Decentralized Wastewater Glossary

Portion of the water below the surface of the ground at a pressure equal to or greater than atmospheric; see also water table.

See interceptor drain.

Assembly of components and devices designed to actively or passively lower the water table beneath a soil treatment area.

Localized increase in the elevation of a water table that results from the downward percolation of additional liquid toward groundwater.

Stake, strip, or lath placed beside a hub stake to identify it.

Component malfunction that disrupts the overall system performance and constitutes an immediate public and environmental health and safety risk.

1. Portion of piping or conduit extending from its bottom to the spring line; 2. Lower third of the circumference of a cylindrical tank; 3. Portion of non-straight-walled tank below the horizontal plane defined by its greatest width; see diagram at bedding.

Portion of an excavation where the haunch of a pipe, conduit, tank or structure is located; see diagram at bedding.

Material placed around piping, conduit, tank, or component for uniform structural support within the haunch zone; (2) placing backfill or embedment around a conduit or structure in an excavation such that the void area is stabilized; see diagram at bedding.

Atmosphere which by reason of being explosive, flammable, poisonous, corrosive, oxidizing, irritating, oxygen deficient, toxic, or otherwise harmful, may cause death, illness, or injury.

Energy, either velocity or potential, possessed by each unit weight of a liquid, expressed as the vertical height through which a unit weight would have to fall to release the average energy possessed; used in various compound terms such as pressure head, elevation head, velocity head, and friction head; typically measured in feet of liquid or pounds per square inch (psi).

Change in pressure between two points in an operating system as a result of friction and/or a change in elevation; also called pressure loss.

A geomorphic component of hills consisting of a laterally concave area of a hillside, especially at the head of a drainageway, resulting in converging overland water flow (e.g., sheet wash); head slopes are dominated by colluvium and slope wash sediments (e.g., slope alluvium); contour lines form concave curves.

1. Volume between the invert of the outlet and the inside top of a septic tank or a trash tank, also known as freeboard; 2. Volume between the invert of the tank inlet and the inside top of a dosing tank; see also reserve volume.

See manifold.

All parts and/or devices between the discharge assembly and the distribution laterals (including filtration devices, valves, gauges, and pressure regulators), used to control the quality, rate, pressure, and direction of flow of effluent; typically used in a drip distribution system.

Elevation of the line of sight of the surveying instrument; determined by adding the Backsight (BS or +) to the known elevation of the point upon which the rod reading was taken, usually a benchmark or turning point.

Worm-like organism that can infect humans and other animals; constituent of concern in biological wastewater treatment.

Standard procedure for estimating the total number of live non-photosynthetic bacteria in water; colony-forming units (CFU) are counted after spreading an aliquot of a sample over a membrane or pour plate and incubating in an amiable growth medium (agar) at an amiable temperature; see also colony-forming unit (CFU).

See centrifugal pump.

1. Influent having BOD5 greater than 300 mg/L; and/or TSS greater than 200 mg/L; and/or fats, oils, and grease greater than 50 mg/L entering a treatment component (as defined by NSF Standard 40 testing protocol); 2. Effluent exiting a septic tank or other pretreatment component that has BOD5 greater than 170 mg/L; and/or TSS greater than 60 mg/L; and/or fats, oils, and grease greater than 25 mg/L and is applied to an infiltrative surface.

1. Watertight receptacle for the collection and holding of wastewater; 2. Sewage tank in a recreational vehicle, motor coach, trailer, camper, or boat, whether mobile or stationary; see also holding tank sewage system.

System which combines or utilizes a holding tank with alarm, the services of a sewage pumper/hauler, and off-site treatment of the collected sewage.

See soil horizon.

Short stake placed at a station and driven almost flush with the ground; hub stakes are used to obtain station elevations in drainage and other kinds of elevation work; also called a hub.

Measure of the chromatic composition (wavelength) of light that reaches the eye; one of the three variables of color; see also Munsell Color System, chroma, and value.

Measurement of the flow of liquid through an area perpendicular to the flow direction.

The surface or profile of water flowing in an open channel or a pipe flowing partially full. If a pipe is under pressure, the hydraulic grade line is at the level water would rise to in a small tube connected to the pipe. To reduce the release of odors from wastewater, the water surface or hydraulic grade line should be kept as smooth as possible.                                                                 

Quantity of liquid applied to a component surface area or capacity in a time interval, usually expressed as volume applied in a time interval to a surface area (e.g., gallons per day per square foot [gpd/ft²]), or capacity (e.g., gallons per day, hour or minute).

Biogeochemical cycle that continuously circulates water through the earth-atmosphere system via processes including evaporation, transpiration, condensation, precipitation, and runoff. 

Conversion of constituents to sugars, acetic acid, and fatty acids.

See grease separator.

Having a strong affinity (liking) for water; the opposite of hydrophobic.

Having a strong aversion (dislike) for water; the opposite of hydrophlic.           

Infiltration and inflow; term used to describe the combined undesirable entry of extraneous water into a system component; see also infiltration and inflow.

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

See integrated fixed-film activated sludge .

The total oppostion to an alternating current presented by an electrical circuit. Expressed in ohms.               

A rotating device that increases the pressure and flow of a liquid.

Not permitting the passage of fluid through pores; in practical terms, some small level of hydraulic conductivity may occur, but at so low a level (e.g., 1 x 10-7 cm/s) that it is negligible.

Resistant to penetration or passage by fluids or by roots.

See below-grade.

Device installed as a part of the piping in a system, operated under pressure and designed to remove suspended solids from wastewater.

Organism that can be readily detected, the presence of which infers the presence of other microorganisms (e.g., fecal coliform bacteria is an indicator of probable presence of pathogens); see also coliform bacteria, fecal and coliform bacteria, total.

Wastewater treatment system designed to serve one sewage-generating dwelling or facility.

The production of magnetization of electrification ina body by the proximity of a magnetic field or electrical charge, or of the electric current in a conductor by the variation of the magnetic field in its vicinity . Expressed in Henrys.

Water or liquid-carried waste from an industrial process resulting from industry, manufacture, trade, automotive repair, vehicle wash, business or medical, activity; this wastewater may contain toxic or hazardous constituents.

number of microorganisms that would initiate an immunological response by a host.

1. Wntry of water or effluent into the soil; 2. Undesirable inflow or seepage of water into a system component; for example, infiltration of surface water into a tank through a leaking pipe, pipe penetration, or through an access riser/tank seam that is not water-tight.

Designated interface where effluent moves from distribution media or a distribution device into treatment media.

Extraneous water entering a component directly, such as via a sump pump, foundation drain, storm gutter or condensate drain.

Liquid entering a component or device.

Physical, biological, and chemical characteristics of the liquid flowing into a system component or device.

Portion of an excavation above the haunch zone or bedding with a depth of 6-12 inches (15 to 30 cm) above the piping, conduit tank, or structure; see diagram at bedding.

Well by which effluent is transmitted to an underground formation; in most cases these are regulated and require a permit from a regulatory authority.

Piping that conveys wastewater or effluent into a component.

Pipe tee or wall segment located at or near the inlet pipe of a septic tank and designed to dissipate energy, direct flow below the liquid surface, isolate scum from the inlet pipe, and allow ventilation.

See alternative onsite wastewater treatment system.

Non-carbon-based molecules such as minerals and salts.

Forms of phosphorus from mineral sources, such as orthophosphate, pyrophosphate (P2O7-4), and tripolyphosphate (P3O105-).

Evaluation of and reporting on the status of a wastewater treatment system.

Access point in a system component that enables inspection, operation and maintenance.

Service provider who evaluates and reports upon the status of a wastewater treatment system.

To put in place or construct components.

Assembly and placement of components of a system, including final site grading and establishment of an appropriate cover.

Service provider who is compensated to construct a wastewater treatment system.

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

Quantity of liquid applied to a component surface area or capacity in a short time interval, expressed as volume per unit time, (e.g., gallons per minute [gpm]) or volume per unit time per unit area (gpm/ft²).

Wastewater treatment process that incorporates both activated sludge and fixed-film treatment to biologically convert non-settleable (suspended, dissolved, and colloidal) organic materials to a settleable product using aerobic and facultative microorganisms.

Combination of grab samples collected at a similar time but at different locations.

System in which treatment components are installed directly into the soil treatment area, so that both treatment and dispersal processes occur in a single location.                         

Subsurface drain used to intercept and divert laterally moving groundwater or perched water away from the soil treatment area or other system component to an effective outlet; see also perimeter drain.

Landform composed of the relatively undissected upland or ridge between two adjacent valleys containing streams flowing in the same general dierction.

A broad, nearly level "summit" or interfluve; see also interfluve.

Elevation of the bottom of the inside pipe wall or fitting.

Reversible chemical process in which electrically charged particles are exchanged between a solution and a solid.

Measure of light “intensity” at the surface; the radiant power arriving at a point on a surface, per unit area (mW/cm²)

Valve that is placed before or after a piece of equipment in case that equipment may need to be removed from service.

Device that uses pressurized water conveyed through a hose with a special nozzle to dislodge and break up foreign material.

Metal or hard plastic electrical box, housing only wire or cable connections; in exterior locations, must be watertight.

Accidental release or failure of a cross brace.

Combination of ammonia nitrogen (NH₃) and organic nitrogen in a wastewater sample; total kjeldahl nitrogen is operationally defined by a method that involves digestion of a sample followed by distillation and determination of ammonia (NH₃) in the distillate; see also ammonia nitrogen; organic nitrogen; and total Kjeldahl nitrogen (TKN).

Saturated hydraulic conductivity.

Material deposited in lake water and later exposed either by lowering of the water levewl or by the elevation of the land.

Constructed basin lined with either soils with very low permeability or a synthetic material, surrounded with berms and which contains at least three feet of wastewater and which utilizes sunlight, wind or mechanical aeration and natural bacteria to break down waste via physical, chemical, and biological processes.

Process in which biosolids or liquid waste treatment residuals are spread over, sprayed onto, or injected into the soil.

Removal of vegetation including root mass.

Plane survey made for locating property lines, subdividing land into smaller parts, and determining land areas and other information involving the transfer of land from one owner to another; also known as a property survey, boundary survey, or cadastral survey.

Physical, recognizable forms or features on the earth surface, having a characteristic shape and produced by natural causes.

Portion of the land surface that the eye can comprehend in a single view.

Cumulative total of effluent applied to the soil profile at the perimeter of a dispersal system, describing the effluent dispersal to the receiving environment in a time interval, expressed as volume per unit length per unit time to the window of acceptance (e.g., gpd/ft); see also contour loading rate, and window of acceptance.

See landscape linear loading rate.

Position describing the location of the soil on the landscape; two-dimensional landscape positions may be summit, shoulder, backslope, sideslope, footslope, or toeslope; three dimensional views of geomorphic landscape position can be described as headslope, noseslope, sideslope, base slope, etc.; site drainage characteristics include intermittent drainageways, active drainageways or other flood-prone areas.                                                                               

Level that employs the use of a laser projected on a target.

Pipe, tubing or other conveyance used to carry and distribute effluent.

Ninety- or forty-five-degree change in piping orientation from horizontal to diagonal and/or vertical at the end of a pressure distribution line; effectively brings the pipe to or above grade, facilitating periodic flushing of the lateral and enabling certain operational activities.

Amount of liquid required to fill a lateral.

Two or more distinctly different soil or rock types arranged in layers; micaceous seams or weakened planes in rock or shale are considered layered.