Decentralized Wastewater Glossary

Directional boring, also referred to as horizontal directional drilling, is a minimal impact trenchless method of installing underground utilities such as pipe, conduit, or cables in a relatively shallow arc or radius along a prescribed underground path using a surface-launched drilling rig.

Device consisting of concentrically grooved discs stacked one upon the other and used for removal of particles larger than a specific size; typically used in drip distribution systems.

All piping and parts between the point of pump discharge to the point at which the supply line exits a dosing tank or punmp tank.

Air relief device in a sipon dosing configuration consisting of piping that allows air to enter and exit as needed for proper component function

Physical or chemical process used to destroy or inactivate pathogenic microorganisms in wastewater to render them non-infectious; see also disinfection, chlorine; disinfection, ozone; and disinfection, ultraviolet (UV).

Spreading of effluent over and into the final receiving environment.

1. Scattering and mixing; 2. Repellant action of an electric potential on fine particles in suspension in water, as in a stream carrying clay.

Amount of molecular oxygen (O₂) dissolved in water, wastewater, or other liquid; commonly expressed as a concentration in milligrams per liter (mg/L), parts per million (ppm), or percent of saturation.

That portion of total solids that passes through a filter of 2.0 µm (or smaller) nominal pore sized under specified conditions.

Process of conveying wastewater or effluent to one or more components or devices.

Level, watertight structure that receives septic tank effluent and distributes it via gravity in approximately equal portions to two or more trenches or two or more laterals in a bed.

Device that receives effluent from one component, and conveys it to a subsequent component(s), (e.g., a distribution box, drop box, or manifold).

See lateral.

Media used to provide void space (usually in a dispersal component) through which effluent flows and is stored prior to infiltration (e.g., washed rock, aggregate, polystyrene blocks or beads, chambers, pipe, etc.).

Entire network of components that transport wastewater or effluent within a system.

Relative variability of effluent delivery over an infiltrative surface.

See switching valve.

Dissolved oxygen.

Water or liquid-carried waste from plumbing fixtures, appliances and devices such as toilets, bath, laundry, and dishwashers; see also, residential-strength wastewater.

See dosing event or dose volume.

Period between the initiation of one dosing event and the next; the period includes both the time “on” and the time “off”.

1. Amount of effluent delivered to the distribution system during a dosing event including the drainback volume, pipe fill volume and the delivered dose volume; 2. Amount of effluent delivered as determined by the pump on and pump off levels in a demand dosed system.

See dosing tank.

Occurrence of effluent delivery after a rest period.

Tank or compartment which provides storage of effluent and contains a device (pump or siphon) and associated appurtenances used to convey effluent to another treatment process or a final treatment and dispersal component; see also pump tank and siphon tank.

1. Direction water flows by gravity; 2. Location down-slope.

Terracotta or perforated plastic piping or other conduit that is used as part of a drainage system.

Valve that allows drainage of a distribution system.

Network of natural or artificial groundwater or surface water features including agricultural drain tile, cut banks, and ditches which intercept and divert surface water and/or lower groundwater.

Group of soils defined by frequency and duration of wet periods similar to those under which the soil developed.

Backflow of effluent into a pump tank after pump operation ceases during a dosing event; see also drainback volume.

Amount of effluent that flows back into a pump tank after pump operation ceases during a dosing event.

Movement of effluent out of a lateral by infiltration into the soil treatment area following a dosing event.

See soil treatment area.

1. Regarding collection of soil water to reduce saturation; see drain tile; 2. Regarding collection of effluent in the bottom of a media filter, see underdrain.

Fourth step in the sequential treatment processes that occur in a sequencing batch reactor (SBR).

Drop in the liquid level of a tank as a result of some phase of operation.

Measurement of the drop in liquid level in a dosing tank measured over time to calculate dosing/delivery rate; may be expressed as a pump delivery rate (PDR) or siphon delivery rate.

Application of effluent over a soil treatment area via tubing with flow regulating emitters, and associated devices and parts (including pump, filters, controls, and piping).

Pressurized distribution system that delivers small doses of treated effluent to an infiltrative surface through a network of piping, tubing with flow regulating emitters, and associated devices.

Drip distribution device that dispenses effluent to the infiltrative surface at a predictable rate; see also non pressure-compensating emitter, and pressure compensating emitter.

Above or below grade soil treatment area where final treatment and dispersal occurs via application of effluent to the infiltrative surface via pressurized drip tubing utilizing emitters; see also drip field, surface; drip field, subsurface; and drip tubing.

System that is designed to apply liquid based on the needs of the receiving vegetation using drip distribution technology.

Length of drip tubing extending from the supply manifold to the return manifold.

See drip tubing.

Small diameter flexible plastic tubing manufactured with emitters uniformly spaced along its length; see also drip emitter.

Component of a drip distribution system made up of a group of drip laterals that is managed as a single unit.

See instantaneous loading rate.

1. Device used for serial or sequential distribution of effluent by gravity flow to a lateral of a final treatment and dispersal component; addition of such a device adds a means of system management; 2. Device used to lower piping elevation.

Soil that exhibits no visible signs of moisture content.

Partially lined underground pit (regardless of geometry) into which drainage from roofs, basement floors or other such sources is discharged and from which the liquid seeps into the surrounding soil; if effluent (such as that from a septic tank) is discharged to such a component, it is considered a seepage pit.

See alternating drainfields.

Configuration in which the supply line is connected to a manifold at two points.

Control that operates two usually identical devices in a system (e.g., a duplex pump system).

Operating condition represented graphically as the intersection of the pump curve and system curve.

Structure or building, or any portion thereof which is used, intended, or designed to be occupied for temporary or permanent human living purposes including, but not limited to: houses, houseboats, mobile homes, motor homes, travel trailers, hotels, motels, and apartments.

1. Piping assembly which facilitates the removal of liquid and solid wastes as well as the dissipation of sewer gases; 2. Pipe specified for use in the removal of liquid and solid wastes and for the dissipation of sewer gases.

Variable component of total dynamic head (TDH); comprised of friction head which fluctuates with piping diameter, system configuration, and flow rate; see also head, static; and head, total dynamic.

See Escherichia coli.

See tank capacity.

Depth of liquid below the head space in a tank; see also head space and operating level.

Amount of precipitation that infiltrates and is held in surface storage.

Particle diameter of which 10 percent of the sample is finer by weight as determined by a sieve analysis; also known as D10.

Liquid flowing out of a component or device.

See effluent screen.

Physical, biological, and chemical characteristics of a liquid flowing from a component or device.

Removable, cleanable (or disposable) device installed on the outlet piping of a septic tank for the purpose of retaining solids larger than a specific size and/or modulating effluent flow rate.

Centrifugal pump that can (in addition to passing liquids) pass solids of a specific size in accordance with the diameter of the pump intake and discharges the resulting mixture under pressure to a subsequent system component.

Device used to detect an electrical signal to measure and record the total length of time a component has been in the operation phase.

An external electrical current forcing metal corrosion in the presence of an electrolyte (such as salt water or moist air).                     

Corrosion that occurs when an external electrical current flows through a metal in the presence of an electrolyte (usually water containing dissolved salts or acids). This current causes metal atoms to lose electrons and dissolve as ions, leading to material degradation, especially at the point where the current leaves the metal (called the anodic area)

Above-grade soil treatment area designed and installed such that the entire infiltrative surface is located above the original ground elevation using suitable imported soil material for fill; utilizes gravity, pressure-dosed gravity or low-pressure distribution; cover of suitable soil stabilizes the final grade, supports vegetative growth and sheds runoff; see also mound.

1. Height relative to a fixed point of known elevation such as sea level or a benchmark; 2. High place or position; 3. Drawing or diagram made by projection on a vertical plane; a two-dimensional drawing of the front, side, or back of a building.

Component of total dynamic head (TDH) described as the difference in elevation between the lowest effluent operational level in the dosing tank and the discharge point; the sum of elevation head and operating pressure constitutes the static head component of total dynamic head (TDH).

Newly identified compounds or substances that have the potential to adversely affect public health or the environment and for which there is no currently published health standard; see also trace organic contaminants.

Suspension of solids as a result of decreased surface tension due to the presence of an emulsifying agent or some substance that alters or prohibits normal microbial activity; see emulsifying agent.

Agent capable of modifying the surface tension of emulsion droplets to prevent coalescence; examples are soap and other surface-active agents, certain proteins and gums, water-soluble cellulose derivatives, and polyhydric alcohol esters and ethers; see also emulsification and emulsion.

Heterogeneous liquid mixture of two or more liquids not typically dissolved in one another, but held in suspension by forceful agitation or by emulsifying agents that modify the surface tension of the droplets to prevent coalescence; see also emulsification and emulsifying agent.

Auto-oxidation by organisms in biological processes.

Condition in which the soil is saturated with water in all layers from the upper boundary of saturation to a depth of 200 cm or more from the mineral soil surface; see also anthric saturation and episaturation.

Relative susceptibility of the natural environment to adverse impacts from an outside constituent.

Zone of saturation held above the main groundwater body by a slowly-permeable layer, or by impermeable rock or sediment; see also anthric saturation; and endosaturation.

Units of measure that standardize all land use types (housing, retail, office, etc.) to the level of demand created by one single-family housing unit.

Member of the coliform bacteria group normally present in human and animal intestines; indicator organism for fecal contamination in water; see also coliform bacteria, fecal; coliform bacteria, total; and indicator organism.

Highest recorded flow occurring within a short, specific period (expressed in gallons per minute).

See evapotranspiration bed.

See lined evapotranspiration bed.

See unlined evapotranspiration bed.

Nutrient enrichment of a lake or other water body typically characterized by increased growth of planktonic algae and rooted plants; can be accelerated by wastewater discharges and polluted runoff.

Process by which an element or compound transitions from its liquid state to its gaseous state below the temperature at which it boils; in particular, the process by which liquid water enters the atmosphere as water vapour in the water cycle.

lagoon where wastewater is stored and the water is allowed to evaporate over time.

Loss of water from the soil both by evaporation from the soil surface and by transpiration from the leaves of the plants growing on it. Factors that affect the rate of evapotranspiration include the amount of solar radiation, atmospheric vapor pressure, temperature, wind, and soil moisture.

Dispersal component with a continuous, impermeable bed liner that uses evaporation and transpiration for dispersal of effluent; sometimes called an evapotranspiration/adsorption (ETA) bed.

Device used to record the number of times a component or device has been activated or deactivated (e.g., pump activation is one event and pump deactivation is a second event).

Any man-made cut, cavity, trench, or depression in an earth surface, formed by earth removal.

Unintended/undesirable outflow of effluent from a component into the environment.

Natural, unaltered land surface; also referred to as original ground surface.