CA Branch 1 flashcards

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

Surface Water Treatment Rule

Federal rule requiring filtered surface water systems to achieve 0.3 NTU in 95% of monthly samples, never exceed 1 NTU, and provide 3-log Giardia and 4-log virus removal or inactivation.

Primary vs secondary MCL

Primary MCLs are enforceable health-based limits such as nitrate 10 mg/L and arsenic 0.010 mg/L. Secondary standards address aesthetics like chloride 250 mg/L and TDS 500 mg/L and are non-enforceable federally.

GWUDI determination

Groundwater under the direct influence of surface water is identified by site inspection or microscopic particulate analysis. Such sources are regulated as surface water and require filtration and disinfection.

Nitrate acute health risk

Nitrate above 10 mg/L as nitrogen causes methemoglobinemia in infants by impairing oxygen transport. Results above 5 mg/L are confirmed with a second sample before enforcement action.

Jar test procedure

Rapid mix 1-2 minutes at 200-300 rpm, flocculate 15-20 minutes at decreasing speed, settle 15-30 minutes, then measure supernatant turbidity. The lowest settled turbidity identifies the optimum coagulant dose.

Alum alkalinity consumption

Each mg/L of alum dose consumes about 0.45-0.50 mg/L of alkalinity as CaCO3 and lowers pH. Ferric chloride consumes about 0.54 mg/L alkalinity per mg/L dose.

Surface overflow rate

Surface overflow rate equals flow divided by basin surface area, expressed in m3/d per m2. Typical values are 20-40 for alum flocs and 40-60 with tube settlers.

Zeta potential target

Zeta potential near zero millivolts indicates charge neutralization and good coagulation. Typical target range is -5 to +5 mV, while sweep-floc operation tolerates more negative values.

Filter media specifications

Rapid sand filters use effective size 0.45-0.55 mm and uniformity coefficient 1.3-1.5 with 24-30 inch beds. Dual media adds anthracite with 0.9-1.1 mm effective size above the sand.

Backwash bed expansion

Backwash rates of 15-20 gpm/ft2 produce 20-30% bed expansion for 8-15 minutes. Air scour at 3-5 scfm/ft2 improves cleaning in dual media filters.

Filter-to-waste purpose

Filter-to-waste diverts the first 15-30 minutes of filtered water after backwash to drain, preventing a turbidity spike from entering the clearwell and causing a treatment technique violation.

Individual filter effluent limit

Individual filter effluent must remain below 1.0 NTU. Two consecutive 15-minute readings above 1.0 NTU constitute a significant deficiency requiring reporting and corrective action.

CT concept

CT equals disinfectant residual concentration in mg/L multiplied by contact time in minutes. Required CT depends on disinfectant type, pH, temperature, and target log inactivation.

Chlorine species and pH

Below pH 7.5 hypochlorous acid dominates and is about 80 times more effective than hypochlorite ion, which dominates above pH 8.0. Lowering pH improves disinfection efficiency.

Chlorine demand

Chlorine demand equals applied dose minus residual after a specified contact time. It reflects oxidant consumption by organics, ammonia, iron, manganese, and other reducing agents.

TTHM and HAA5 limits

Total trihalomethanes are limited to 80 ug/L and five haloacetic acids to 60 ug/L, measured as locational running annual averages at each monitoring location.

Langelier Saturation Index

LSI equals measured pH minus pHs, the saturation pH. Near zero is balanced, negative is corrosive, positive is scale-forming; typical target is -0.5 to +0.5.

Lead and copper action levels

Lead action level is 0.015 mg/L and copper is 1.3 mg/L at the 90th percentile. Exceedance triggers corrosion control treatment, source water treatment, or public education.

Orthophosphate corrosion control

Adding 1-3 mg/L orthophosphate as PO4 forms a protective lead phosphate film on pipe surfaces. It is most effective when pH is adjusted to 7.5-8.5.

Chloride-to-sulfate mass ratio

CSMR above 0.5 increases galvanic corrosion risk in lead service lines. High chloride relative to sulfate promotes release of lead from pipe surfaces.

Pump affinity laws

Flow varies directly with impeller speed, head with speed squared, and power with speed cubed. A 10% speed reduction cuts power consumption by about 27%.

NPSH available

NPSHA equals atmospheric pressure head plus static suction head minus friction loss minus vapor pressure head. It must exceed NPSHR by at least 1-2 feet to prevent cavitation.

Brake horsepower formula

Brake horsepower equals (gpm × head in feet × specific gravity) divided by (3960 × pump efficiency). It represents the power delivered to the pump shaft.

4-20 mA loop scaling

In a 4-20 mA loop, 4 mA represents zero and 20 mA represents full span. A reading of 12 mA corresponds to 50% of the instrument's calibrated range.

Chemical dose formula

Dose in mg/L equals (feed rate in lb/day × 1,000,000) divided by (flow in MGD × 8.34). Rearranged, feed rate equals dose × flow × 8.34.

Detention time calculation

Detention time in hours equals (basin volume in gallons × 24) divided by flow in gallons per day. Rectangular basin volume is length × width × depth.

Coliform sample hold time

Coliform samples are collected in 100 mL sterile bottles with sodium thiosulfate, stored on ice, and analyzed within 6 hours of collection to preserve valid results.

Chlorine gas IDLH

The IDLH for chlorine gas is 10 ppm, and the odor threshold is about 0.3 ppm. Chlorine is heavier than air and accumulates in low-lying areas during leaks.

Confined space atmospheric limits

Entry requires oxygen between 19.5 and 23.5%, flammables below 10% of the lower explosive limit, and hydrogen sulfide below 10 ppm, plus a permit and attendant.

Consumer Confidence Report deadline

Community water systems must deliver the Consumer Confidence Report to customers by July 1 each year, covering prior-year monitoring results, violations, and source water information.

Distribution minimum pressure

Distribution systems must maintain at least 20 psi under normal conditions. Pressure below 20 psi requires a boil water notice, investigation, and corrective action.