WAC 246-272A-0010
Definitions. (1) Acronyms used in
this chapter:
"ANSI" means American National Standards Institute.
"BOD" means biochemical oxygen demand, typically
expressed in mg/L.
"CBOD5" means carbonaceous biochemical oxygen demand,
typically expressed in mg/L.
"FC" means fecal coliform, typically expressed in number
colonies/100 ml.
"LOSS" means a large on-site sewage system (see chapter 246-272B WAC).
"NSF" means National Sanitation Foundation International.
"O&G" (formerly referred to as FOG) means oil and grease,
a component of sewage typically originating from food stuffs
(animal fats or vegetable oils) or consisting of compounds of
alcohol or glycerol with fatty acids (soaps and lotions).
Typically expressed in mg/L.
"OSS" means on-site sewage system.
"RS&G" means recommended standards and guidance.
"SSAS" means a subsurface soil absorption system.
"TAC" means the technical advisory committee established
in WAC 247-272A-0400.
"TN" means total nitrogen, typically expressed in mg/L.
"TSS" means total suspended solids, a measure of all
suspended solids in a liquid, typically expressed in mg/L.
"USEPA" means United States Environmental Protection
Agency.
(2) Definitions used in this chapter:
"Additive" means a commercial product added to an on-site
sewage system intended to affect the performance or aesthetics
of an on-site sewage system.
"Approved" means a written statement of acceptability
issued by the local health officer or the department.
"Bed" means a soil dispersal component consisting of an
excavation with a width greater than three feet.
"Building sewer" means that part of the horizontal piping
of a drainage system extending from the building drain, which
collects sewage from all the drainage pipes inside a building,
to an on-site sewage system. 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" means a pit receiving untreated sewage and
allowing the liquid to seep into the surrounding soil or rock.
"Conforming system" means any on-site sewage system or
component, meeting any of the following criteria:
(a) In full compliance with new construction requirements
under this chapter; or
(b) Approved, installed and operating in accordance with
requirements of previous editions of this chapter; or
(c) Permitted by the waiver process under WAC 246-272A-0420 that assures public health protection by higher
treatment performance or other methods.
"Cover material" means soil placed over a soil dispersal
component composed predominately of mineral material with no
greater than ten percent organic content. Cover material may
contain an organic surface layer for establishing a vegetative
landscape to reduce soil erosion.
"Cuts and/or banks" means any naturally occurring or
artificially formed slope greater than one hundred percent
(forty-five degrees) and extending vertically at least five
feet from the toe of the slope to the top of the slope as
follows:
"Department" means the Washington state department of
health.
"Designer" means a person who matches site and soil
characteristics with appropriate on-site sewage technology.
Throughout this chapter this term applies to both on-site
sewage treatment system designers licensed under chapter 18.210 RCW and professional engineers licensed under chapter 18.43 RCW.
"Design flow" 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
the on-site sewage system components are based on the design
flow.
"Development" means the creation of a residence,
structure, facility, subdivision, site, area, or similar
activity resulting in the production of sewage.
"Disinfection" means the process of destroying pathogenic
microorganisms in sewage through the application of
ultraviolet light, chlorination, or ozonation.
"Distribution technology" means any arrangement of
equipment and/or materials that distributes sewage within an
on-site sewage system.
"Drain field" see subsurface soil absorption system
(SSAS) and soil dispersal component.
"Drainrock" means clean washed gravel or crushed rock
ranging in size from three-quarters inch to two and one-half
inches, and containing no more than two percent by weight
passing a US No. 8 sieve and no more than one percent by
weight passing a US No. 200 sieve.
"Effluent" means liquid discharged from a septic tank or
other on-site sewage system component.
"Expanding clay" means a clay soil with the mineralogy of
clay particles, such as those found in the
Montmorillonite/Smectite Group, which causes the clay
particles to expand when they absorb water, closing the soil
pores, and contract when they dry out.
"Expansion" means a change in a residence, facility,
site, or use that:
(a) Causes the sewage quantity or quality to exceed the
existing design flow of the on-site system, for example, when
a residence is increased from two to three bedrooms or a
change in use from an office to a restaurant; or
(b) Reduces the treatment or dispersal capability of the
existing on-site sewage system or the reserve area, for
example, when a building is placed over a reserve area.
"Extremely gravelly" means soil with sixty percent or
more, but less than ninety percent rock fragments by volume.
"Failure" means a condition of an on-site sewage system
or component that threatens the public health by inadequately
treating sewage or by creating a potential for direct or
indirect contact between sewage and the public. Examples of
failure include:
(a) Sewage on the surface of the ground;
(b) Sewage backing up into a structure caused by slow
soil absorption of septic tank effluent;
(c) Sewage leaking from a sewage tank or collection
system;
(d) Cesspools or seepage pits where evidence of ground
water or surface water quality degradation exists;
(e) Inadequately treated effluent contaminating ground
water or surface water; or
(f) Noncompliance with standards stipulated on the
permit.
"Fecal coliform" means bacteria common to the digestive
systems of warm-blooded animals that are cultured in standard
tests. Counts of these organisms are typically used to
indicate potential contamination from sewage or to describe a
level of needed disinfection. Generally expressed as colonies
per 100 ml.
"Gravelly" means soils with fifteen percent or more, but
less than thirty-five percent rock fragments by volume.
"Gray water" means sewage from bathtubs, showers,
bathroom sinks, washing machines, dishwashers, and kitchen
sinks. It includes sewage from any source in a residence or
structure that has not come into contact with toilet wastes.
"Ground water" means subsurface water occupying the zone
of saturated soil, permanently, seasonally, or as the result
of the tides. Indications of ground water may include:
(a) Water seeping into or standing in an open excavation
from the soil surrounding the excavation or monitoring ports.
(b) Spots or blotches of different color or shades of
color interspersed with a dominant color in soil, caused by
reduction and oxidation of iron. These color patterns are
redoximorphic features, commonly referred to as mottling.
Redoximorphic features often indicate the intermittent
presence of ground water and may indicate poor aeration and
impeded drainage. Also see "water table."
"Holding tank sewage system" means an on-site sewage
system which incorporates a sewage tank without a discharge
outlet, the services of a sewage pumper/hauler, and the
offsite treatment and disposal for the sewage generated.
"Hydraulic loading rate" means the amount of effluent
applied to a given treatment step, in this chapter expressed
as gallons per square foot per day (gal/sq.ft./day).
"Industrial wastewater" means the water or liquid carried
waste from an industrial process. These wastes may result
from any process or activity of industry, manufacture, trade
or business, from the development of any natural resource, or
from animal operations such as feedlots, poultry houses, or
dairies. The term includes contaminated storm water and
leachate from solid waste facilities.
"Infiltrative surface" means the 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" means a person approved by the local health
officer to install on-site sewage systems or components.
"Local health officer" means the health officer of the
city, county, or city-county health department or district
within the state of Washington, or a representative authorized
by and under the direct supervision of the local health
officer, as defined in chapter 70.05 RCW.
"Maintenance" means the actions necessary to keep the
on-site sewage system components functioning as designed.
"Massive structure" means the condition of a soil layer
in which the layer appears as a coherent or solid mass not
separated into peds of any kind.
"Moderate structure" means well-formed distinct peds
evident in undisturbed soil. When disturbed, soil material
parts into a mixture of whole peds, broken peds, and material
that is not in peds.
"Monitoring" means periodic or continuous checking of an
on-site sewage system, which is performed by observations and
measurements, to determine if the system is functioning as
intended and if system maintenance is needed. Monitoring also
includes maintaining accurate records that document monitoring
activities.
"On-site sewage system" (OSS) means 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. An on-site sewage
system also refers to a holding tank sewage system or other
system that does not have a soil dispersal component.
"Operating capacity" means the average daily volume of
sewage an OSS can treat and disperse on a sustained basis.
The operating capacity, which is lower than the design flow,
is an integral part of the design and is used as an index in
OSS monitoring.
"Ordinary high-water mark" means the mark on lakes,
streams, springs, and tidal waters, found by examining the
beds and banks and ascertaining where the presence and action
of waters are so common and usual, and so long continued in
all ordinary years, as to mark upon the soil a character
distinct from that of the abutting upland with respect to
vegetation, as that condition exists on the effective date of
this chapter, or as it may naturally change thereafter. The
following definitions apply where the ordinary high-water mark
cannot be found:
(a) The ordinary high-water mark adjoining marine water
is the elevation at mean higher high tide; and
(b) The ordinary high-water mark adjoining freshwater is
the line of mean high water.
"Ped" means a unit of soil structure such as blocks,
column, granule, plate or prism formed by natural processes.
"Person" means any individual, corporation, company,
association, society, firm, partnership, joint stock company,
or any governmental agency, or the authorized agents of these
entities.
"Planned unit development" means a subdivision
characterized by a unified site design, clustered residential
units and/or commercial units, and areas of common open space.
"Platy structure" means soil that contains flat peds that
lie horizontally and often overlap. This type of structure
will impede the vertical movement of water.
"Pressure distribution" means a system of small diameter
pipes equally distributing effluent throughout a SSAS, as
described in the department's "Recommended Standards and
Guidance for Pressure Distribution Systems," 2001. A
subsurface drip system may be used wherever the chapter
requires pressure distribution.
"Professional engineer" means a person who is currently
licensed as an engineer under the provisions of chapter 18.43 RCW.
"Proprietary product" means a sewage treatment and
distribution technology, method, or material subject to a
patent or trademark.
"Public domain technology" means a sewage treatment and
distribution technology, method, or material not subject to a
patent or trademark.
"Public sewer system" means a sewerage system:
(a) Owned or operated by a city, town, municipal
corporation, county, or other approved ownership consisting of
a collection system and necessary trunks, pumping facilities
and a means of final treatment and disposal; and
(b) Approved by or under permit from the department of
ecology, the department of health and/or a local health
officer.
"Pumper" means a person approved by the local health
officer to remove and transport sewage or septage from on-site
sewage systems.
"Record drawing" means an accurate graphic and written
record of the location and features of the OSS that are needed
to properly monitor, operate, and maintain that system.
"Repair" means the relocation, replacement or
reconstruction of a failed on-site sewage system.
"Reserve area" means an area of land approved for the
installation of a conforming system that is protected and
maintained for replacement of the OSS upon its failure.
"Residential sewage" means sewage having the constituency
and strength typical of wastewater from domestic households.
"Restrictive layer" means a stratum impeding the vertical
movement of water, air, and growth of plant roots, such as
hardpan, claypan, fragipan, caliche, some compacted soils,
bedrock and unstructured clay soils.
"Rock fragment" means rock or mineral fragments having a
diameter of two millimeters or more; for example, gravel,
cobbles, stones, and boulders.
"Seepage pit" means an excavation more than three feet
deep where the sidewall of the excavation is designed to
dispose of septic tank effluent. Seepage pits may also be
called "dry wells."
"Septage" means the mixture of solid wastes, scum,
sludge, and liquids pumped from within septic tanks, pump
chambers, holding tanks, and other OSS components.
"Septic tank" means a watertight treatment receptacle
receiving the discharge of sewage from a building sewer or
sewers, designed and constructed to permit separation of
settleable and floating solids from the liquid, detention and
anaerobic digestion of the organic matter, prior to discharge
of the liquid.
"Septic system" see on-site sewage system or OSS.
"Sewage" means any urine, feces, and the water carrying
human wastes, including kitchen, bath, and laundry wastes from
residences, buildings, industrial establishments or other
places.
"Sewage quality" means contents in sewage that include:
(a) CBOD5, TSS, and O&G;
(b) Other parameters that can adversely affect treatment.
Examples include pH, temperature, and dissolved oxygen;
(c) Other constituents that create concerns due to
specific site sensitivity. Examples include fecal coliform
and nitrogen.
"Sewage tank" means a prefabricated or cast-in-place
septic tank, pump tank/dosing chamber, holding tank, grease
interceptor, recirculating filter tank or any other tanks as
they relate to on-site sewage systems including tanks for use
with proprietary products.
"Soil dispersal component" means a technology that
releases effluent from a treatment component into the soil for
dispersal, final treatment and recycling.
"Soil log" means a detailed description of soil
characteristics providing information on the soil's capacity
to act as an acceptable treatment and dispersal medium for
sewage.
"Soil scientist" means a person certified by the American
Society of Agronomy as a Certified Professional Soil
Scientist.
"Soil type" means one of seven numerical classifications
of fine earth particles and rock fragments as described in WAC 246-272A-0220 (2)(e).
"Standard methods" means the 20th Edition of Standard
Methods for the Examination of Water and Wastewater, prepared
and published jointly by the American Public Health
Association, the American Water Works Association and the
Water Environment Federation.
"Strong structure" means peds are distinct in undisturbed
soil. They separate cleanly when soil is disturbed, and the
soil material separates mainly into whole peds when removed.
"Subdivision" means a division of land or creation of
lots or parcels, described under chapter 58.17 RCW, including
both long and short subdivisions, planned unit developments,
and mobile home parks.
"Subsurface drip system" means an efficient pressurized
wastewater distribution system that can deliver small, precise
doses of effluent to soil surrounding the drip distribution
piping (called dripline) as described in the department's
"Recommended Standards and Guidance for Subsurface Drip
Systems."
"Subsurface soil absorption system" (SSAS) means a soil
dispersal component of trenches or beds containing either a
distribution pipe within a layer of drainrock covered with a
geotextile, or an approved gravelless distribution technology,
designed and installed in original, undisturbed, unsaturated
soil providing at least minimal vertical separation as
established in this chapter, with either gravity or pressure
distribution of the treatment component effluent.
"Surface water" means any body of water, whether fresh or
marine, flowing or contained in natural or artificial unlined
depressions for significant periods of the year, including
natural and artificial lakes, ponds, springs, rivers, streams,
swamps, marshes, irrigation canals and tidal waters.
"Timed dosing" means delivery of discrete volumes of
sewage at prescribed time intervals.
"Treatment component" means a technology that treats
sewage in preparation for further treatment and/or dispersal
into the soil environment. Some treatment components, such as
mound systems, incorporate a soil dispersal component in lieu
of separate treatment and soil dispersal components.
"Treatment level" means one of six levels (A, B, C, D, E,
& N) used in these rules to:
(a) Identify treatment component performance demonstrated
through requirements specified in WAC 246-272A-0110; and
(b) Match site conditions of vertical separation and soil
type with treatment components. Treatment levels used in
these rules are not intended to be applied as field compliance
standards. Their intended use is for establishing treatment
product performance in a product testing setting under
established protocols by qualified testing entities.
"Treatment sequence" means any series of treatment
components that discharges treated sewage to the soil
dispersal component.
"Trench" means a soil dispersal component consisting of
an excavation with a width of three feet or less.
"Unit volume of sewage" means:
(a) Flow from a single-family residence;
(b) Flow from a mobile home site in a mobile home park;
or
(c) Four hundred fifty gallons of sewage per day where
the proposed development is not single-family residences or a
mobile home park.
"Vertical separation" means the depth of unsaturated,
original, undisturbed soil of soil types 1-6 between the
bottom infiltrative surface of a soil dispersal component and
the highest seasonal water table, a restrictive layer, or soil
type 7 as illustrated below by the profile drawing of
subsurface soil absorption systems:
"Very gravelly" means soil containing thirty-five percent
or more, but less than sixty percent rock fragments by volume.
"Water table" means the upper surface of the ground
water, whether permanent or seasonal. Also see "ground
water."
"Well" means any excavation that is constructed when the
intended use of the well is for the location, diversion,
artificial recharge, observation, monitoring, dewatering or
withdrawal of ground water for agricultural, municipal,
industrial, domestic, or commercial use. Excluded are:
(a) A temporary observation or monitoring well used to
determine the depth to a water table for locating an OSS;
(b) An observation or monitoring well used to measure the
effect of an OSS on a water table; and
(c) An interceptor or curtain drain constructed to lower
a water table.
[Statutory Authority: RCW 43.20.050. 05-15-119, §
246-272A-0010, filed 7/18/05, effective 9/15/05.]
