Sewers, Stormdrains & Wastewater Treatment

Sewers, Stormdrains & Wastewater Treatment

Glossary of Terms

A | B | C | D | E-F-G | H-I-J | K | L | M-N-O | P-Q-R | S | T | U | WXYZ

Advanced Primary Treatment

During wastewater treatment at the Riverside Water Quality Control Plant, ferric chloride and organic polymers are added to the sedimentation tanks to help waste particles bond together in large enough masses to settle out.


An interceptor alignment is the location or route a pipeline will follow. This alignment is chosen during the final design phase.

Anaerobic Digestion

Used to treat wastewater, anaerobic digestion is a series of processes in which microorganisms break down biodegradable material in the absence of oxygen. As part of an integrated waste management system, anaerobic digestion reduces the emission of landfill gas into the atmosphere.

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Biological Treatment

Biological water treatment involves the use of naturally occurring micro-organisms in ground water to improve water quality. Under optimum conditions, including enough oxygen, the organisms break down material in the water such as dissolved organic carbon (DOC) and iron and thus improve water quality. Sand or carbon filters are used to provide a place on which these micro-organisms grow.


Digested solids removed from wastewater.

BOD (Biochemical Oxygen Demand)

A gross measure of wastewater strength. The regional plant uses an accelerated treatment process in which living bacteria, thriving in an oxygen-rich environment, consume material in the wastewater. Industry wastewater that is high in BOD requires more oxygen and is therefore more expensive to process.


Best management practices.

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A small sewer access hole through which equipment may be lowered for trouble-shooting or maintenance work.


Small sewer pipes measuring twelve inches or less in diameter.


Co-production of electrical and thermal energy, also called combined heat and power (CHP).

Commercial Sewer Customer

Any business that produces wastewater, except a business that falls under the definition of an industrial sewer customer.

Conventional Tunneling

Methods of tunnel construction ranging from manual excavation to the use of self-propelled tunnel boring machines. Where an initial lining is required, bolted segmental rings are frequently used. The tunnel boring machine supports the ground during excavation and provides a place to erect the tunnel support. (If the tunnel support is not the final liner then it is considered two-pass tunneling).

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To remove chlorine from water.


Process by which organisms break down sludge, creating as by-products methane gas, carbon dioxide, solid organic material and water. (Aerobic digestion takes place in the presence of oxygen and anaerobic digestion takes place with the absence of oxygen.)


Final step in the tertiary wastewater treatment process, when chlorine or sodium hypochlorite is added to the treated wastewater to kill disease-causing organisms. Ultraviolet light is another means of disinfection.

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Also called utility easement, this is a portion of land, shared by a property owner and a public agency that contains a public utility, such as a sewer pipeline.


Treated, or partially treated, wastewater.


Equivalent single family dwellings.

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Force Main

A pressurized pipeline that actively carries wastewater from one area to another. The word "force" refers to the fact that the pipeline uses pressure, provided by pumping stations, rather than gravity to move flows. Pumping stations and pressurized force mains typically convey wastewater out of low-lying areas or over high ground to gravity-fed sewers that then deliver flows to the treatment plant.

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Grit Chamber

Tank in which the flow of wastewater is slowed, allowing heavy solid materials such as pebbles, sand, coffee grounds and eggshells to sink to the bottom.

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Area of treatment plant where influent begins treatment. - I - I/I (Infiltration and Inflow): Infiltration is water (typically groundwater) entering the sewer underground through cracks or openings in joints. Inflow is water (typically stormwater or surface runoff) that enters the sewer from grates or unsealed manholes exposed to the surface.

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Industrial Sewer Customer

Industrial Sewer Customer shall mean all persons and entities, public or private, industrial, commercial, governmental, or institutional which discharge or cause to be discharged, wastewater other than domestic sanitary wastewater and/or waterborne waste into the collection system of the City or Collection Agency, or City POTW treatment plant, including liquid waste haulers.


Untreated wastewater - the wastewater that flows into a wastewater treatment plant.


Large sewer pipes, some as large as 12 feet in diameter, which form the backbone of a wastewater transport system.

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Maintenance Hole

A sewer access large enough for a person to enter to trouble-shoot service problems or perform maintenance work.


A structure that allows access to the sewer system.


Abbreviation for millions of gallons / millions of gallons per day.

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NPDES - National Pollution Discharge Elimination System

The Clean Water Act established the National Pollution Discharge Elimination System (NPDES) program to help identify and reduce the source of pollution to waterbodies.

NPDES MS4 Permits

Municipal Separate Stormwater Sewer Program permit (MS4), originally approved in 1990, and currently under review for its fourth term re-issuance by the Santa Ana Regional Board. Regulates activities related to the quality of discharge through the stormwater management program.

The City of Riverside has been issued multiple NPDES permits, including one for the citywide municipal activities and one for the wastewater treatment plant's operations.

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A location where safe, treated wastewater is discharged into a river, ocean or other body of water. The outfall for the Riverside Water Quality Control Plant is on the Santa Ana River.

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Porter Cologne Water Quality Control Act

California's water quality compliance is legislated through the Porter-Cologne Water Quality Control Act.

Potable Water

Primary Treatment

A series of mechanical processes that remove solid material from wastewater. At the Riverside Water Quality Control Plant, primary treatment includes screening and settling processes.

Publicly Owned Treatment Works (POTWS)

Publicly owned treatment works (POTW) facilities are owned by a municipality, state, an intermunicipality or interstate agency, and departments/agencies of the federal government. The definition of a POTW facility includes intercepting sewers, outfall sewers, sewage collection systems, pumping, power, and other equipment.

Pumping Station (a.k.a. "lift station")

Sewer pipes are generally gravity driven. Wastewater flows slowly downhill until it reaches a certain low point. Then pumping, or "lift," stations push the wastewater back uphill to a high point where gravity can once again take over the process.

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Raw Sewage

Untreated wastewater.

Recycled Water

Treated wastewater that undergoes additional, advanced treatment to make it safe for non-potable uses such as landscape irrigation.


The upgrading of older sewer systems, constructed in the 1950s or earlier, to present-day standards.

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SAR Reach 3

The stretch of the Santa Ana River near the City of Riverside.

One of three waterbodies that exceeds water quality standards, as established by both the federal and state governments, requiring a Total Maximum Daily Load (TMDL).

Secondary Treatment

Biological and mechanical processes that remove dissolved organic material from wastewater. At the Riverside water Quality Control Plant, secondary treatment includes a biological process occurring inside oxygen reactor tanks and a settling process.

Sedimentation Tank

Waste water is passed through a series of tanks following coarse screening to remove large objects. Grit chambers settle out sand and cinders; primary settling tanks remove heavy organic solids.


A fluid, mainly water mixed with bentonite and sometimes polymers, used in a closed loop system for the removal of spoil and for the balance of groundwater pressure during tunneling and microtunneling operations.

Storm Drain

A pipeline or channel system that carries surface water and/or runoff to public waters, but does not feed into sewer system.


Consists of runoff from rain, irrigation and other urban and rural sources.

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Tertiary Treatment

The use of filtration to remove microscopic particles from wastewater that has already been treated to a Secondary Level.


Total Maximum Daily Load - A TMDL is a calculation of the total amount of a pollutant that a waterbody can receive to meet water quality standards; a TMDL also is the strategic plan and implementation requirements for how stakeholders will meet water quality standards.

TSS (Total Suspended Solids)

A measure of the amount of solids in the wastewater. Wastewater is passed through a filter and the amount of material captured is measured relative to the amount of wastewater filtered.

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Also known as sewage, wastewater includes the water you flush down your toilet and the water that drains from your bathtub, sink, washing machine and many other domestic sources. Businesses and industries also produce wastewater.

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General Information
3900 Main Street - 4th Floor
Riverside, CA 92522

Phone: (951) 826-5341

Monday - Friday 7:30am - 5:30pm
Closed Major Holidays
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