Wastewater Collection Operator Class I key terms

A pipe network that carries domestic and industrial wastewater from buildings to a treatment plant. It is designed to exclude stormwater, surface water, and groundwater so flows stay within its capacity.

Groundwater that seeps into a sewer system through cracks, broken joints, deteriorated pipe, and faulty manhole walls. It raises dry-weather flows and adds clear water the plant must treat.

Stormwater, drainage, or other water that enters a sewer directly through roof drains, sump pumps, manhole covers, and cross connections. Unlike infiltration, it arrives quickly during rain events.

The lowest inside surface of a pipe or channel at a given cross section. Operators use invert elevations to confirm slope and to measure how deep a sewer line lies.

A pressurized pipeline that carries wastewater discharged by pumps, usually from a lift station to a gravity sewer or treatment plant. Flow is driven by pressure, not by gravity.

A condition where flow exceeds a sewer's capacity and the water level rises above the pipe crown, putting the line under pressure. Surcharging can push wastewater out through manholes.

A technique where non-toxic smoke is blown into a sewer line and escaping smoke reveals cracks, illegal connections, and storm drains tied into the system. Crews notify the public before testing.

A toxic, corrosive gas formed when wastewater goes septic and sulfate is reduced under anaerobic conditions. It causes odors, attacks concrete pipe, and can be deadly in confined spaces.

Fats, oils, and grease that enter sewers from kitchens and food businesses. They cool and congeal on pipe walls, narrowing the line and causing blockages and overflows.

A pump that uses a spinning impeller to throw water outward into a casing, converting speed into pressure. It is the most common type used for wastewater and is best for high flows at low head.

A pump that moves a set volume of liquid each cycle by trapping it and pushing it forward with a piston, diaphragm, or rotary element. It suits thick sludges and low flows at high pressure.

The formation and collapse of vapor bubbles in a pump when local pressure drops below the liquid's vapor pressure. It causes noise, vibration, and pitting damage to the impeller and reduces capacity.

The absolute pressure at a pump's suction, expressed in feet of liquid, above the liquid's vapor pressure. Too little available NPSH causes cavitation and loss of capacity.

The total energy a pump must add to move liquid through a system, combining static lift, discharge elevation, and friction losses in pipe and fittings. It is measured in feet of liquid.

A graph supplied by the manufacturer showing the relationship between flow rate and head, plus efficiency and power, for a given pump at a set speed. Operators use it to match a pump to the system.

A valve that lets flow pass in one direction only and closes automatically when flow reverses. It protects pumps from backspin and keeps wastewater from flowing back into a wet well.

The chamber that receives incoming wastewater and holds it so pumps can draw from it. Pump start and stop levels in the wet well control the operating cycle.

An electronic controller that changes the speed of an electric motor by varying the frequency and voltage supplied to it. It lets pumps match flow demand and reduces energy use and starting stress.

A space large enough to enter, with limited access, not designed for continuous occupancy, and containing a serious hazard such as a hazardous atmosphere, engulfment, or entrapment. Entry requires a written permit and an attendant.

A procedure for isolating energy sources before work on machinery so equipment cannot start unexpectedly. Each worker applies a personal lock and tag, and the equipment is verified de-energized.

The lowest concentration of a flammable gas or vapor in air that will ignite when a spark is present. Monitors read in percent LEL, and readings of ten percent or more mean do not enter.

An atmosphere containing less than 19.5 percent oxygen by volume, the minimum considered safe for entry. Low oxygen can cause confusion and collapse without warning.

An engineered method such as sloping, benching, shoring, or a trench shield used to prevent cave-ins in an excavation. Trenches five feet deep or more require a protective system.

Disease-causing microorganisms carried in blood and body fluids, such as hepatitis B and HIV. Workers exposed to sewage or medical waste follow an exposure control plan and use protective equipment.

A standardized document from a chemical manufacturer listing hazards, handling precautions, first aid, and spill response for a product. Workers must be able to find one for every hazardous chemical on site.

Testing the air inside a confined space for oxygen, flammable gas, hydrogen sulfide, and carbon monoxide before entry and continuously while anyone is inside. Monitors are calibrated and bump tested regularly.

The federal law that governs water pollution in the United States. It set the framework for discharge permits, water quality standards, and funding for wastewater treatment and collection systems.

The National Pollutant Discharge Elimination System permit required by the Clean Water Act for any point-source discharge of pollutants to surface waters. Permits set limits, monitoring, and reporting requirements.

A release of untreated wastewater from a sanitary sewer system before it reaches the treatment plant. Overflows can be caused by blockages, infiltration, equipment failure, or excess flow, and most states require reporting.

A discharge of mixed stormwater and raw wastewater from a combined sewer when a rain event exceeds the system's capacity. These overflows are regulated and often addressed through long-term control plans.

Capacity, Management, Operations, and Maintenance, an EPA framework for keeping sanitary sewers in good condition. It calls for proactive programs covering flow capacity, maintenance, and overflow response.

A regulatory program that controls what industrial users may discharge into a publicly owned sewer so the treatment plant stays compliant and sludge stays usable. It relies on permits, inspections, and local limits.

The local law that sets the rules for connecting to and discharging into a municipal sewer, including prohibited wastes, fees, and permit requirements. It is the legal basis for local enforcement.

A state-issued credential showing that a wastewater operator has met education, experience, and examination requirements for a given grade. Certification must usually be renewed with continuing education.