Terms commonly associated with septic systems: Please note: some of the following terms are generic while some are precise legal definitions in the State of Washington. Please consult specific rules and regulations of your State and/or local jurisdiction other definitions regarding these and other terms associated with septic systems. A Anaerobic wastewater process: a three step bacterial respiration process that occurs Absorption Area - an area to which in the absence of oxygen. Heterotrophic wastewater is distributed for infiltration to bacteria (which do not require oxygen) the soil. oxidize material to form CO2 and water. The process is more complex than described Absorption Field – see Drainfield. here, involving also autotrophic bacteria and chemical processes in three stages: acid fermentation, acid regression, and alkaline Absorption Trench - a long narrow area fermentation. (excavation) which includes a pipe for the distribution of septic tank effluent. B Additive or septic additive, septic chemical, septic treatment, septic tank additive: A Baffle - a flow deflecting device used in septic additive is a chemical, bacteria, or septic tanks and distribution boxes to inhibit other product sold to be placed into a septic the discharge of floating solids, reduce the tank or septic absorption system, amount of settleable solids that exit, and purportedly to improve the function of the reduce the exit velocity of the wastewater. system, improve drainfield performance, avoid septic tank pumping, or other repair Basal area – the effective surface area or maintenance need. In a normal available to transmit the treated effluent conventional septic system additives are not from the filter media in a mound system into required, are illegal in some jurisdictions, the original receiving soils. and in some cases they can actually damage the system leading to costly repairs. Biomat: a bacterial slime layer in the soil below the leachfield and around other Aerobic Treatment Unit (ATU) – a wastewater disposal systems. Critical septic container of various configurations that effluent treatment occurs in the biomat. provides for aerobic degradation or decomposition of wastewater constituents Blackwater or septage - waste carried off by bringing the wastewater into direct by toilet and urinal. contact with air by some mechanical means. BOD - Biochemical Oxygen Demand - Aggregate - washed gravel or crushed the amount of oxygen necessary to permit stone 3/4 - 1 1/2 inches in diameter. See microbes (within a septic treatment system) drain rock. to consume organic material in wastewater. BOD is normally expressed as BOD-5 or Alternative Septic System – an on-site five-day BOD, the amount of oxygen sewage system other than a conventional consumed by microbes (for example within gravity system or a conventional pressure a septic treatment systems) over a five day distribution system. Properly operated and period, for a given volume of wastewater. maintained alternative systems provide BOD is used to describe the quality of equivalent or enhanced treatment untreated wastewater, or in other words, to performance as compared to conventional determine the amount of treatment that gravity systems. wastewater will require before it can be discharged to the environment. 1 Breakout or effluent breakout: Visible concrete block or (safer) pre-cast concrete movement of septic effluent to the surface lined pit into which sewage is discharged. of a property. Septic effluent appearing on Solids remain in the pit, effluent is absorbed the surface of a property or in nearby ponds into soil below and at the sides of the or streams, is incontrovertible evidence of a cesspool. Solids settle to the bottom, failure in the septic system. Breakouts of floating grease and scum collect at the top, septic effluent may occur during normal and liquid seeps into the ground, initially system usage when the absorption bed has through the bottom and most of the time failed, when the system has been through the side of the cesspool. overloaded, or during a septic loading and dye test. Chemical Toilets: use a chemically treated reservoir located directly below the toilet Building Sewer - that part of the drainage seat. The chemicals reduce odors and system which extends from the end of the perform partial (incomplete) disinfection of building drain and conveys wastewater to the waste. the sewage system or sewer (the pipe from the house to the septic tank). Cleanout - an opening providing access to part of the sewage system. C Cluster Septic System: a type of Capacity of a Septic System: describes centralized septic system serving as few as the volume of wastewater (blackwater or two homes, or just a few homes. Clustered greywater) which an onsite septic system septic systems may be used in a must be capable of handling. Typically development of new homes in which small capacity, described as daily volume of groups of two or three homes are served by wastewater in gallons or liters, is a function individual wastewater treatment systems. of the number of building occupants using the facility, adjusted for other building Coliform (Bacteria) – a group of bacteria activities such as laundry, garbage grinders, which produce gas and ferment lactose, or other site activities. some of which are found in the intestinal tract of warm-blooded animals. They are Catabolism: the oxidative, exothermic, indicators of potential ground water and /of enzymatic degradation process resulting in surface water contamination with such fecal release of energy from large organic material. molecules. One of the processes in the breakdown of wastewater by Composting Toilets: use natural materials microorganisms. inside of a holding tank to decompose sewage where the decomposed material is Centralized Septic System: an onsite retained for later removal. wastewater disposal system which collects waste from multiple buildings or facilities for Conventional gravity system: a treatment and disposal at a single site or traditional onsite sewage system consisting facility. Centralized septic systems may of a (water-tight) septic tank and a serve an entire community or a large group subsurface absorption system with gravity of homes such as townhouses or distribution of the effluent condominiums. Centralized wastewater and septage disposal systems are generally Conventional pressure distribution associated with large treatment system – an on-site sewage system requirements such as for an entire consisting of a septic tank and a subsurface community. soil absorption system with pressure distribution of the effluent. Cesspool: A cesspool combines the septic treatment tank and absorption system into a single component. A cesspool is a stone or 2 Covenant – a recorded agreement stating containing a pump and pressure distribution certain activities and/or practices are system, the pump turns on when sufficient required or prohibited. volumes (demand) flow into the chamber causing the pump-on float to activate and Cover material – the material used to the predetermined dose volume to be cover a mound system, usually selected discharged to the treatment and /or disposal because of its availability, cost, and ability component which follows. to support vegetation, to transfer ozygen, and to shed water. It includes the cap and Denitrification: the removal of nitrogen topsoil. from wastewater, normally by an anoxic process. Cuts and/or banks – any naturally occurring or artificially formed slope greater Designer – a person licensed by the than one hundred percent (forty-five Washington State Department of Licensing degrees) and extending vertically at least to match site and soil characteristics with five feet from the toe of the slope to the top appropriate on-site sewage technology. of the slope as follows: Discharge Effluent Pipe: this pipe conducts septic effluent out of a pumping chamber (under pump power) or septic tank (by gravity). 45 o Disinfection Septic Systems for onsite wastewater treatment: some onsite 1 wastewater treatment and disposal systems 5 feet are required to disinfect the effluent before 1 it can be discharged to the environment. Sand bed systems, filter systems, and aerobic systems may require disinfection o depending on the level of treatment 45 achieved by other wastewater handling components. Dissolved oxygen (DO) – the oxygen dissolved in water, wastewater, or other Curtain Drain - a subsurface drain designed liquid, usually expressed in milligrams per and constructed to control groundwater and liter (mg/l), parts per million (ppm), or surface water intrusion into the area of the percent of saturation. sewage system. Disposal component – a subsurface D absorption system (SSAS) or other soil absorption system (for example, a mound) Decentralized wastewater treatment: receiving septic tank or other pretreatment wastewater treatment and disposal systems device effluent and transmitting into handling a small volume of effluent, but original, undisturbed soil. serving multiple buildings, usually ones which are built close together, such as a Distributing valve: A valve that distributes small apartment complex. flow to multiple drainfield laterals, zones or locations by automatically rotating upon Demand system – any system where the each pump cycle. Mechanical distributing dosing frequency (or flow to a treatment or valves may also be used. disposal component) is controlled by the volume of effluent flowing to the Distribution Box - a device used to component. For a demand system uniformly distribute