Decentralized Wastewater Glossary

That portion of solids that is retained on a filter of 2.0 µm (or smaller) nominal pore size in a liquid, typically expressed in mg/L; to measure, a well-mixed sample is filtered through a standard glass fiber filter and the residue retained on the filter is dried to a constant weight at 103 to 105°C; the increase in the weight of the filter represents the amount of total suspended solids.

Natural or constructed elongated, sloped depressional drainage feature used to collect runoff and direct the flow to an effective outlet to prevent runon downslope; often used in conjunction with a berm;                               see also  berm.

Non-return valve in which a hinged flapper seats against an opening within a cylindrical fluid line and stops flow.

Piping and connections used to adjust the elevation of and isolate spray distribution heads from the lateral in a spray dispersal system.

Distance from two fixed points to locate a system component.

Valve used to manually or automatically direct flow from one final treatment and dispersal component to another.

Assembly of components and processes; see also treatment train.

Graphical method that describes the relationship between total dynamic head and flow in a system under operating conditions.

Complete range of activities necessary to conduct operational services on wastewater treatment systems, including inspection, operation, maintenance, monitoring, and compensation.

Information displayed in tables and charts, approved by a registered professional engineer, and used to design and construct a protective system.

Activities related to preparing to bid a system installation including reading blueprints and specifications; making notes of special details concerning the project after gathering the necessary information; and estimating the quantities of labor, materials, equipment and special items needed to complete the job.

Watertight structure or container used to hold wastewater for such purposes as aeration, equalization, holding, sedimentation, treatment, mixing, dilution, or addition of chemicals, or disinfection.

1. Regarding a septic tank, volume in gallons as measured from the bottom of the tank to the invert of the outlet piping. 2. Regarding a dosing tank, volume as measured from the bottom of the tank to the invert of the inlet.

Total volume of a tank from the inside bottom of the tank to the inside top of a tank; see also tank capacity.

Integration of telecommunications and informatics (information analytics) technology to monitor and manage assets.             

Remote communication of system status, typically incorporating an auto-dialing notification feature.            

Advanced treatment of wastewater for enhanced organic matter removal, pathogen reduction, and nutrient removal; typical standards for tertiary effluent vary according to regulatory requirements.

Type of media filter which uses non-rigid, synthetic material of varying shapes and configurations as the media; typically packaged as prefabricated modular units.

Bacteria which grow best at temperatures between 35- and 75- degrees C (95- and 167- degrees F) with optimum growth between 55- and 65- degrees C (131- and 149- F).

1. A liquid level sensing arrangement in a simplex pumping system using three float switches: a float switch assembly consisting of an on float (activation) and an off float (deactivation) for pump operation and a single differential float switch for high water alarm activation; 2. A liquid level sensing arrangement in a multiplex pumping system using three single differential float switches: a stop float switch, a lead float switch and a lag/alarm float switch for lag pump activation and high water alarm activation.

Rough pore of concrete installed on the outside of an angled fitting (tee, cross, elbow or valve) that extends back to the native soil to provide a greater bearing surface and prevent loosening of joints due to stress created in pressurized applications.

Large-scale subsurface drainage system designed for lowering groundwater for agricultural purposes.

Configuration in which a specific volume of effluent is delivered to a component based upon a prescribed interval, regardless of facility water use; see also flow equalization.

Controller for automatically starting and/or stopping a device at a given interval.

Operating parameter that allows pump operation via a specified schedule; see also peak enable and redundant off.

Operating parameter under which a sensor directly activates the pump when the effluent level reaches a preset, excessively high level; pump operation continues in essentially demand mode until the effluent drops below the override sensor off elevation; the primary timer remains engaged but does not control activation until override sensor drops out; the timer override sensor operates on a demand basis.

The hillslope position that forms a gently inclined surface at the base of a slope. Toeslopes in profile are commonly gentle and linear, and are constructional surfaces forming the lower part of a slope continuum that grades to a valley or closed depression (Hawley and Parsons, 1980). Compare summit, shoulder, backslope, footslope, valley floor.

Fixture used for defecation and urination.

Configuration in which a short manifold is installed at the higher elevation of a soil treatment area.

Plotted form of information gained through a topographic survey.

See topographic survey.

Survey made for locating objects and measuring the relief, roughness, or three-dimensional variations of the earth’s surface; detailed information is obtained pertaining to elevations as well as to the locations of man-made and natural features (buildings, roads, streams, etc.); also known as a topographic map.

Physical features of the land surface including relative elevations and geometry.

Measurement of water quality expressed as the number of colony-forming units (CFU) of coliform bacteria per unit volume; see also colony-forming unit (CFU) and heterotrophic plate count.

Measure of those solids that pass through the filter, and are then evaporated and dried at specified temperature. It should be noted that what is measured as total dissolved solids is comprised of colloidal and dissolved solids. Colloids are typically in the size range from 0.001 to 1 mm; typically expressed in mg/L.

Measure of the cumulative energy that a pump must impart to a liquid to move it from one point to another, consisting of the sum of friction head (as based upon piping diameter, system configuration, and flow rate) and static head (the sum of elevation head and operating pressure); see also friction head, static head, and operating pressure.

Measure of the residue that remains after total solids are ignited at 500 +/- 50°C; typically expressed in mg/L.

Measure of the total concentration of organic nitrogen, ammonia (NH₃), and ammonium nitrogen (NH₄⁺).

Measure of the complete nitrogen content in wastewater including nitrate (NO₃^-), nitrite (NO₂^-), ammonia (NH₃), ammonium (NH₄⁺), and organic nitrogen, expressed as mg/L of N; all these forms of nitrogen, (as well as nitrogen gas [N₂]), can be biochemically converted from one form to another and are constituents of the nitrogen cycle.

Measure of the concentration of organic carbon determined by oxidation of the organic matter into carbon dioxide (CO₂) typically expressed in mg/L.

Sum of all forms of phosphorus in effluent.

Measure of the residue remaining after a wastewater sample has been evaporated and dried at a specified temperature (103 to 105°C); includes total suspended solids (TSS) and total dissolved solids (TDS); typically expressed in mg/L.

Measure of the portion of the total solids retained on a filter with a specified pore size, measured after
being dried at a specified temperature (105°C); typically expressed in mg/L. The filter used most commonly for the determination of total suspended solids is the Whatman glass fiber filter, which has a nominal pore size of about 1.58 mm.

Measure of those solids that can be volatilized and burned off when the total solids are ignited at 500 +/- 50°C; typically expressed in mg/L.

Sudden introduction of a substance or substances that impair or destroy biological activity within a wastewater treatment process.

Organic compounds originating from residential and non-residential sources, such as ingredients in drugs, pesticides, consumer products, and industrial process agents (usually present in concentrations much lower than one mg/L) which may have adverse ecological and/or human health effects; see also pharmaceutical and personal care products.

Propulsion method using tracks, typically resulting in lesser ground pressure due to broader soil contact area; see also wheeled.

Mechanical device that converts air or water pressure to a proportional electrical current.

Local bench mark established from a referenced bench mark.

Process by which plants release water vapor to the air.

Optional first component of a wastewater treatment system, often used with a proprietary aerobic treatment unit (ATU), typically having a limited detention time, and used to remove larger items or inorganic material in the wastewater stream; trash tanks provide limited anaerobic treatment.

Method, technique, or process designed to remove solids and/or pollutants from wastewater prior to conveyance to a final treatment and dispersal component or reuse; often, this treatment is designed to meet a primary, secondary, tertiary, and/or disinfection treatment standard; includes pretreatment and advanced treatment.

Non- or slowly-degradable media used for physical, chemical, and/or biological treatment in a wastewater treatment component.

Site-specific combination of components in a specified order that constitute a wastewater treatment system; a simple example of a treatment train is a septic tank and a soil treatment area.

1. Soil treatment area (STA) configuration consisting of an excavation with a width of 3 feet or less containing distribution media and one lateral; 2. Below-grade soil treatment area consisting of one or more trenches installed in an excavation such that the bottom of the infiltrative surface is typically 18 to 36 inches below original ground elevation; utilizes pressure or gravity distribution; a cover of suitable soil stabilizes the final grade, supports vegetative growth and sheds runoff; 3. Excavation in the soil for drainage diversion; 4. Excavation for placement of piping, electrical wire or conduit; see also trench excavation.

Narrow excavation (in relation to its length) made below the surface of the ground; in general, the depth is greater than the width, but the width of a trench (measured at the bottom) is not greater than 15 feet (4.6 m). if forms or other structures are installed or constructed in an excavation so as to reduce the dimension measured from the forms or structure to the side of the excavation to 15 feet (4.6 m) or less (measured at the bottom of the excavation), the excavation is also considered to be a trench.

See shield.

See shield.

Machine that uses a chain with attached cutters to open a trench by cutting, removing, and depositing spoil to the side of the trench or onto a discharge conveyor.

Type of media filter which uses a variety of media such as rigid plastics of varying shapes, stone, or tire chips; includes a clarifier in its configuration and may include a recirculation mode.

Act of identifying and correcting the root causes of system malfunction.

Relative clarity of effluent due to the presence of varying amounts of suspended organic and inorganic materials or color.

Centrifugal pump with a curved volute that causes liquid to discharge along the centerline of the impeller;                 see also  multi-stage pump.

Temporary point on which rod readings are taken to move the leveling instrument along a survey path; a foresight (FS or +) is taken on the turning point to obtain its elevation (initially, elevation of turning point is unknown); the instrument is then moved from its position and set up at a new position beyond the turning point; a backsight (BS or +) is then taken on the turning point to determine the height of the instrument (HI); the turning point must be a firm object, such as a stone, stake, pipe, fence post, or axe head so that the elevation will not change while the instrument is being moved; if the turning point is altered while the instrument is being moved, the survey must go back to the last permanent point of known elevation (i.e., a bench mark).

A liquid level sensing arrangement in a simplex pumping system using two single differential float switches: one for pump operation (both activation and deactivation) and a second for high water alarm activation.

Enclosures constructed for either indoor or outdoor use to provide a degree of protection to personnel against access to hazardous parts; to provide a degree of protection of the equipment inside the enclosure against ingress of solid foreign objects (falling dirt and windblown dust); to provide a degree of protection with respect to harmful effects on the equipment due to the ingress of water (rain, sleet, snow, splashing water, and hose-directed water); that provides an increased level of protection against corrosion; and that will be undamaged by the external formation of ice on the enclosure.                                                                                               

OSHA soil classification that includes cohesive soils with an unconfined compressive strength of 1.5 ton per square foot (TSF) (144 kPa) or greater; examples of cohesive soils are: clay, silty clay, sandy clay, clay loam and, in some cases, silty clay loam and sandy clay loam; cemented soils such as caliche and hardpan are also considered Type A; however, no soil is Type A if: (i) the soil is fissured; or (ii) the soil is subject to vibration from heavy traffic, pile driving, or similar effects; or (iii) the soil has been previously disturbed; or (iv) the soil is part of a sloped, layered system where the layers dip into the excavation on a slope of four horizontal to one vertical (4H:1V) or greater; or (v) the material is subject to other factors that would require it to be classified as a less stable material.

OSHA soil classification that includes cohesive soil with (i) an unconfined compressive strength greater than 0.5 TSF (48 kPa) but less than 1.5 TSF (144 kPa); or (ii) granular cohesionless soils including: angular gravel (similar to crushed rock), silt, silt loam, sandy loam and, in some cases, silty clay loam and sandy clay loam. (iii) previously disturbed soils except those which would otherwise be classed as Type C soil. (iv) soil that meets the unconfined compressive strength or cementation requirements for Type A, but is fissured or subject to vibration; or (v) dry rock that is not stable; or (vi) material that is part of a sloped, layered system where the layers dip into the excavation on a slope less steep than four horizontal to one vertical (4H:1V), but only if the material would otherwise be classified as Type B.

OSHA soil classification that includes cohesive soil with (i) an unconfined compressive strength of 0.5 TSF (48 kPa) or less; or (ii) granular soils including gravel, sand, and loamy sand; or (iii) submerged soil or soil from which water is freely seeping; or (iv) Submerged rock that is not stable, or (v) material in a sloped, layered system where the layers dip into the excavation or a slope of four horizontal to one vertical (4H:1V) or steeper.

US Coast Guard approved Marine Sanitation Device that is designed to simply hold waste material for pump-out into a shore-based facility, also known as a holding tank which performs no treatment; see also holding tank.

Oxygen required to complete the oxidation, synthesis, and endogenous respiration in a sample of wastewater; see also five day biochemical oxygen demand.

Device that measures depth to liquid level by transmitting and receiving sound waves.

Light waves beyond the visible spectrum; used for disinfection of water and wastewater; see also disinfection

Physical process used to inactivate microorganisms by irradiating them with ultraviolet light (254-nm germicidal wavelength) to disrupt their metabolic activity, thus rendering them incapable of reproduction; see also ultraviolet.

Condition in which a component or system is not operating as intended, indicating a need to implement maintenance, upgrades, repairs, or further investigation; see also acceptable and malfunction.

Load per unit area at which a soil will fail in compression; determined by laboratory testing, field estimation using a pocket penetrometer, thumb penetration tests, and other methods.

Perforated pipe located below the media of a media filter; designed to collect treated effluent.

Concept of distributing effluent evenly over the surface of a component over both time and space.

Description or specification of particle size distribution calculated by dividing the diameter of particle (millimeters) of which 60% by weight is smaller, by the diameter of particle (millimeters) of which 10% by weight is smaller; expressed mathematically as D60/D10; see also particle size distribution.

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

Dispersal component with an unlined bed using evaporation, transpiration, and adsorption for dispersal of effluent with an unlined bed; sometimes called an evapotranspiration/infiltration (ETI) bed.

Movement of water in a porous soil or media that is not filled to capacity with water; the water flow is along the surface of the particles, allowing air and gases to move through the interior of the larger pore space.

Soil in which the pore spaces contain water at less than atmospheric pressure; typically, smaller pore spaces contain water because of tension and larger pore spaces contain air and other gases.

See anaerobic upflow filter.

Improving a system by adding a device or component (or replacing a given device or component with one of higher quality) to increase the system’s effectiveness or facilitate operation and maintenance.

Vertical members of a trench shoring system placed in contact with the earth and usually positioned so that individual members do not contact each other. uprights placed so that individual members are closely spaced, in contact with or interconnected to each other, are often called "sheeting."

Aqueous fluid containing urea and other materials generally exiting via the human urogenital pathway.

Toilet fixture designed to separate urine from other waste materials.

Device used to facilitate air entry during depressurization; also called an air/vacuum release valve; see also air/vacuum release valve.

Valve that serves as a type of backflow-prevention device that prevents cross-contamination by reverse flow; see also air/vacuum release valve.