Wastewater Collection Operator Class III key terms

A confined space that contains or could contain a hazardous atmosphere, engulfment material, an internal configuration that can trap or asphyxiate a worker, or any other serious safety or health hazard.

Testing the air inside a confined space for oxygen content, flammable gases and vapors, and toxic gases before entry and continuously while workers are inside.

The lowest concentration of a gas or vapor in air that will ignite when exposed to an ignition source; readings are usually expressed as a percentage of this limit.

A written authorization prepared before confined space entry that identifies the space, hazards, controls, entrants, attendants, and rescue arrangements, and is retained after the job is finished.

The trained worker stationed outside a confined space who tracks entrants, maintains communication, controls access, and summons rescue without entering the space.

Retrieving an incapacitated worker from a confined space using a tripod, winch, or similar equipment operated from outside, avoiding the need for rescuers to enter.

A colorless, highly toxic gas with a rotten-egg odor that forms in septic wastewater; it deadens the sense of smell at higher concentrations and is a leading cause of sewer fatalities.

A work area set up with signs, cones, and barricades to guide vehicles safely around crews working in or near streets, following an approved traffic control plan.

A pipe network that carries only domestic, commercial, and industrial wastewater, plus limited groundwater and stormwater inflow, to a treatment plant.

A system that collects sanitary wastewater and stormwater runoff in the same pipes, often requiring overflow structures during heavy rain.

A discharge of untreated mixed wastewater and stormwater from a combined system when flows exceed capacity, typically to a receiving water during wet weather.

Extraneous water entering a sewer, either through defective pipes and joints (infiltration) or from direct connections such as roof drains and sump pumps (inflow).

The ratio of peak flow to average flow over a given period, used to size pipes and pumps so the system handles the highest expected loads.

The projected wastewater flow rate, including future growth and peaking allowances, that a pipe, pump, or treatment unit is sized to handle.

A formula relating pipe slope, roughness, and hydraulic radius to flow velocity in open-channel or gravity sewer flow, used to size and check lines.

The minimum flow velocity needed to keep solids suspended and prevent deposition in a sewer, commonly about two feet per second at design flow.

The lowest interior point of a pipe's cross section at a given location, used to set elevations, slopes, and drop connections.

A manhole with an internal vertical pipe or structure that carries flow down to the outgoing invert, dissipating energy where a steep incoming line meets a shallower one.

A strong, corrosion-resistant metal pipe made from cast iron treated for flexibility, often used for force mains, river crossings, and locations with high loads.

A lightweight plastic pipe joined by gasketed bell-and-spigot or solvent cement, widely used for gravity sewers because of its smooth interior and corrosion resistance.

Measuring how much a flexible pipe's diameter has deformed after backfill, usually with a mandrel or laser profiler, to confirm it meets the allowable ovality limit.

A new-sewer acceptance test in which the plugged line is pressurized with air and the time required for a set pressure drop is measured to reveal leaks.

Removing grease, roots, and debris by jetting water at high pressure through a nozzle pulled through the pipe, with flows controlled and contained.

Cutting or chemical treatment of tree roots that have entered sewer joints and laterals, followed by inspection to confirm the pipe is clear.

A rehabilitation method in which a resin-saturated liner is inserted into a damaged sewer and cured in place to form a new structural pipe wall.

Repair or replacement of buried pipe with minimal excavation, using methods such as lining, pipe bursting, or slip lining to extend asset life.

A pressurized pipe that carries wastewater pumped from a lift station to a point where gravity flow can resume.

A facility with pumps and controls that raises wastewater from a lower elevation to a higher one so it can continue flowing by gravity.

The chamber at a lift station that receives incoming wastewater and holds it while pumps draw it down, with levels controlled by floats or sensors.

A device installed at high points on a force main to vent trapped air that would otherwise reduce pumping capacity or cause damaging pressure surges.

A pressure surge caused by a sudden change in flow velocity, such as a pump stopping or a valve closing quickly, that can rupture pipes and fittings.

Recording the inside of a sewer with a camera-mounted crawler to document defects, verify cleaning, and support condition rating decisions.

Blowing non-toxic smoke into a sewer to find illegal connections, broken pipes, and cross-connections where smoke escapes into buildings or the ground.

A standardized score assigned to pipe segments based on observed defects, used to rank rehabilitation needs and plan capital spending.

A federal permit, administered by states, that sets limits and monitoring requirements for wastewater and stormwater discharged to waters of the United States.

A release of untreated wastewater from a sanitary sewer system before it reaches treatment, which must typically be reported to regulators within set timeframes.

Notifying the regulatory agency when wastewater is diverted around part of the treatment process or collection system, including volume, duration, and corrective action.

A systematic approach to tracking the condition, value, and remaining life of collection system components so repair and replacement spending is prioritized.

A written record authorizing and describing a maintenance or repair task, including location, labor, materials, and completion notes for the asset history.

A step-by-step review of a task that identifies hazards at each stage and specifies controls, training, and protective equipment before work begins.

A written procedure describing how crews will respond to spills, injuries, equipment failures, and other incidents, including roles, contacts, and notification steps.