CA Branch 1 cheat sheet

Safe Drinking Water Act (SDWA) authorizes EPA to set national standards; states like California may adopt stricter rules under primacy, and California's SWRCB Division of Drinking Water enforces them through Title 22 CCR.

Primary MCLs address health effects (e.g., nitrate as N 10 mg/L, arsenic 0.010 mg/L, lead action level 0.015 mg/L, total coliform treatment technique); secondary standards (250 mg/L chloride, 500 mg/L TDS, 0.3 NTU turbidity) address aesthetics and are non-enforceable federally.

Surface Water Treatment Rule requires filtered systems to achieve 0.3 NTU in 95% of monthly samples and never exceed 1 NTU, plus combined removal/inactivation of 3-log Giardia and 4-log virus.

Groundwater under the direct influence of surface water (GWUDI) must be determined by site-specific inspection or microscopic particulate analysis; GWUDI sources are regulated as surface water.

Total coliform Rule: a routine positive sample triggers repeat sampling within 24 hours; MCL violation occurs when repeat samples confirm total coliform with E. coli present or when repeat sampling is not performed.

Nitrate is the acute risk parameter for infants (methemoglobinemia); sample quarterly or annually depending on source type, and confirm any result above 5 mg/L with a second sample.

Disinfection Byproduct Rule limits: TTHM 80 ug/L and HAA5 60 ug/L as locational running annual averages at each monitoring location.

Source water assessment and wellhead protection: California requires sanitary surveys every 5 years for surface water and every 5 years for groundwater systems, documenting source vulnerabilities and required corrections.

Jar test procedure: rapid mix 1-2 minutes at 200-300 rpm, flocculate 15-20 minutes at 20-40 rpm in decreasing steps, settle 15-30 minutes, then measure turbidity and pH of supernatant.

Optimum coagulant dose is identified by the lowest settled turbidity, not by the lowest raw turbidity or shortest floc formation time; confirm with filtered turbidity where possible.

Alum (Al2(SO4)3·14H2O) consumes 0.45-0.50 mg/L alkalinity as CaCO3 per mg/L dose and depresses pH; ferric chloride consumes about 0.54 mg/L alkalinity per mg/L dose.

Coagulation pH windows: alum performs best near pH 6.0-7.5, ferric salts near pH 4-9 with optimum 5.5-6.5; outside these windows solubility increases and residual metal rises.

Zeta potential near zero indicates charge neutralization; typical target range is -5 to +5 mV, while sweep-floc operation tolerates more negative values because enmeshment dominates.

Sedimentation design: surface overflow rate = flow / surface area (m3/d per m2); typical values 20-40 m3/d·m2 for alum flocs and 40-60 m3/d·m2 with tube settlers or plate settlers.

Detention time = volume / flow; typical flocculation basins provide 15-30 minutes and sedimentation basins 2-4 hours.

Weir loading rate = flow / total weir length; keep below about 250 m3/d per m of weir to avoid floc shearing and short-circuiting.

Rapid sand filter media: effective size 0.45-0.55 mm, uniformity coefficient 1.3-1.5, bed depth 24-30 inches; anthracite dual media uses 0.9-1.1 mm effective size above sand.

Filter loading rate = flow / filter area; typical 4-8 m/h (about 2-4 gpm/ft2) for rapid gravity filters; exceeding design rate degrades effluent turbidity.

Backwash: 15-20 gpm/ft2 (35-50 m/h) with 20-30% bed expansion for 8-15 minutes; air scour at 3-5 scfm/ft2 improves cleaning in dual media.

Filter-to-waste for 15-30 minutes after backwash prevents a turbidity spike from entering the clearwell; this is a required practice in many states.

Terminal headloss triggers backwash typically at 6-10 ft (2-3 m) of water column; filter run times of 24-72 hours are typical.

Individual filter effluent must stay below 1.0 NTU; if it exceeds 1.0 NTU for two consecutive 15-minute readings, the filter is considered to have a significant deficiency requiring reporting.

Slow sand filters operate at 0.1-0.4 m/h with schmutzdecke development over 1-3 weeks; cleaning is by scraping 1-2 cm of the surface layer.

Media loss, mudballs, and air binding are common filter problems; air binding is corrected by improving backwash or increasing filter head.

CT = disinfectant residual concentration (mg/L) × contact time (minutes); required CT depends on disinfectant, pH, temperature, and target log inactivation.

Chlorine demand = applied dose - residual after contact time; free chlorine residual must be maintained at 0.2 mg/L minimum in distribution and detectable at all points.

Chlorine species distribution shifts with pH: HOCl dominates below pH 7.5, OCl- above pH 8.0; HOCl is about 80 times more effective as a disinfectant.

Chlorine decay in distribution follows first-order kinetics; k values of 0.1-0.5 per day are typical, and higher temperatures and lower pH accelerate decay.

Chloramines (NH2Cl) form when chlorine-to-ammonia ratio is about 5:1 by weight; monochloramine is a weaker but more persistent secondary disinfectant.

Ozone and UV require post-disinfection residual maintenance; UV provides no residual, so a secondary disinfectant must be applied downstream.

TTHM and HAA5 form from reactions between chlorine and natural organic matter; precursor removal by enhanced coagulation (TOC removal) is the primary control strategy.

Chlorine dioxide and ozone are strong oxidants but produce chlorite and bromate respectively; bromate MCL is 0.010 mg/L, chlorite MCL is 1.0 mg/L.

Langelier Saturation Index (LSI) = pH - pHs; LSI near 0 is balanced, negative is corrosive, positive is scale-forming; typical target is -0.5 to +0.5.

pHs = (9.3 + A + B) - (C + D), where A = (log10 TDS - 1)/10, B = -13.12 × log10(°C + 273) + 34.55, C = log10(Ca as CaCO3) - 0.4, D = log10(alkalinity as CaCO3).

Lead and Copper Rule action levels: 0.015 mg/L lead and 1.3 mg/L copper at the 90th percentile; exceedance triggers corrosion control treatment or optimization.

Optimal corrosion control for lead is typically pH adjustment to 7.5-8.5 and addition of orthophosphate (1-3 mg/L as PO4) or blended phosphate to form a protective film.

Calcium carbonate precipitation (CaCO3) forms a protective scale; deposition requires positive LSI and adequate calcium hardness (typically > 60 mg/L as CaCO3).

Aggressive water indicators: low pH (< 7.0), low alkalinity (< 50 mg/L), low hardness, high chloride-to-sulfate mass ratio (CSMR > 0.5 increases galvanic corrosion risk).

Water stability monitoring includes pH, alkalinity, calcium hardness, LSI, and corrosion coupon or pipe loop studies for large systems.

Discolored water complaints often indicate iron or manganese release from corroded mains or sediment resuspension; flushing and corrosion control adjustments are typical responses.

Pump power (kW) = (Q × H × ρ × g) / (3.6 × 10^6 × efficiency), where Q is in m3/h and H in meters; brake horsepower in US units = (gpm × ft × SG) / (3960 × efficiency).

Pump affinity laws: flow varies directly with speed, head with speed squared, and power with speed cubed; a 10% speed reduction cuts power by about 27%.

Specific speed Ns = N × √Q / H^0.75; low specific speed favors radial flow, high specific speed favors mixed or axial flow.

Best efficiency point (BEP) is where the pump operates most efficiently; operating far from BEP causes vibration, cavitation, and shortened seal or bearing life.

Net positive suction head available (NPSHA) must exceed NPSH required (NPSHR) by at least 1-2 feet to prevent cavitation; NPSHA = atmospheric pressure head + static suction head - friction loss - vapor pressure head.

Motor current imbalance greater than 10% indicates a voltage or winding problem; phase voltage imbalance should be held below 2%.

Instrumentation: 4-20 mA loops use 4 mA for zero and 20 mA for full span; a reading of 12 mA corresponds to 50% of span.

Turbidimeters must be calibrated with primary standards (formazin or AMCO AEPA-1) and verified with secondary standards; flow meters require periodic calibration checks against a master meter.

Dose (mg/L) = (chemical feed rate in lb/day × 1,000,000) / (flow in MGD × 8.34); in metric, dose = (kg/day × 1000) / (m3/day).

Feed rate (lb/day) = dose (mg/L) × flow (MGD) × 8.34; for solutions, feed rate = (solution concentration %) × (specific gravity) × (solution flow).

Detention time (hours) = (basin volume in gallons × 24) / flow in gallons per day; for rectangular basins volume = length × width × depth.

Weir overflow rate (gpd/ft) = flow (gpd) / weir length (ft); surface loading rate (gpd/ft2) = flow / surface area.

Chlorine dose calculation: (desired residual + demand) × flow × 8.34 = lb/day of chlorine; hypochlorite solution strength varies with age and must be verified by titration.

Sample handling: coliform samples require 100 mL sterile bottles, sodium thiosulfate to neutralize chlorine, iced storage, and analysis within 6 hours (8 hours for some methods); hold time for nitrate is 48 hours.

Turbidity is reported in NTU; color in color units (CU); pH measured with a calibrated electrode using pH 4, 7, and 10 buffers.

Grab samples represent a single point in time; composite samples are flow-proportioned or time-proportioned and are used for calculating averages and loading.

Chlorine gas is heavier than air and accumulates in low areas; the IDLH is 10 ppm, and the odor threshold is about 0.3 ppm; escape respirators are required when concentrations exceed 10 ppm.

Confined space entry requires atmospheric testing for oxygen (19.5-23.5%), flammables (< 10% LEL), and toxics (H2S < 10 ppm) before entry, plus a permit and attendant.

Lockout/tagout (LOTO) must isolate all energy sources before maintenance; verify zero energy state by attempting startup and testing for voltage.

Hazardous chemical storage: separate oxidizers (chlorine, permanganate) from acids and organics; secondary containment must hold 110% of the largest container volume.

Emergency response plan elements include vulnerability assessment, emergency contacts, alternate water supply, notification procedures, and annual drills.

Boil water notices are issued when pressure drops below 20 psi or when bacteriological contamination is confirmed; notices must include the reason, actions, and rescission criteria.

Security measures include fencing, locked hatches, intrusion alarms, and background checks for personnel with access to treatment chemicals.

Personal protective equipment for chemical handling includes chemical splash goggles, face shield, gloves, apron, and SCBA for chlorine gas response.

Consumer Confidence Report (CCR) must be delivered to customers by July 1 each year, covering the prior calendar year's monitoring results, violations, and source water information.

Monthly operating reports (MORs) summarize flows, chemical doses, residuals, turbidity, and compliance data; they must be submitted to the primacy agency by the 10th of the following month in California.

Operator certification in California is by grade (T1-T5 for treatment, D1-D5 for distribution); each grade requires specified experience, education, and passing an exam.

Continuing education: California requires 24 contact hours per 3-year renewal cycle for treatment operators, with specified subject categories.

Record retention: bacteriological and chemical monitoring results must be kept at least 5 years; turbidity and disinfection data at least 3 years; plans and specifications for the life of the facility.

Public notification for Tier 1 violations (e.g., MCL exceedance, treatment technique failure) within 24 hours; Tier 2 within 30 days; Tier 3 in the next CCR.

Sanitary surveys are required every 5 years for community water systems; significant deficiencies must be corrected within a specified schedule.

Chain of custody documentation is required for compliance samples, including collector name, date, time, sample location, and analysis requested.

Distribution system minimum pressure is 20 psi under normal conditions; below 20 psi requires a boil water notice and investigation.

Finished water storage tanks must maintain a minimum chlorine residual of 0.2 mg/L at all points; turnover of at least once every 5 days is recommended to prevent stagnation.

Tank inspection intervals: interior inspection every 5 years for steel tanks and every 3-5 years for concrete; exterior inspection annually.

Storage tank design includes cathodic protection, vent screening (to exclude birds and insects), overflow protection with flap valves, and locked access hatches.

Water age in storage is reduced by tank mixing (submerged inlet, baffles, or mixers); stratification can cause thermal layering and dead zones.

Distribution sampling sites must be representative; coliform monitoring frequency depends on population served (e.g., 1 sample per 1,000 people per month, minimum 1).

Cross-connection control requires backflow prevention devices (RPZ, DCVA, PVB) tested annually by certified testers; air gaps are the highest protection.

Hydrant flushing removes sediment and stale water; unidirectional flushing sequences from source to extremities improve effectiveness.