight pipe runs; magnetic flow meters need conductive liquid.

Preventive maintenance includes lubrication, vibration checks, seal or packing inspection, and valve exercising.

Pressure gauges and level sensors must be zeroed or calibrated; inaccurate instruments mislead process control.

Lockout/tagout isolates energy before maintenance; verify zero energy and try out the equipment before work.

Sample containers, preservation, and holding times must match the analyte; chlorine and pH are analyzed promptly on site.

Chain of custody records sample possession and transfer and preserves regulatory or legal defensibility.

Turbidity is measured by nephelometry; calibrate with formazin or approved standards and report results in NTU.

The DPD colorimetric method measures free and total chlorine; turbidity and strong oxidants can interfere.

Alkalinity titration to pH 4.5 measures total alkalinity and is reported as mg/L CaCO3.

Percent removal equals influent concentration minus effluent concentration, divided by influent concentration, times 100.

Detention time equals basin volume divided by flow rate; units must be consistent, such as gallons and gallons per minute.

Surface loading rate equals flow divided by area and is expressed as gpm/ft2 or m3/m2/d.

Log removal equals log10 of influent concentration divided by effluent concentration; 2-log removal is 99 percent and 3-log is 99.9 percent.

National Primary Drinking Water Regulations set MCLs, MRDLs, treatment techniques, and monitoring requirements.

An MCL is the maximum contaminant level allowed in drinking water; an MRDL is the maximum residual disinfectant level; both are enforceable.

Public notification Tier 1 is for acute violations and is issued within 24 hours; Tier 2 within 30 days; Tier 3 within 90 days.

The Consumer Confidence Report is delivered annually by July 1 and includes source water, detected contaminants, and health effects.

Retain monitoring records for at least five years unless a specific rule requires a longer period.

The Lead and Copper Rule uses action levels rather than MCLs; an exceedance triggers corrosion control, public education, and replacement requirements.

The Disinfection Byproduct Rule sets TTHM and HAA5 MCLs based on locational running annual averages.

The Revised Total Coliform Rule uses routine monitoring and assessment or corrective actions when exceedances occur; E. coli has an MCL.

Violations must be reported to the primacy agency; falsifying monitoring or reporting records is prohibited.

Chlorine gas is heavier than air and irritates the lungs; evacuate upwind and use supplied-air respiratory protection.

Confined space entry requires a permit, atmospheric testing for oxygen, flammables, and toxics, an attendant, and a rescue plan.

A Safety Data Sheet provides hazard, PPE, first aid, and spill information; keep SDSs accessible to workers.

Eyewash and safety shower access should be within 10 seconds travel of corrosive chemical handling areas.

Lockout/tagout and zero-energy verification are required before servicing pumps, valves, or electrical equipment.

The emergency response plan includes notification, evacuation, spill containment, and mutual aid; conduct practice drills.

Security measures include fencing, locked chemical rooms, visitor control, and awareness of chlorine theft or diversion.

Electrical safety includes GFCI protection in wet locations, clear panel access, and keeping water away from energized equipment.

Turbidity is measured in NTU and indicates suspended particles; higher turbidity increases disinfectant demand and can shield pathogens.

TOC indicates organic precursor content; elevated TOC raises disinfection byproduct formation potential after chlorination.

Alkalinity buffers pH; water with low alkalinity, often below 50 mg/L as CaCO3, is more sensitive to coagulant acidification.

Hardness as CaCO3 reflects calcium and magnesium; high hardness promotes scaling and affects coagulation chemistry.

Surface water is vulnerable to Cryptosporidium and Giardia; groundwater under direct influence of surface water requires surface-water-type treatment.

A sanitary survey identifies contamination risks in the watershed, wellhead area, treatment plant, storage, and distribution system.

Source water pH, temperature, and conductivity affect treatment; temperature changes alter coagulation and disinfection efficiency.

Watershed protection uses land-use controls, spill response, and wellhead protection; preventing contamination is preferred over treating it later.

A jar test determines coagulant dose and pH by comparing settleability and filtered turbidity across several doses.

Coagulation destabilizes particles by charge neutralization; flocculation gently mixes water so destabilized particles grow into settleable flocs.

Rapid mix velocity gradient is typically 300 to 1000 s^-1 for seconds; flocculation velocity gradient is typically 10 to 75 s^-1 for minutes.

Optimum coagulant dose often occurs near charge neutralization; overdosing can restabilize particles and increase residual turbidity.

Alkalinity consumes alum or ferric coagulant; insufficient alkalinity depresses pH and may require alkalinity addition.

Stokes law settling velocity increases with particle diameter squared and density difference and decreases with water viscosity.

Surface overflow rate equals flow divided by basin surface area; particles with settling velocity greater than this rate are ideally removed.

Sedimentation performance improves with stable floc, low short-circuiting, and proper sludge removal; excessive weir loading increases solids carryover.

Filter media effective size and uniformity coefficient describe gradation; uniformity coefficient equals d60 divided by d10.

Conventional filtration loading rates are often 2 to 6 gpm/ft2; higher rates increase the risk of particle breakthrough.

Backwash expands media and removes captured solids; adequate expansion and duration help prevent mudballs and media loss.

Filter headloss increases as media capture particles; terminal headloss triggers backwash before breakthrough occurs.

Turbidity breakthrough is passage of particles into filtered water before terminal headloss and is indicated by rising effluent turbidity.

Filter ripening is the initial period of higher effluent turbidity after backwash; filter-to-waste or slow starts reduce it.

The L/d ratio relates media depth to grain size; deeper beds provide more contact time and solids capacity.

Support gravel prevents media loss and distributes backwash water; upset gravel can allow media into the underdrain.

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

Free chlorine is more effective at lower pH because hypochlorous acid dominates; the pKa is about 7.5 at 25 C.

Chlorine demand is the difference between applied dose and residual after contact; demand must be satisfied before a persistent residual remains.

Chloramination provides a longer-lasting residual but is a weaker primary disinfectant; it can form nitrite, nitrate, and nitrosamines.

UV disinfection inactivates Cryptosporidium but provides no residual; a secondary disinfectant is needed in distribution.

Ozone is a strong disinfectant and oxidant; it can produce bromate and requires off-gas ozone destruction.

Disinfection byproduct formation increases with TOC, chlorine dose, contact time, pH, and temperature; monitor TTHM and HAA5.

Booster chlorination maintains residual in distribution; residual must be monitored at representative distribution points.

Dechlorination with reducing agents may be needed before discharging chlorinated water; confirm residual before release.

Chemical feed rate in lb/day equals flow in MGD multiplied by dose in mg/L multiplied by 8.34.

Solution feed rate equals chemical mass dose divided by solution strength; verify units before setting a feed pump.

Calibrate chemical feed pumps by measuring delivered volume over time; a drawdown test verifies actual feed rate.

Sodium hypochlorite degrades with heat, light, and age; store it cool, dark, ventilated, and rotate stock.

Never mix chlorine with ammonia or acids; such reactions can release toxic gas or heat.

Secondary containment for liquid chemicals should hold at least the volume of the largest container.

Chemical storage areas require ventilation, eyewash access, PPE, and SDS access; incompatible chemicals must be separated.

Day tanks should be labeled with chemical name and concentration; feed lines should be dedicated to prevent cross-connections.

A pump curve plots head versus flow; the operating point is the intersection of the pump curve and system curve.

Cavitation occurs when NPSH available is less than NPSH required; it causes noise, vibration, and impeller damage.

Affinity laws: flow varies with speed, head with speed squared, and power with speed cubed at constant impeller diameter.

Gate valves isolate flow, globe valves regulate flow, check valves prevent backflow, and butterfly valves provide quick isolation.

Flow meters require calibration and suitable straight pipe runs; magnetic flow meters need conductive liquid.

Preventive maintenance includes lubrication, vibration checks, seal or packing inspection, and valve exercising.

Pressure gauges and level sensors must be zeroed or calibrated; inaccurate instruments mislead process control.

Lockout/tagout isolates energy before maintenance; verify zero energy and try out the equipment before work.

Sample containers, preservation, and holding times must match the analyte; chlorine and pH are analyzed promptly on site.

Chain of custody records sample possession and transfer and preserves regulatory or legal defensibility.

Turbidity is measured by nephelometry; calibrate with formazin or approved standards and report results in NTU.

The DPD colorimetric method measures free and total chlorine; turbidity and strong oxidants can interfere.

Alkalinity titration to pH 4.5 measures total alkalinity and is reported as mg/L CaCO3.

Percent removal equals influent concentration minus effluent concentration, divided by influent concentration, times 100.

Detention time equals basin volume divided by flow rate; units must be consistent, such as gallons and gallons per minute.

Surface loading rate equals flow divided by area and is expressed as gpm/ft2 or m3/m2/d.

Log removal equals log10 of influent concentration divided by effluent concentration; 2-log removal is 99 percent and 3-log is 99.9 percent.

National Primary Drinking Water Regulations set MCLs, MRDLs, treatment techniques, and monitoring requirements.

An MCL is the maximum contaminant level allowed in drinking water; an MRDL is the maximum residual disinfectant level; both are enforceable.

Public notification Tier 1 is for acute violations and is issued within 24 hours; Tier 2 within 30 days; Tier 3 within 90 days.

The Consumer Confidence Report is delivered annually by July 1 and includes source water, detected contaminants, and health effects.

Retain monitoring records for at least five years unless a specific rule requires a longer period.

The Lead and Copper Rule uses action levels rather than MCLs; an exceedance triggers corrosion control, public education, and replacement requirements.

The Disinfection Byproduct Rule sets TTHM and HAA5 MCLs based on locational running annual averages.

The Revised Total Coliform Rule uses routine monitoring and assessment or corrective actions when exceedances occur; E. coli has an MCL.

Violations must be reported to the primacy agency; falsifying monitoring or reporting records is prohibited.

Chlorine gas is heavier than air and irritates the lungs; evacuate upwind and use supplied-air respiratory protection.

Confined space entry requires a permit, atmospheric testing for oxygen, flammables, and toxics, an attendant, and a rescue plan.

A Safety Data Sheet provides hazard, PPE, first aid, and spill information; keep SDSs accessible to workers.

Eyewash and safety shower access should be within 10 seconds travel of corrosive chemical handling areas.

Lockout/tagout and zero-energy verification are required before servicing pumps, valves, or electrical equipment.

The emergency response plan includes notification, evacuation, spill containment, and mutual aid; conduct practice drills.

Security measures include fencing, locked chemical rooms, visitor control, and awareness of chlorine theft or diversion.

Electrical safety includes GFCI protection in wet locations, clear panel access, and keeping water away from energized equipment.