ABC Wastewater Collection Class II key terms

Groundwater that enters a sewer system through defective pipes, joints, connections, or manhole walls. It is clear water that adds to flow without coming from plumbing fixtures or drains.

Storm water or surface runoff that enters a sewer through direct connections such as roof drains, yard drains, sump pumps, or manhole covers. It arrives quickly during rain events.

Shorthand for infiltration and inflow, the two categories of clear water that enter a sanitary sewer. Utilities track I/I to size capacity, plan rehabilitation, and reduce treatment costs.

A condition where flow rises above the normal pipe crown and pressurizes the sewer because downstream capacity is exceeded. Surcharging can force sewage out of manholes and into basements.

The imaginary line showing the pressure head plus elevation of water flowing in a pipe or channel. Comparing it to pipe elevations shows where a sewer will surcharge or overflow.

The drop in elevation of a sewer per unit of horizontal length, usually expressed as a percentage or as feet per 100 feet. Adequate slope keeps flow moving fast enough to prevent solids from settling.

The minimum flow speed, commonly about 2 feet per second, that keeps grit and solids suspended and moving so they do not settle and build up in a sewer.

Erosion of pipe material, protective coatings, or accumulated debris caused by fast or turbulent flow. It can damage concrete and mortar inverts over time.

A vertical access structure that lets crews enter, inspect, clean, and maintain a sewer line. It typically includes a frame and cover, cone or chimney, walls, and a benched invert.

The lowest interior point of a pipe or manhole channel, where the bottom of the flow line sits. Invert elevations are used to calculate slope and confirm alignment between structures.

A facility with pumps and controls that raises wastewater to a higher elevation so it can continue flowing by gravity. Lift stations serve areas too low or too flat for a gravity sewer.

The tank or chamber at a lift station that receives incoming wastewater and holds it until pumps draw it down. Pump start and stop levels are set within the wet well.

A graph showing the relationship between the flow a pump delivers and the head it must overcome. It is compared with the system curve to find the actual operating point.

The total resistance a pump must overcome, including static elevation lift and friction losses in the piping. It is plotted against the pump curve to determine operating flow.

One complete on-off sequence of a pump filling and emptying the wet well between set levels. Excessive cycling shortens motor and pump life and can be reduced with proper storage volume.

A valve that allows flow in only one direction and closes automatically to prevent backflow. On a pump discharge it stops wastewater from flowing back into the wet well when the pump stops.

A space large enough to enter, with limited entry or exit, and not designed for continuous occupancy. Sewer manholes, wet wells, and vaults are typical examples in collection work.

A confined space that contains or may contain a hazardous atmosphere, engulfment, or other serious hazard. Entry requires a written permit, testing, ventilation, and an attendant.

Measuring oxygen, flammable gas, and toxic gas levels in a space before and during entry. Testing order is oxygen first, then flammables, then toxics such as hydrogen sulfide.

A toxic, flammable gas with a rotten-egg odor that forms from sewage decomposition in sewers. It can deaden the sense of smell at higher levels and is dangerous at low concentrations.

The trained person stationed outside a permit-required confined space who monitors entrants, maintains contact, and summons rescue. The attendant does not enter the space to attempt rescue.

A procedure that isolates and disables energy sources, such as pumps or electrical controls, before work begins. Each worker applies a personal lock and tag so equipment cannot be re-energized unexpectedly.

Closed-circuit television camera work that records the inside of a sewer to find cracks, roots, offsets, and blockages. Recordings are reviewed to grade condition and plan repairs.

A method of blowing non-toxic smoke into a sewer to reveal illegal connections and leaks. Smoke escaping from roofs, gutters, or ground shows where storm water or clear water enters.

Adding a visible dye to a fixture, drain, or pipe to trace where water flows. It is commonly used to confirm suspected illegal connections or cross-connections to the sanitary sewer.

Repair or renewal of a deteriorated sewer to restore structural integrity and flow capacity. Methods include cured-in-place pipe lining, pipe bursting, spot repairs, and manhole lining.

A trenchless repair where a resin-saturated liner is inserted into an existing pipe and cured in place to form a new inner wall. It restores strength and reduces infiltration without excavation.

Cooking fats, oils, and grease that are discharged to sewers and cool into sticky deposits. FOG builds blockages and is controlled through grease interceptors and public education.

A tank that slows flow so fats, oils, and grease float and are trapped before wastewater leaves a food service establishment. It must be pumped and maintained regularly to work.

The removal or reduction of pollutants from industrial or commercial wastewater before it enters the public sewer. Pretreatment protects pipes, treatment processes, and receiving waters.

A business that discharges nondomestic wastewater to the sewer and may be regulated by permit. Significant industrial users are monitored for flow, pollutant strength, and compliance.

Pollutant concentration limits a utility sets for discharges to its sewer to protect workers, pipes, and treatment. They are enforced through permits, sampling, and reporting.

A release of untreated wastewater from a sewer or manhole before it reaches treatment. Overflows must be stopped, cleaned up, and reported to regulators within required timeframes.

An intentional diversion of wastewater around a portion of the collection or treatment system. Bypasses are allowed only under limited conditions and usually require notification and reporting.

A federal permit issued under the Clean Water Act that controls discharges to surface waters. For collection systems it sets requirements for overflows, reporting, and sometimes capacity management.

A management approach that documents how a utility plans, operates, and maintains its collection system to prevent overflows. It links performance goals, work practices, and reporting.

A structured practice of tracking the condition, value, and remaining life of system components to schedule repair and replacement. It helps utilities spend limited funds where risk is highest.

Measuring wastewater flow at selected points to understand dry-weather base flow and wet-weather response. The data supports capacity analysis, I/I studies, and overflow investigations.

The ratio of peak flow to average flow used to size sewers and pumps for the busiest hours. Higher peaking factors require larger capacity to avoid surcharging.

The energy lost to resistance as water moves through pipe, fittings, and valves. It increases with flow rate and pipe roughness and must be added to static lift when sizing pumps.