SEPTIC INSTALLER TEST FOR WASHINGTON STATE
WOSSA PAPER 2026/2027 ACTUAL QUESTIONS WITH
VERIFIED ANSWERS
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.
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
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.
FC - ✔✔✔ ANSWER-Fecal Coliform, expressed in number of
colonies 100/ml.
Pressure Distribution Systems, Introductions (Pressure
distribution is usually used in locations where it is either
desirable or required to:) - ✔✔✔ ANSWER-6) distribute effluent
to all sand filters, mounds, all Type 1 soils, and all other soils
with less than 24 inches of vertical separation
Pressure Distribution Systems, Introductions - ✔✔✔ ANSWER-
, Pressure distribution is also appropriate for sites in aquifer
sensitive areas and for larger drainfield systems. Finally, in
certain conditions where pumping is necessary due to
elevation problems, pressure distribution can be incorporated
with only a little additional effort.
Pressure Distribution Systems:
1. Performance Standards
1.1. Intent - ✔✔✔ ANSWER-The intent of pressure distribution
is uniform distribution of effluent throughout the receiving
component.
Pressure Distribution Systems:
1. Performance Standards
1.2. Measure of Performance - ✔✔✔ ANSWER-The variation in
orifice discharge rates within any one lateral must not be
more than 10%,
Pressure Distribution Systems:
1. Performance Standards
1.2. Measure of Performance - ✔✔✔ ANSWER-The variation in
orifice discharge rates over the entire distribution system
must not be more than 15%,
Pressure Distribution Systems:
1. Performance Standards
1.2. Measure of Performance - ✔✔✔ ANSWER-The squirt height
WOSSA PAPER 2026/2027 ACTUAL QUESTIONS WITH
VERIFIED ANSWERS
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.
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
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.
FC - ✔✔✔ ANSWER-Fecal Coliform, expressed in number of
colonies 100/ml.
Pressure Distribution Systems, Introductions (Pressure
distribution is usually used in locations where it is either
desirable or required to:) - ✔✔✔ ANSWER-6) distribute effluent
to all sand filters, mounds, all Type 1 soils, and all other soils
with less than 24 inches of vertical separation
Pressure Distribution Systems, Introductions - ✔✔✔ ANSWER-
, Pressure distribution is also appropriate for sites in aquifer
sensitive areas and for larger drainfield systems. Finally, in
certain conditions where pumping is necessary due to
elevation problems, pressure distribution can be incorporated
with only a little additional effort.
Pressure Distribution Systems:
1. Performance Standards
1.1. Intent - ✔✔✔ ANSWER-The intent of pressure distribution
is uniform distribution of effluent throughout the receiving
component.
Pressure Distribution Systems:
1. Performance Standards
1.2. Measure of Performance - ✔✔✔ ANSWER-The variation in
orifice discharge rates within any one lateral must not be
more than 10%,
Pressure Distribution Systems:
1. Performance Standards
1.2. Measure of Performance - ✔✔✔ ANSWER-The variation in
orifice discharge rates over the entire distribution system
must not be more than 15%,
Pressure Distribution Systems:
1. Performance Standards
1.2. Measure of Performance - ✔✔✔ ANSWER-The squirt height
