MD Water Operator flashcards
MD Water Operator · Build recall with a focused review session.
32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- CT value
- Product of disinfectant residual concentration (mg/L) and contact time (minutes). Required CT depends on disinfectant, pH, temperature, and the log inactivation credit needed.
- Log inactivation
- A 10-fold reduction in pathogen concentration equals 1 log. Required credit is the target log reduction minus credit for physical removal by filtration.
- Turbidity limit
- For conventional filtration, individual filter effluent must be ≤ 0.3 NTU in 95% of monthly measurements and never exceed 1 NTU.
- Jar test purpose
- A bench test that determines the optimum coagulant dose and pH for coagulation and flocculation by simulating treatment conditions on a small sample.
- Cryptosporidium control
- Chlorine is largely ineffective against Cryptosporidium. Physical filtration plus UV or ozone disinfection is used to achieve required inactivation.
- Backwash trigger
- A filter is backwashed when head loss reaches the terminal value or effluent turbidity breaks through, using a rate that fluidizes the bed without media loss.
- Chlorine MRDL
- The maximum residual disinfectant level for chlorine and chloramine is 4.0 mg/L (as Cl2). Distribution residual must generally stay at or above 0.2 mg/L.
- Minimum distribution pressure
- Design pressure must be at least 20 psi at all points in the distribution system, including during fire flow. Pressure below 20 psi requires a boil-water notice.
- Air gap
- The only true backflow prevention method: a physical separation between the potable water outlet and the flood-level rim of the receiving vessel.
- RPZ assembly
- A reduced-pressure-zone backflow preventer that protects against both backpressure and backsiphonage; it is testable and requires annual testing.
- Water age
- The time water resides in the distribution system. High age causes disinfectant loss, nitrification, and taste/odor problems; reduced by looping and flushing.
- Hydrant flow test
- A test using a pitot gauge and nozzle coefficient to measure flow and residual pressure, used to estimate available fire flow and system capacity.
- Non-revenue water
- Water produced minus water billed. It includes leaks, flushing, and unauthorized use; well-run systems typically keep it under 10-15 percent.
- Main-sewer separation
- Water mains must generally be at least 10 feet horizontally from sewer lines, or use specified vertical separation and casing to prevent contamination.
- Total coliform rule
- Sets an MCL based on the percentage of positive samples per month and requires repeat sampling within 24 hours of any positive result.
- E. coli violation
- Presence of E. coli in distribution is a Tier 1 violation requiring public notice within 24 hours and immediate corrective action.
- GWUDI
- Groundwater under the direct influence of surface water. It must be treated as surface water, requiring filtration and disinfection unless avoidance criteria are met.
- Nitrate MCL
- The nitrate limit is 10 mg/L as nitrogen. It indicates agricultural or septic contamination and poses a risk to infants (blue baby syndrome).
- Turbidity monitoring
- Turbidity is measured continuously at each filter, with grab samples for verification. Values above 1 NTU require investigation and corrective action.
- Source water assessment
- Delineates protection zones around intakes and wells and identifies potential contamination sources to guide wellhead and watershed protection.
- Primary versus secondary MCL
- Primary MCLs protect health (e.g., nitrate, arsenic, lead action level). Secondary standards address aesthetics such as taste, odor, color, and corrosivity.
- Consumer Confidence Report
- An annual report delivered to customers by July 1 that lists source water, detected contaminants, and compliance status.
- Public notice tiers
- Tier 1 (immediate health risk) within 24 hours; Tier 2 within 30 days; Tier 3 within one year. Violations must be reported to the primacy agency.
- TTHM and HAA5
- Disinfection byproduct MCLs: TTHM 0.080 mg/L and HAA5 0.060 mg/L, evaluated as locational running annual averages.
- Lead and copper action level
- Lead action level 0.015 mg/L and copper 1.3 mg/L. Exceedance triggers corrosion control, source water treatment, and public education.
- Operator certification renewal
- Certification requires passing an exam and meeting experience requirements; renewal requires continuing education units (CEUs) and is tracked by the primacy agency.
- Confined space testing
- Before entry, test for oxygen (19.5-23.5%), flammables (LEL under 10%), H2S (under 10 ppm), and CO (under 35 ppm); use a permit and attendant.
- Lockout/tagout
- Isolates hazardous energy before maintenance. Apply a personal lock, verify zero energy state, and restore energy only after all workers clear.
- Chlorine gas hazard
- Chlorine gas is heavier than air and highly toxic. Responders must use SCBA, not a dust mask, and use leak detection and emergency kits.
- H2S hazard
- Hydrogen sulfide is heavier than air, an asphyxiant, and flammable. It deadens the sense of smell at higher concentrations, so never rely on odor.
- Trench protective system
- Trenches 5 feet deep or more require a protective system (shoring, shielding, or sloping). Spoil and equipment must be kept at least 2 feet from the edge.
- Rate-setting principle
- Rates should recover the full cost of service: operation, maintenance, debt service, and reserves. Structures include uniform, increasing block, and seasonal rates.