ABC Wastewater Collection Class II flashcards

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

Confined space definition

A space with limited entry/exit, not designed for continuous occupancy, and large enough for entry; examples include manholes, wet wells, and tanks.

Atmospheric testing order

Test oxygen first (19.5-23.5%), then flammables (<10% LEL), then toxics (H2S <10 ppm, CO <35 ppm) before and during confined space entry.

Entry permit

A document required for permit-required confined space entry that identifies hazards, atmospheric testing results, ventilation, PPE, and rescue plan.

Lockout/tagout

Procedure to isolate energy sources (pumps, mixers) before maintenance or entry; verify zero energy to prevent accidental startup.

Manning's equation

Q = (1.486/n) * A * R^(2/3) * S^(1/2) for open channel flow in English units; used to calculate flow in sewers.

Self-cleansing velocity

Minimum flow velocity of about 2 ft/s in sanitary sewers to prevent solids deposition; maximum velocity about 10 ft/s to avoid erosion.

Infiltration and inflow

Infiltration is groundwater entering sewers through defects; inflow is stormwater entering through direct connections; both increase flow and require rehabilitation.

Hydraulic grade line

The line representing the energy grade of flowing water; must be below manhole rim to prevent surcharging in gravity sewers.

CCTV inspection

Closed-circuit television camera used to inspect sewer interiors; identifies cracks, roots, offsets, and infiltration; record and code defects.

Smoke testing

Blows smoke into sewers to locate inflow sources; notify public and fire department beforehand to avoid false alarms.

CIPP rehabilitation

Cured-in-place pipe: a liner impregnated with resin is inserted and cured to form a new pipe within the old one; trenchless method.

NPDES permit

National Pollutant Discharge Elimination System permit required for wastewater discharges; includes effluent limits, monitoring, and reporting requirements.

SSO reporting

Sanitary sewer overflows must be reported to the state agency within a specified time (often 24 hours); include volume, location, and corrective actions.

Pretreatment program

Local program controlling industrial discharges to protect treatment plant, workers, and receiving waters; includes permits, monitoring, and enforcement.

Grease trap maintenance

Regular removal of fats, oils, and grease from interceptors prevents blockages and SSOs; frequency depends on use and size.

Odor control methods

Chemical addition (chlorine, hydrogen peroxide, ferrous salts), biofilters, and covers reduce odors from sewers and treatment plants.

Detention time formula

t = Volume / Flow; ensure consistent units (e.g., gallons and gallons per day) to calculate time in days.

Flow rate conversion

1 cubic foot per second (cfs) = 448.8 gallons per minute (gpm); 1 million gallons per day (MGD) = 1.547 cfs.

Pump horsepower formula

HP = (Q * H * SG) / (3960 * efficiency) for centrifugal pumps; Q in gpm, H in feet, SG = specific gravity.

Chemical dose formula

lbs = (concentration, mg/L) * (volume, MG) * 8.34; used to calculate chemical feed for treatment.

Lift station purpose

Lifts wastewater when gravity flow is not possible; includes wet well, pumps, controls, and emergency power.

Pump maintenance

Regular inspection of impellers, seals, bearings, and check valves; monitor vibration and temperature to prevent failures.

Wet well cleaning

Remove grit and debris to prevent pump clogging and reduce wear; schedule based on accumulation.

Emergency power testing

Test generators regularly and ensure automatic transfer switches function; critical for lift stations during power outages.

Preventive maintenance scheduling

Inspect and clean sewers on a frequency based on pipe material, age, slope, and history; ranges from monthly to every 5 years.

Root control

Use mechanical cutting or chemical foaming to remove roots from sewers; repeat as needed, especially near mature trees.

SSO emergency response

Have a plan for sanitary sewer overflows: contain, clean up, notify public and regulators, and document corrective actions.

Asset management

Inventory assets, assess condition, prioritize maintenance, and plan capital improvements to sustain collection system performance.

CMMS

Computerized maintenance management system: tracks work orders, inventory, and maintenance history for efficient operations.

Public notification

Inform public of SSOs, projects, or health hazards using door hangers, websites, social media, and public meetings.

Record retention

Retain monitoring records, maintenance logs, and inspection reports for at least 3 years or longer as required by permit.

Biosolids regulations

40 CFR Part 503 governs biosolids management, including pathogen reduction and vector attraction reduction requirements.