Decentralized Wastewater Glossary

The depth of a septic tank as measured from the invert of the outlet pipe to the bottom of the tank; see also operating volume.

See operating pressure.

Elevation of effluent in a tank under normal operating conditions; for a septic tank, operating level is located at the invert of the outlet piping; see also effective depth.

1. Design parameter described as the pressure required for a component or device to operate properly (e.g., orifices, emitters, and sprayers must have the correct pressure to produce the correct flow rate and/or spray pattern); the sum of operating pressure and elevation head constitutes the static head component of total dynamic head (TDH); 2. Operational parameter described as the pressure measurement at a predefined location; see also static head; and total dynamic head.

Amount of effluent contained in a tank under normal operating conditions; for a septic tank, operating volume is determined relative to the invert of the outlet; for a dosing tank, operating volume under normal conditions is determined relative to the invert elevation of the dosing tank inlet and the control off elevation; see also operating level.

Act of assessing the functionality of each component of the system; see also system management; inspection; maintenance; monitoring.

Specific, measurable, and enforceable standard that establishes minimum operation and maintenance frequency, evaluation parameters and reporting requirements relative to the operational status of a system; see also operation; and maintenance.

Distance between the invert of a dosing tank inlet and the control “off” elevation.

Professional who assesses process operational status, adjusts component settings to optimize treatment system function, performs root cause analysis to identify reasons for deviations from optimal system performance, conducts sampling for performance verification, and documents findings.                                       

Level consisting of a high-powered telescope with a spirit level attached to it in such a manner that when its bubble is centered, the line of sight is horizontal.

Elevation delineating the highest water level that has been maintained for a sufficient period to leave evidence upon the landscape; commonly the point where the natural vegetation changes from predominantly aquatic to predominantly terrestrial.

Substance that contains a carbon molecule in its structure.

Biodegradable fraction of chemical oxygen demand (biochemical oxygen demand, biodegradable FOG, and volatile solids) delivered to a treatment component in a specified time interval expressed as mass per time or area; e.g., pounds per day or pounds per cubic foot per day (pretreatment); pounds per square foot per day (infiltrative surface or pretreatment); typical residential system designs assume biochemical loading equals organic loading; see also biochemical oxygen demand; chemical oxygen demand; and FOG.

Material substances derived from organisms (plants or animals); containing carbon.

See trace organic contaminants.

Nitrogen bound in plant and animal matter, primarily amino acids and proteins; the amount of organic nitrogen can be obtained by separately measuring the ammonia nitrogen and subtracting that value from the total Kjeldahl nitrogen; see also Kjeldahl nitrogen and total Kjeldahl nitrogen (TKN).

Phosphorus formed primarily by biological processes; sources of organic phosphorus in sewage include bodily wastes, food residues, and the conversion of orthophosphates in biological treatment processes.

Position relative to true north to points on the compass, or to a specific place or object.

Discharge hole in a distribution system.

Part or device used to protect an orifice from external blockage.

Method of categorizing soil and rock deposits in a hierarchy of stable rock, Type A, Type B, and Type C, in decreasing order of stability; categories are determined based on an analysis of the properties and performance characteristics of the deposits and the environmental conditions of exposure; see also soil textural class.

Above-grade piping outlet designed and installed to convey high quality effluent or intercepted groundwater to the receiving environment.

See pit toilet.

Pipe tee or wall segment located at or near the outlet pipe of a septic tank and designed to collect flow from the clear zone, isolate scum from the outlet pipe, and allow ventilation.

An operating parameter under which a secondary timer with a shorter off setting activates at a designated elevation and continues to control operation until level of effluent drops below the override timer sensor off elevation; the primary timer disengages while the secondary timer is engaged. also known as “peak enable” or “amber alarm”

Onsite wastewater treatment system    

1. Chemical reaction in which a loss of electrons results in an increase in oxidation number (valence) of an element; occurs concurrently with reduction of the associated reactant; 2. Chemical or biological conversion of organic matter to simpler, more stable forms in the presence of oxygen with a concurrent release of energy; 3. process of a substance combining with oxygen.

Amount of oxygen absorbed by a liquid compared to the amount delivered into the liquid through an aeration or oxygenation device, usually expressed as the percentage equivalent; used to compare performance of aeration systems.

See disinfection, ozone.

Unstable form of oxygen (O³) used as an oxidizing, deodorizing, or bleaching agent, and sometimes used for disinfection of advanced treated effluent in an onsite wastewater treatment system; see also ozone disinfection.

Chemical process used to inactivate microorganisms via the application of ozone to wastewater; see also ozone

Device that produces ozone gas

Term commonly used to describe a modular aerobic treatment system unit serving multiple dwellings or establishments with relatively large flows (greater than 1,500 gallons per day).

See media filter.

Curved tillage implement used to disrupt a hardpan or plowman.

Pressure or gravity distribution of effluent that proportionally and simultaneously loads multiple sections of a final treatment and dispersal component.

Subunit of a device; see also device and component.

Determination of the various amounts of the different soil separates in a soil sample, usually by sedimentation, sieving, micrometry, or combinations of these methods.

Relative amounts or proportions based on size, of various inorganic separates in a sample, often expressed as mass percentages; see also ASTM C-33 and uniformity coefficient.

Process of introducing air into a treatment component or process without mechanical means; see also aeration, active.

Capable of causing disease; commonly applied to organisms that cause infectious diseases.

Organisms that cause infectious disease.

A value greater than average.

1. Operating parameter that increases the frequency of timer operation of a pump to result in effluent delivery equal to design flow rate; 2. sensor that controls the peak enable function in a time dose system; see override timer; see also redundant off and timer enable.

Highest flow occurring within a specified time (minutes, hours, days, etc.); may be further expressed as peak hourly flow, peak daily flow, peak monthly flow, peak seasonal flow, etc.

Ratio of a maximum flow to the average flow (such as maximum hourly flow or maximum daily flow to the average daily flow).                       

1. Organic soil material in which the original plant parts are recognizable; 2. Fibrous organic material that may be used in a media filter.

Media filter that uses appropriate organic fibric material (peat) as the media; typically packaged as pre-fabricated modular units of containerized media; a type of biofilter.

Opening in the wall of a container through which a pipe or electrical conduit enters.

See percolation test

See episaturation.

Measurement of the drop in water level in a boring as water moves into the surrounding soil material; although sometimes conducted during site assessment for onsite/decentralized systems (often referred to as a "perc test"), soil morphologicial evaluation is the preferred method to determine hydraulic capacity and treatment potential of a given site.

Parameter describing effectiveness of constituent removal.

Minimum criteria for component or system treatment performance (e.g., presence or concentration of a constituent in effluent) typically established by a proprietary or regulatory authority to ensure compliance with public health and environmental goals of the state or community.

Defined boundary of a soil treatment area.

subsurface drain installed around and outside of an individual soil treatment area or zone and designed to actively or passively lower the water table.

Ability of a porous medium such as soil to transmit fluids (liquids or gases).

Authorization, license, or equivalent control document issued by the appropriate regulatory authority to implement the requirements of a regulation.

Measure of the acid or base quality of water that is the negative log of the hydrogen ion concentration; the scale ranges from 1-14, with a pH of 7.0 equal to neutral, 14.0 being strongly alkaline (basic), and 1.0 being strongly acidic.

Chemical substances such as prescription or over-the-counter therapeutic drugs, fragrances, cosmetic, sunscreen agents, diagnostic agents, among others; see also trace organic contaminants.

Chemical element and nutrient essential for all life forms, occurring as orthophosphate, pyrophosphate (P2O7-4), tripolyphosphate (P3O105-), and organic phosphate forms; each of these forms, as well as their sum (total phosphorus), is expressed in terms of milligrams per liter (mg/L) elemental phosphorus; occurs in natural waters and wastewater almost solely as phosphates; excess levels of phosphorus in fresh surface waters may contribute to eutrophication.

Treatment which involves only physical means of solid-liquid separation, such as filtration, flotation, and sedimentation; chemical and biological reactions do not play an important role in physical treatment.

Treatment methods in which the application of physical forces predominates as a means for removal of wastewater constituents; includes flocculation, sedimentation, flotation, filtration, screening, mixing and gas transfer.

Instrument used to estimate hydraulic pressure in a conduit, tank, or soil by sensing the location of the free water surface.

Electrical plug configuration wherein a float switch is plugged into an outlet and a pump is plugged into the back of the float switch.

Portion of an excavation that includes the bedding, haunching and initial backfill of piping; see diagram at bedding.

Amount of effluent necessary to fill a supply line and distribution system.

Portion of an excavation where piping or other conduit is located; see diagram at bedding.

Unprocessed sand or gravel found in natural deposits; also known as bank gravel or bank run.

Self-contained waterless toilet used for disposal of non-water-carried human waste; consists of a shelter built above a pit in the ground into which human waste falls.

Drawing or diagram made by projection on a horizontal plane.

View from above; also known as bird’s-eye or aerial view.

Two-dimensional details that reflect accurate dimensions of and horizontal distances between features on a site.

Process of reviewing proposed actions and associated impacts to ensure that community values and long-term sustainability are incorporated.

Drawings showing locations and details of a system and its components, specifications, and other information as needed for bidding, staging, installation, inspection, and operation and maintenance of a system.

Moisture content at which soil can be rolled into 1/8 inch diameter wire without breaking; represents the soil moisture content above which manipulation will cause compaction or smearing; measured by ASTM Standard Test Method ASTM D4318 (2005).

1. Degree to which a soil can be molded or deformed continuously and permanently using relatively moderate pressure without appreciable volume change or rupture; 2. Soil consistence term defined under wet conditions.

Numerical difference between the liquid limit and plastic limit of a soil; measured by ASTM Standard Test Method ASTM D4318 (2005).

Soil structure descriptor for soil aggregates with horizontally oriented flat, plate-like particles.

Process in which fluid particles pass through a treatment device and are discharged in the same sequence in which they enter; the particles remain in the tank for a time equal to the theoretical detention time.

Reactor in which fluid particles pass through the tank and are discharged in the same sequence in which they enter; see also plug flow.

Media filter that utilizes polystyrene material that is randomly arranged in prefabricated modular units.

Accumulation of liquid on an infiltrative surface.

Material, usually sand or gravel, with a narrow range of particle sizes with maximum open pore space; also known as well-sorted and uniformly-graded.

Material, usually sand or gravel, with a wide range of particle sizes, with minimum open pore space; also known as well-graded.

1. Open space or interstices in rock, other earth materials or synthetic media; 2. Ratio of the open space to the total volume often described as a percentage.

See chemical toilet.

Pump in which liquid is induced to flow from the supply source through inlet piping and inlet valve; water is brought into the pump volute by a vacuum created by the withdrawal of a piston or piston like device, which, on its return, displaces a certain volume of water contained in the volute and forces it to flow through the discharge valve and piping.

Process of locating and excavating buried utilities.

Water that is safe for human consumption; presumed to meet safe drinking water standards.

Device that conveys the power from the vehicle’s main motor to the drive mechanism of an implement; e.g., the vacuum pump on a cargo tank.

Pharmaceutical and personal care products.