Decentralized Wastewater Glossary

Staking out the system on the site, including staging areas required for completion of the project.

See soil treatment area.

See seepage pit.

1. Instrument for observing levels, having a sighting device (usually telescopic) and capable of being made precisely horizontal; also called a surveyor’s level; 2. Observation made with such an instrument.

Pole marked with a gradation facilitating the determination of a relative elevation for a point, typically constructed of wood and graduated in feet and tenths and hundredths of a foot; also known as a stadia rod.

Granting of licenses especially to practice a profession; the state of being licensed.

Total cost of a system over its design period including capital costs and ongoing operation and maintenance costs; expressed as a total present value or a monthly value over the expected life; costs in future years are discounted to the present.

Structure containing relatively large pumps and associated piping, valves, and other mechanical and electrical equipment for pumping liquid.

Line drawn on a plan that differentiates between the construction, clearing and traffic area required for the completion of an installation and the area that is to be left as found; the area is delineated on the site using a silt fence or haybales that prevent the transportation of any fines outside the construction area because of surface runoff.

Soil or site characteristic that reduces efficacy of soil treatment and thus restricts design options for a system; typically defined from a regulatory standpoint.

See restrictive layer.

Straight line passing through the center of the barrel of a telescope used in surveying; always parallel to the datum.

Quantity of liquid applied along the length of a lateral, trench or bed, typically expressed as volume per unit length (e.g. gallons per foot).

Quantity of liquid applied along the length of a lateral, trench or bed in a time interval, typically expressed as volume per unit length per unit time (e.g. gallons per foot per day).

Landscape form or feature that is narrow and elongated; the slope is uniform as one travels downslope.

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

Impermeable synthetic or natural material used to prevent or restrict infiltration and/or exfiltration.

The biological transformation of suspended volatile organic carbon into dissolved compounds available for oxidation.

See tank capacity.

Moisture content at which soil becomes unstable and will flow; measured by American Society of Testing and Materials Standard Test Method ASTM D4318 (2005).

Device that allows monitoring of the liquid level in a cargo tank.

Volume or mass of a constituent applied to a component linear length, surface area, or volumetric capacity during a specific time interval; mass units typically expressed as mass per component length (pounds per linear foot per unit time), mass per surface area (pounds per square foot per unit time) or mass per component capacity (pounds per cubic foot per unit time); volumetric units typically expressed as volume per component length (gallons per linear foot per unit time), volume per surface area (gallons per square foot per unit time) or volume per component capacity (gallons per cubic foot per unit time).

The reduction in the relative concentration of infective pathogens or surrogate parameters through a treatment process expressed in log10                     units. For example, a 1-log reduction equates to 90% removal, 2-log reduction to 99% removal, and 3-log reduction to 99.9% removal

Design parameter expressing the rate that effluent enters the infiltrative surface of the soil treatment area at equilibrium, measured in volume per area per time, e.g. gallons per square foot per day (g/ft2/day).

Configuration in which the supply line connects to the manifold and a return line is installed to create a complete connection; used in drip distribution.

See centrifugal pump.

Application of effluent over an infiltrative surface via pressurized orifices and associated devices and parts (including pump, filters, controls, and piping).                     

Distribution via a network of small diameter laterals (typically 1 ¼-inch) with small orifices (typically 1/8- to 3/16-inch) installed in a soil treatment area; also called low-pressure pipe (LPP) distribution.

See pressure-dosed

See low-pressure distribution.

See low-pressure distribution STA.

See long-term acceptance rate.

Supply line in a spray dispersal system between a pump discharge assembly and a distribution device.

Routine or periodic action taken to ensure proper system performance and extend system longevity.

See management entity; and responsible management entity.

Condition in which a component or system does not perform as designed/installed; see also hard malfunction; and soft malfunction.

Person or organization that administers a set of activities associated with system management (e.g., the owner, homeowners’ association, contracted management service); the owner is ultimately responsible; see also system management, responsible management entity; and management program.

Computer-based system capable of capturing, storing, analyzing, and displaying specifically referenced information.

Comprehensive, life-cycle series of elements and activities that address issues critical to wastewater treatment systems including the following activities: planning, siting, design, permitting, installation, inspection, operation, monitoring, maintenance, and replacement; residuals management; education, training, certification, and licensing; technology verification, certification and accreditation; corrective action and enforcement; as well as recordkeeping, inventorying, reporting, financial assistance, and funding.

Provision of one or more activities required to ensure that the wastewater treatment performance requirements established by the regulatory authority are achieved; may include planning, design, permitting, inspection, construction/installation, operation, maintenance, monitoring, enforcement, etc.; ideally, management services are provided by properly trained personnel and tracked by means of a management information system; see also management information system.

Opening in a component (such as a grease trap) or a collection system through which physical access is gained for service; incorporates a cover that can be secured.

Piping network having several outlets or inlets through which a liquid or gas is distributed or collected.

Prominent or conspicuous part or characteristic of a site that is created by humans.

Component provided to the contractor in an operable condition ready for final plumbing and/or electrical connections at the site; see also contractor-assembled.

Main portal for human entry into a cargo tank; access is usually at the highest point in the tank shell.

Quantity of organic and inorganic effluent constituents delivered to a treatment component in a time interval, expressed as mass per time.

Soil structure descriptor indicating a lack of distinct soil aggregates; material is a coherent mass {not necessarily cemented}, no secondary pores.

Tar-like (asphalt or bituminous) material used to establish a watertight seal between parts of a device or component, such as between a septic tank and access riser, between riser sections or between the tank and lid.

Acronym for a membrane bioreactor.

Tidal datum described by the average of all the high-water heights observed over the national tidal datum epoch (the specific 19-year period adopted by the national ocean service as the official time segment over which tide observations are taken and reduced to obtain mean values for tidal data).

Tidal datum described as the arithmetic mean of hourly heights observed over the National Tidal Datum Epoch.

Tidal datum described as the arithmetic mean of mean high water and mean low water; half-tide level.

See daily flow; and average daily flow.

Process of introducing air into a treatment component or process by physical agitation using a device such as a paddle, paddle wheel, spray nozzle or turbine.

Solid material that can be described by shape, dimensions, surface area, void space, and application.

Device that uses materials of varying shape, size and substance that support biofilm development designed to treat effluent by reducing BOD and/or removing suspended solids in an unsaturated environment; biological treatment is facilitated via microbial growth on the surface of the media.

Generic suspended growth configuration (combined aeration and clarification in a suspended growth reactor) which incorporates a ceramic membrane to extract clarified effluent using a centrifugal pump or, more commonly, a vacuum pump.

Bacteria which grow best at temperatures between 20- and 50-degrees C (68- and 122-degrees F) with optimum growth between 25- and 40-degrees C (77- and 104-degrees F).

Use chemical processes to convert food into energy, new growth and waste products.

Conversion of acetic acid, hydrogen gas and carbon dioxide to methane.

Bubble of less than 0.2 mm diameter generated by an air diffuser.

Biological transformation of organic nitrogen into other inorganic forms that can become part of additional biologically driven treatment processes.

Design parameter that specifies the smallest amount of effluent to be delivered to a component during a dosing event.

1. Distance from the bottom of a dosing tank to pump off elevation; coincides with the minimum volume required to maintain pump submergence; 2. Elevation at which a siphon completes a dose.

Smallest amount of effluent in a dosing tank (with either demand or time dosing) required to maintain pump submergence.

Correcting system malfunction accomplished through an operational evaluation of all components (source, collection and storage, advanced treatment, final treatment, and dispersal) to determine the reason for the malfunction.

Suspended mixture of activated sludge, dissolved gasses (e.g. DO) and wastewater undergoing treatment in the activated-sludge process; energy is required to maintain the condition.

Concentration of suspended solids in mixed liquor, expressed in milligrams per liter (mg/L); see also solids, suspended.

Fraction of the suspended solids in activated sludge mixed liquor that can be driven off by combustion at 550 degrees Celsius; indicates the concentration of microorganisms available for biological oxidation; see also solids, suspended.

Above-grade integrated treatment and dispersal system designed and installed with greater than 0 and less than 12 inches of clean sand (ASTM C-33) between the bottom of the infiltrative surface and the original ground elevation; utilizes pressure distribution; a final cover of suitable soil material stabilizes the surface and supports vegetative growth.

Condition in which a soil looks and feels damp; moist, cohesive soil can easily be shaped into a ball and rolled into small diameter threads before crumbling. moist granular soil that contains some cohesive material will exhibit signs of cohesion between particles.

Assessing component or system status relative to specific operational, performance or compliance standards (e.g., process monitoring, qualitative or quantitative monitoring as part of service visit); see also, process monitoring.

Well constructed for the purpose of determining groundwater level or constituents.

Permanent surveyor’s benchmark.

Estimate of the density of microorganisms in a sample based on certain growth rates and statistical formulas, commonly used for coliform bacteria.

See soil mottles

Above-grade integrated treatment and dispersal system designed and installed with at least 12 inches of clean sand (ASTM C-33) between the bottom of the infiltrative surface and the original ground elevation; utilizes pressure distribution; a final cover of suitable soil material stabilizes the surface and supports vegetative growth.

Most probable number.

Centrifugal pump with multiple, small diameter impellers in series within a casing that enables the liquid to be delivered at a relatively high pressure; see also centrifugal pump.

Color designation system that specifies the relative degrees of the three variables of color: hue, value, and chroma; for example: 10yr 6/4 is the color called ‘strong brown’ with a hue = 10yr, value = 6, and chroma = 4; part of the classification system is commonly used to specify soil color; see also chroma; hue; and value.

Prominent or conspicuous part or characteristic of a site that is not created by humans.

Standard unit of measurement used in water analysis to estimate the clarity of water; a nephelometer passes light through a sample and measures the amount of light deflected (usually, that light deflected at a 90-degree angle).

Stable oxidized form of nitrogen; nitrifying bacteria can convert nitrite (NO₂^-) to nitrate (NO₃^-) in the nitrogen cycle.

Biological oxidation of ammonium (NH₄⁺) to nitrite (NO₂^-) and nitrate (NO₃^-), or a biologically induced increase in the oxidation state of nitrogen.

See trench.

Unstable oxidized form of nitrogen.

Essential chemical element and nutrient for all life forms; molecular formula (N₂), constitutes 78 percent of the atmosphere by volume; nitrogen is present in surface water and groundwater as ammonia (NH₃), nitrite (NO₂^-), nitrate (NO₃^-), and organic nitrogen; excess levels of nitrogen in marine areas may contribute to eutrophication; see also ammonia nitrogen, ammonium nitrogen, nitratte nitrogen, nitrate; nitrite nitrogen and organic nitrogen.

Quantitative measure of the amount of oxygen required for the biological oxidation of nitrogenous material (such as ammonia nitrogen and organic nitrogen) in wastewater; typically measured after the carbonaceous oxygen demand has been satisfied; nitrification fraction of the BOD₅             test; see also five-day biochemical oxygen demand; carbonaceous biochemical oxygen demand; and nitrification.

Emitter that discharges effluent at rates dependent upon operating pressure.

Consists of granular materials like sand and gravel that do not stick together and rely on friction for stability; categorized by OSHA as Type C, which is the least stable and most dangerous for excavation work.

Onsite wastewater treatment system that is not described in local regulatory code.

Water that is not known to be safe to drink because it may either contain pollutants, contaminants, minerals, or infectious agents or may contain harmful constituents due to it not being a “permitted” source of drinking water; see also potable water.

Geomorphic component of hills consisting of the projecting end of an interfluve, where contour lines form convex curves around the projecting end and lines perpendicular to the contours diverge downward. Overland flow (e.g., sheet wash) is divergent; nose slopes are comparatively drier portions of hillslopes and tend to have thinner colluvial sediments and profiles, dominated by colluvium and slope wash sediments (e.g., slope alluvium); see also head slope, side slope, free face, interfluve, crest, base slope.

National Sanitation Foundation

National Sanitation Foundation (NSF) standard applied to certain residential wastewater treatment systems having rated capacities between 400 gallons (1,514 Liters) and 1,500 gallons (5,978 Liters) per day.

National Sanitation Foundation (NSF) standard applied to certain treatment systems (such as composting toilets and similar technologies) that do not utilize a liquid saturated media as a primary means of storing or treating human excreta or human excreta mixed with other organic household materials.

National Sanitation Foundation (NSF) standard applied to filtration devices for residential gravity flow septic tanks (effluent screens).

see nephalometric turbidity unit.