©THESTAR 2024/2025 ALL RIGHTS RESERVED 3:09PM.
Septic Installer Test For Washington State
(WOSSA) Exam Study Guide.
ANSI - Answer✔American National Standards Institute
BOD - Answer✔biochemical oxygen demand, typically expressed in mg/L.
CBOD - Answer✔Carbonaceous Biochemical Oxygen Demand, expressed in mg/L.
FC - Answer✔Fecal Coliform, expressed in number of colonies 100/ml.
LOSS - Answer✔large on-site sewage system
NSF - Answer✔Nation Sanitation Foundation International
O&G - Answer✔Oils and Grease, component of sewage typically originating from food stuffs
(animal fats of vegetable oils) expressed in mg/L.
RS&G - Answer✔Recommended Standards and Guidance
SSAS - Answer✔a subsurface soil absorption system
TAC - Answer✔Technical Advisory Committee established in WAC 247-272A-0400
TN - Answer✔Total Nitrogen, expressed in mg/L.
TSS - Answer✔Total Suspended Solids. A measure of the total suspended solids in a given
solution, expressed in mg/L.
USEPA - Answer✔United States Environmental Protection Agency
Additive - Answer✔a commercial product added to an on-site sewage system intended to affect
the performance or aesthetics of an on-site sewage system
Approved - Answer✔Acceptable to the authority having jurisdiction. Local health officer or the
department
BED - Answer✔a soil dispersal component consisting of an excavation with a width greater than
3 feet
1
, ©THESTAR 2024/2025 ALL RIGHTS RESERVED 3:09PM.
Building Sewer - Answer✔that part of the horizontal piping of a drainage system which starts
from the end of the building drain and which receives the discharge of the building drain and
conveys it to a public sewer, private sewer, individual sewage disposal system or other point of
disposal. It begins two feet outside the building wall and conveys sewage from the building
drain to the remaining portions of the on-site sewage system.
Cesspool - Answer✔a covered hole or pit for receiving drainage or sewage, as from a house
allowing liquid to seep into the surronding rock or soil
Conforming System - Answer✔an on-site sewage system of component meeting rules of: New
construction requirements
Approved and installed within previous requirements
Permitted by WAC-246-272A-0420
Cover Material - Answer✔Soil placed over dispersal component, made up of mineral material
with no greater than 10% organic content. Cover may contain organic surface material, an
organic landscaper to help reduce and contain soil erosion.
Cuts and Banks - Answer✔a naturally occurring or artificially formed slope greater than one
hundred percent (forty-five degrees) and extending vertically at least five from the toe of the
slope to top of the slope.
Department - Answer✔Washington State Department of Health
Designer - Answer✔Person who matches site and soil characteristics with approved
components
Design Flow - Answer✔Means the maximum volume of sewage a residence, structure or other
facility is estimated to generate in a twenty-four hour period. It incorporates both an operating
capacity and a surge capacity for the system during periodic heavy use events. The sizing and
design of a on-site sewage system component is based on the design flow.
Development - Answer✔The creation of a residence, structure, facility, subdivision, area, or
similar activity resulting in the production of sewage.
Disinfection - Answer✔The process of destroying pathogens in sewage through the application
of chlorination, ultra-violent light, or ozonation.
Distribution Technology - Answer✔any arrangement of equipment and/or material that
distributes sewage within and on-site sewage system.
Drainfield - Answer✔subsurface soil absorption system, and soil dispersal component
2
, ©THESTAR 2024/2025 ALL RIGHTS RESERVED 3:09PM.
Drainrock - Answer✔cleaned washed gravel or crushed rock ranging in size from 3/4" to 2.5",
and containing no more than two percent by weight passing a US No.8 sieve and no more than
one percent by weight passing through a US No. 200 Sieve.
Effluent - Answer✔liquid waste discharged to a septic tank or other on-site sewage system
Expanding Clay - Answer✔means a clay soil with the mineralogy of clay particles. Clay particles
expand when absorbing water
expansion - Answer✔a change in residence, facility or site that results in the quantity of sewage
to exceed the original design
Extremely gravely - Answer✔soils with 60% or more, but not less than 90% rock fragments by
volume.
Failure - Answer✔a condition of an on-site sewage component that threatens the public health
by inadequately treating the sewage, or creating a potential direct or indirect contact between
sewage and the public.
Fecal coliform bacteria - Answer✔bacteria found in the intestinal tracts of warm-blooded
animals that are cultured in standard tests. Generally expressed as colonies per 100 ml.
Gravely - Answer✔Soils with 15% or more, but less than 35% rock fragments by volume.
Gray Water - Answer✔Sewage from bathtubs, showers, bathroom sinks, kitchen sinks, washing
machines, and dishwashers.
Ground water - Answer✔Subsurface water in the zone of saturated soils, seasonally,
permanently, or as the result of the tides.
Holding tank sewage system - Answer✔an on-site sewage system that a holding tank with no
discharge outlet
hydraulic loading rate - Answer✔the amount of effluent applied to a given treatment step,
expressed as gallons per square foot per day, (gal./sq.ft./day)
industrial waste - Answer✔Waste from production of consumer goods, mining, agriculture and
petroleum extraction and refining
Infiltrative surface - Answer✔Surface within a treatment component or soil dispersal
component to which effluent is applied and through which effluent moves into original,
undisturbed soil or other porous treatment media.
Installer - Answer✔a person approved by the local health office to install on-site sewage
systems or components
3
, ©THESTAR 2024/2025 ALL RIGHTS RESERVED 3:09PM.
Local Health Officer - Answer✔The provincial or municipal health officer.
Maintenance - Answer✔The actions necessary to keep the on-site sewage system components
functioning as designed
Massive structure - Answer✔the condition of a soil layer in which the layer appears as a
coherent of solid mass not separated into peds of any kind
Moderated structure - Answer✔Well- formed distinct peds evident in undisturbed soil. When
disturbed, soil material parts into mixture of whole peds, broken peds, and material that is not
in peds.
Monitoring - Answer✔Periodic or continuous surveillance of on-site sewage system, which is
performed by observations and measurements, to determine if the system is functioning as
intended and if system is in need of maintenance.
On-site sewage system (OSS) - Answer✔An integrated system of components , located on or
nearby the property it serves. that conveys, stores, treats, and/or provides subsurface soil
treatment and dispersal of sewage. It consists of a collection system, a treatment component or
treatment sequence, and a soil dispersal component.
Operating capacity - Answer✔the average daily volume of sewage an OSS can treat and
disperse on a sustained basis. The operating capacity, which is lower than design flow, is an
integral part of the design and is used as an index in OSS monitoring.
Ordinary High Water Mark - Answer✔The point on the bank or shore where water is present
often enough so that the upland begins to look different from the lake or stream bed.
Ped - Answer✔a unit of soil structure such as blocks, columns, granule, plate or prism formed
by natural process
Person - Answer✔Any individual, partnership, corporation, association, government or
governmental subdivision or agency or other entity:
Planned Unit Development - Answer✔A planned combination of diverse land uses, such as
housing, recreation, and shopping, in one contained development or subdivision.
Platy structure - Answer✔Thin, flat plates of soil that lie horizontally. Usually found in
compacted soil. This type of soil will impede the vertical movement of water.
Pressure distribution - Answer✔a system of small diameter pipes equally distributing effluent
throughout a SASS. Can include a drip system
Professional Engineer - Answer✔A person who has passed the Fundamentals of Engineering
exam
4
Septic Installer Test For Washington State
(WOSSA) Exam Study Guide.
ANSI - Answer✔American National Standards Institute
BOD - Answer✔biochemical oxygen demand, typically expressed in mg/L.
CBOD - Answer✔Carbonaceous Biochemical Oxygen Demand, expressed in mg/L.
FC - Answer✔Fecal Coliform, expressed in number of colonies 100/ml.
LOSS - Answer✔large on-site sewage system
NSF - Answer✔Nation Sanitation Foundation International
O&G - Answer✔Oils and Grease, component of sewage typically originating from food stuffs
(animal fats of vegetable oils) expressed in mg/L.
RS&G - Answer✔Recommended Standards and Guidance
SSAS - Answer✔a subsurface soil absorption system
TAC - Answer✔Technical Advisory Committee established in WAC 247-272A-0400
TN - Answer✔Total Nitrogen, expressed in mg/L.
TSS - Answer✔Total Suspended Solids. A measure of the total suspended solids in a given
solution, expressed in mg/L.
USEPA - Answer✔United States Environmental Protection Agency
Additive - Answer✔a commercial product added to an on-site sewage system intended to affect
the performance or aesthetics of an on-site sewage system
Approved - Answer✔Acceptable to the authority having jurisdiction. Local health officer or the
department
BED - Answer✔a soil dispersal component consisting of an excavation with a width greater than
3 feet
1
, ©THESTAR 2024/2025 ALL RIGHTS RESERVED 3:09PM.
Building Sewer - Answer✔that part of the horizontal piping of a drainage system which starts
from the end of the building drain and which receives the discharge of the building drain and
conveys it to a public sewer, private sewer, individual sewage disposal system or other point of
disposal. It begins two feet outside the building wall and conveys sewage from the building
drain to the remaining portions of the on-site sewage system.
Cesspool - Answer✔a covered hole or pit for receiving drainage or sewage, as from a house
allowing liquid to seep into the surronding rock or soil
Conforming System - Answer✔an on-site sewage system of component meeting rules of: New
construction requirements
Approved and installed within previous requirements
Permitted by WAC-246-272A-0420
Cover Material - Answer✔Soil placed over dispersal component, made up of mineral material
with no greater than 10% organic content. Cover may contain organic surface material, an
organic landscaper to help reduce and contain soil erosion.
Cuts and Banks - Answer✔a naturally occurring or artificially formed slope greater than one
hundred percent (forty-five degrees) and extending vertically at least five from the toe of the
slope to top of the slope.
Department - Answer✔Washington State Department of Health
Designer - Answer✔Person who matches site and soil characteristics with approved
components
Design Flow - Answer✔Means the maximum volume of sewage a residence, structure or other
facility is estimated to generate in a twenty-four hour period. It incorporates both an operating
capacity and a surge capacity for the system during periodic heavy use events. The sizing and
design of a on-site sewage system component is based on the design flow.
Development - Answer✔The creation of a residence, structure, facility, subdivision, area, or
similar activity resulting in the production of sewage.
Disinfection - Answer✔The process of destroying pathogens in sewage through the application
of chlorination, ultra-violent light, or ozonation.
Distribution Technology - Answer✔any arrangement of equipment and/or material that
distributes sewage within and on-site sewage system.
Drainfield - Answer✔subsurface soil absorption system, and soil dispersal component
2
, ©THESTAR 2024/2025 ALL RIGHTS RESERVED 3:09PM.
Drainrock - Answer✔cleaned washed gravel or crushed rock ranging in size from 3/4" to 2.5",
and containing no more than two percent by weight passing a US No.8 sieve and no more than
one percent by weight passing through a US No. 200 Sieve.
Effluent - Answer✔liquid waste discharged to a septic tank or other on-site sewage system
Expanding Clay - Answer✔means a clay soil with the mineralogy of clay particles. Clay particles
expand when absorbing water
expansion - Answer✔a change in residence, facility or site that results in the quantity of sewage
to exceed the original design
Extremely gravely - Answer✔soils with 60% or more, but not less than 90% rock fragments by
volume.
Failure - Answer✔a condition of an on-site sewage component that threatens the public health
by inadequately treating the sewage, or creating a potential direct or indirect contact between
sewage and the public.
Fecal coliform bacteria - Answer✔bacteria found in the intestinal tracts of warm-blooded
animals that are cultured in standard tests. Generally expressed as colonies per 100 ml.
Gravely - Answer✔Soils with 15% or more, but less than 35% rock fragments by volume.
Gray Water - Answer✔Sewage from bathtubs, showers, bathroom sinks, kitchen sinks, washing
machines, and dishwashers.
Ground water - Answer✔Subsurface water in the zone of saturated soils, seasonally,
permanently, or as the result of the tides.
Holding tank sewage system - Answer✔an on-site sewage system that a holding tank with no
discharge outlet
hydraulic loading rate - Answer✔the amount of effluent applied to a given treatment step,
expressed as gallons per square foot per day, (gal./sq.ft./day)
industrial waste - Answer✔Waste from production of consumer goods, mining, agriculture and
petroleum extraction and refining
Infiltrative surface - Answer✔Surface within a treatment component or soil dispersal
component to which effluent is applied and through which effluent moves into original,
undisturbed soil or other porous treatment media.
Installer - Answer✔a person approved by the local health office to install on-site sewage
systems or components
3
, ©THESTAR 2024/2025 ALL RIGHTS RESERVED 3:09PM.
Local Health Officer - Answer✔The provincial or municipal health officer.
Maintenance - Answer✔The actions necessary to keep the on-site sewage system components
functioning as designed
Massive structure - Answer✔the condition of a soil layer in which the layer appears as a
coherent of solid mass not separated into peds of any kind
Moderated structure - Answer✔Well- formed distinct peds evident in undisturbed soil. When
disturbed, soil material parts into mixture of whole peds, broken peds, and material that is not
in peds.
Monitoring - Answer✔Periodic or continuous surveillance of on-site sewage system, which is
performed by observations and measurements, to determine if the system is functioning as
intended and if system is in need of maintenance.
On-site sewage system (OSS) - Answer✔An integrated system of components , located on or
nearby the property it serves. that conveys, stores, treats, and/or provides subsurface soil
treatment and dispersal of sewage. It consists of a collection system, a treatment component or
treatment sequence, and a soil dispersal component.
Operating capacity - Answer✔the average daily volume of sewage an OSS can treat and
disperse on a sustained basis. The operating capacity, which is lower than design flow, is an
integral part of the design and is used as an index in OSS monitoring.
Ordinary High Water Mark - Answer✔The point on the bank or shore where water is present
often enough so that the upland begins to look different from the lake or stream bed.
Ped - Answer✔a unit of soil structure such as blocks, columns, granule, plate or prism formed
by natural process
Person - Answer✔Any individual, partnership, corporation, association, government or
governmental subdivision or agency or other entity:
Planned Unit Development - Answer✔A planned combination of diverse land uses, such as
housing, recreation, and shopping, in one contained development or subdivision.
Platy structure - Answer✔Thin, flat plates of soil that lie horizontally. Usually found in
compacted soil. This type of soil will impede the vertical movement of water.
Pressure distribution - Answer✔a system of small diameter pipes equally distributing effluent
throughout a SASS. Can include a drip system
Professional Engineer - Answer✔A person who has passed the Fundamentals of Engineering
exam
4
