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


Digested solids removed from wastewater.


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.


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.

Commercial sewer customer

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

Contributing agencies

With respect to the organizational structure of the Sacramento Regional County Sanitation District (SRCSD), contributing agencies collect wastewater, while SRCSD conveys (transports) and treats wastewater. SRCSDs contributing agencies are County Sanitation District One (SASD) and the cities of Sacramento and Folsom.

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).

Drilling fluid or mud

A mixture of water and usually bentonite and/or polymer continuously pumped to the cutting head to facilitate cutting, reduce required torque, facilitate the removal of tunings, stabilize the borehole, cool the head, and lubricate the installation of the product pipe. In suitable soil conditions water alone may be used.


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.


Earth Pressure Balance Machine (EPBM): Type of microtunneling or tunneling machine with a closed face and pressurized much chamber that supports the face of the tunnel and counterbalances the earth and groundwater pressures. This is done by filling the chamber with soil excavated from the tunnel and pressurizing it by pushing the machine forward and removing the muck from the chamber in a controlled manner through a screw conveyor. Polymer foams are utilized to plasticize the muck if sands and gravels are encountered in the excavation of the tunnel. The term is usually not applied to those machines where the pressure originates from the main pipe jacking rig in the drive shaft/pit or to systems in which the primary counterbalance of earth pressure is supplied by pressurize drilling fluid.


Equivalent single family dwellings.

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.


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.

Industrial sewer customer

Typically defined as any business: That discharges more than 25,000 gallons per day of wastewater to the sewer. That is subject to certain U.S. Environmental Protection Agency regulations (examples include metal finishers or electroplaters).


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.

Jacking shaft

Excavation from which trenchless technology equipment is launched for the installation or renewal of a pipeline.

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.


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


A trenchless construction method for installing pipelines. Microtunneling is remotely controlled and guided pipe jacking that provides positive control of the tunnel face.


A location where safe, treated wastewater is discharged into a river, ocean or other body of water. Also, the equipment and facilities at this location. The outfall for the Sacramento Regional Wastewater Treatment Plant is on the Sacramento River, near the town of Freeport.

Pipe jacking

Installation of pipe into the ground behind the tunneling machine using hydraulic jacks located in the jacking pit. The tunnel boring machine and jacking pipes are jacked into place from a jacking shaft to a receiving shaft on opposite ends to the drive such that the pipes form a continuous string in the ground. When the machine reaches the receiving shaft, it is retrieved and removed.

Potable water

Better known as drinking water.

Primary treatment

A series of mechanical processes that remove solid material from wastewater. At the Sacramento Regional Wastewater Treatment Plant, primary treatment includes screening and settling processes.

Pumping station (a.k.a. "life 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.

Reception shaft

Excavation into which trenchless technology equipment is driven and recovered following the installation of the product pipe, conduit or cable.

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.

Secondary treatment

Biological and mechanical processes that remove dissolved organic material from wastewater. At the Sacramento Regional Wastewater Treatment Plant, secondary treatment includes a biological process occurring inside oxygen reactor tanks and a settling process.


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.

Spoil (muck)

Earth, rock, and other materials displaced by a tunnel, pipe or casing, and removed as the tunnel, pipe, or casing is installed. In some cases, it is used to mean only the material that has no further user.


Sacramento Regional Wastewater Treatment Plant


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


Tunnel boring machine: A full-face circular mechanized shield machine, usually of worker-entry diameter, steerable, and with a rotary cutting head. For pipe jacking installation it leads a string of pipes. It may be controlled from within the shield or remotely such as in microtunneling. A mechanical excavator used in a tunnel to excavate the front face of the tunnel.


Total kjeldahl nitrogen: TKN is the combination of organically bound nitrogen and ammonia in wastewater.

Trunk lines

Sewer pipes measuring more than 12 inches in diameter and having a capacity of 1 to 10 million gallons per day. Trunk lines connect smaller sewer pipes, or collectors, to the largest transport pipes, or interceptors.


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.


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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