Section 24.17.050 Definitions.

24.17.050 Definitions.

“Additive” means a commercial product added to an on-site sewage system intended to affect performance or aesthetics of an on-site sewage system.

“Aerobic treatment unit (ATU)” means equipment which provides enhanced aerobic biodegradation or decomposition of sewage by bringing the sewage into contact with air by some mechanical or nonmechanical means, e.g., air pumps, air injectors, fabric, grids, gravel, pipes or rotating disks.

“Alternative system” means an on-site sewage system other than a conventional gravity system. Properly operated and maintained alternative systems provide equivalent or enhanced treatment performance as compared to conventional gravity systems.

“Approved” means a written statement of acceptability based on meeting the requirements of this chapter which has been issued by the health officer or DOH.

“Bed” means a soil dispersal component consisting of an excavation with a width greater than three (3) feet.

“Bedroom” means any enclosed room that has been identified as a bedroom by the building department.

“BOD” means biochemical oxygen demand, typically expressed in mg/L.

“BOH” means the Clark County board of health.

“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 or public sewer line. It begins two (2) feet outside the building wall and conveys sewage from the building drain to the remaining portions of the on-site sewage system or public sewer system.

“CBOD5” means carbonaceous biochemical oxygen demand, typically expressed in mg/L.

“CCC” means Clark County Code.

“CCPH” means Clark County public health.

“Certified” means approved to perform on-site sewage system work by Clark County public health. Clark County public health certifies installers, operation and maintenance (O&M) specialists, and pumpers.

“Cesspool” means a pit receiving untreated sewage and allowing the liquid to seep into the surrounding soil or rock.

“Common point,” as it refers to OSS, means any interconnection of sewerage piping systems whether inside or outside of a building or structure.

“Concurrency inspection” means a site visit by CCPH to review a designer’s soil and site evaluation in order to provide a concurring or dissenting opinion as to the ability of the soil and site to support an OSS.

“Conforming system” means any on-site sewage system meeting any of the following criteria:

(a) The system is 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, previous DOH WAC or previously permitted, inspected and approved; or

“Conventional gravity system” means an on-site sewage system consisting of a septic tank and a subsurface soil absorption system with gravity distribution of the effluent within the drainfield. Includes previously described systems with a lift pump or siphon.

“Covenant” means a recorded document outlining certain activities and/or practices that are required or prohibited by a property owner.

“Cover material” means soil placed over a soil dispersal component composed predominantly of mineral material with no greater than ten (10) percent organic content. Cover material is permeable soil that may contain an organic surface layer for establishing a vegetative landscape to reduce soil erosion.

“Critical deficiencies” are structural or operational deficiencies of an OSS that are likely to result in a health hazard or imminent safety hazard, including the discharge of inadequately treated sewage to the surface or ground water.

“Cuts and/or banks” means any naturally occurring or artificially formed slope greater than one hundred (100) percent (forty-five (45) degrees) and extending vertically at least five (5) feet from the toe of the slope to the top of the slope as follows:

“Designer” means a person who matches site and soil characteristics with appropriate on-site sewage technology 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 (24) 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.

“Detailed staking” means a marking of all dimensions of a proposed dispersal system in order to ensure setback distances can be confirmed in cases where site dimensions are small.

“Development” means the creation of a residence, structure, facility, subdivision, planned unit development, site, area, or any 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.

“DOH” means the Washington State Department of Health.

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 (3/4) inch to two and one-half (2-1/2) inches, and containing no more than two (2) percent by weight passing a U.S. No. 8 sieve and no more than one (1) percent by weight passing a U.S. No. 200 sieve.

“Drywell” is an excavation more than three (3) feet deep where the sidewall of the excavation is designed to dispose of septic tank effluent. Drywells may also be called seepage pits.

“Effluent” means liquid discharged from a septic tank or other on-site sewage system component.

“Electronic reporting” means use of the database system designated by CCPH for reporting by certified pumpers and operation and maintenance specialists.

“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 an on-site sewage system to exceed its existing treatment or dispersal capability, for example, when a residence is increased from two (2) to three (3) 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 (60) percent or more but less than ninety (90) percent rock fragments by volume.

“Failure” means a condition of an on-site sewage system 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;

(d) Any cesspool;

(e) Drywell or seepage pits, where evidence of ground water or surface water quality degradation exists;

(f) Inadequately treated effluent contaminating ground water or surface water;

(g) 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 one hundred (100) ml.

“Geotextile” means barrier material covering the gravel trench or bed. The geotextile shall be nonwoven. The fabric shall be free of any chemical treatment or coating which reduces permeability and shall be inert to chemicals commonly found in soil.

“Gravelly” means soils with fifteen (15) percent or more but less than thirty-five (35) 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.

(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.”

“Health officer” means the health officer of Clark County, or a representative authorized by and under the direct supervision of the health officer as defined in Chapter 70.05 RCW.

“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 off-site treatment and disposal for the sewage generated.

“Hydraulic loading rate” means the amount of effluent applied to a given treatment step in this regulation 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 stormwater 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 qualified person certified by a health officer to install or repair on-site sewage systems or components.

“Intermediate septage holding tank” means a septage holding tank used by a certified pumper intended for intermediate storage of septage prior to final disposal at a permitted facility.

“Large on-site sewage system (LOSS)” means any on-site sewage system with design flows, at any common point, greater than three thousand five hundred (3,500) gallons per day.

“Locate” means the use of sensing and measurement devices to establish the location and dimensions of an OSS. Locates shall be performed by licensed or certified designers, engineers, installers or O&M specialists. Information shall be recorded on a designated CCPH form, and must include the following:

(a) Property identification information such as address, tax lot and property owner.

(b) Locations and dimensions of all OSS components such as tanks, distribution boxes, drainfield lines, treatment components and transport lines. Distances from one (1) or two (2) permanent reference points to components should be included.

(d) Distances of OSS components to surface water features, water wells, buildings and property lines, or other features that require setbacks to OSS components.

(e) Date of work and identity of professional who performed the locate.

“Lot” is a designated parcel, tract or area of land established by short plat, subdivision, or as otherwise permitted by Title 40, to be separately owned, leased, used, developed, or built upon.

“Maintenance” means the actions necessary to keep the on-site sewage system components functioning as designed excluding repairs or modifications for which permits are required.

“Maintenance contract” means a signed agreement between a property owner and a certified operation and maintenance specialist to provide on-site septic system maintenance.

“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.

“May” means discretionary, permissive, or allowed.

“Minor deficiency” means a deficiency with the OSS that is not likely to result in a public health hazard, but could lead to a moderate deficiency if not resolved.

“Mobile home park” means a plot of ground in which three (3) or more sites are intended for permanent occupancy by mobile homes.

“Moderate deficiency” means a deficiency with the OSS that is not likely to result in an immediate public health hazard, but could lead to a critical deficiency if not resolved.

“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.

“Modification” means substantive physical changes to an OSS such as a replacement of an OSS component or replacement of the system as a whole (formerly called voluntary replacement). A modification includes the use of “remediation technology” processes rather than a full repair to attempt to resolve a failing septic system.

“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.

“Net land area” means the area of a parcel of land enclosed within the designated boundaries minus easements, road rights-of-way, and surface waters.

“O&G” 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.

“On-site sewage system (OSS)” means an integrated system of components located on or near 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.

“O&M” refers to operation and maintenance of on-site sewage systems.

“O&M Manual” refers to a document produced by CCPH in cooperation with certified O&M specialists that outlines requirements and guidance for O&M specialists performing inspections.

“Operation and maintenance specialist” means a qualified person certified by the health officer to perform operation and maintenance inspections and repairs not requiring a permit on on-site sewage systems or components.

“Ordinary high-water mark” means the mark on lakes, streams, 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 the regulation codified in 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;

(b) The ordinary high-water mark adjoining freshwater is the line of mean high water.

“Ped” means a unit of soil structure such as a block, column, granule, plate or prism formed by natural processes.

“Permit” means a written document issued by the health officer authorizing the construction, installation, or modification of a sewage disposal system.

“Person” means any individual, corporation, company, association, society, firm, partnership, joint stock company, or any governmental agency, or the authorized agents of any such 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.

“Premises” means any building or structure and the property on which it is located and surrounding area utilized by persons as a residence, a place of business or place of sponsored public assembly and includes established picnic or camp grounds.

“Pressure distribution” means a system of small-diameter pipes equally distributing effluent throughout a SSAS, as described in the DOH “RS&G for Pressure Distribution Systems,” latest version. A subsurface drip system may be used wherever the regulation 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 Washington State Department of Ecology, DOH, and/or the health officer.

“Pumper” means a person certified by the health officer to remove and transport wastewater 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.

“Recreational vehicle” means a vehicle that is built on a single chassis; four hundred (400) square feet or less when measured at the largest horizontal projection; designed to be self-propelled or permanently towable by a light duty vehicle; and designed primarily not for use as a permanent dwelling but as temporary living quarters for recreation, camping, travel or seasonal use.

“Repair” means restoration, by reconstruction or relocation, or replacement of a failed on-site sewage system.

“Report of system status” means a CCPH operations and maintenance report filed electronically by a CCPH-certified O&M specialist completed at intervals outlined in Section 24.17.180(1)(d).

“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 (2) millimeters or more; for example, gravel, cobbles, stones, and boulders.

“RS&G” means recommended standards and guidance documents published and updated by DOH.

“Seepage pit” means an excavation more than three (3) feet deep where the sidewall of the excavation is designed to dispose of septic tank effluent. Seepage pits may also be called “drywells.”

“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 System. See “on-site sewage system” or “OSS.”

“Septic tank” means a watertight pretreatment 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.

“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. Also see “residential sewage.”

“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.

“Shall” means mandatory.

“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 a numerical classification of fine earth particles and coarse fragments as described in Section 24.17.130(2)(e), Table V.

“SSAS” means subsurface soil absorption system.

“Standard Methods” means the current 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, now or as hereafter amended, 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 current DOH “RS&G 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 regulation, 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.

“Temporary use hardship permit” allows an existing residence’s OSS to be temporarily connected to a residential mobile home on the same property subject to the conditions specified in Sections 24.17.100 and 40.240.210.

“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 (1) of six (6) levels (A, B, C, D, E and 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 (3) feet or less.

“TSS” means total suspended solids, a measure of all suspended solids in a liquid, typically expressed in mg/L.

“UGA” means an urban growth area designated in the comprehensive plan.

“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 (450) gallons of sewage per day where the proposed development is not single-family residences or a mobile home park.

“USEPA” means United States Environmental Protection Agency.

“Verification” means a complete locate of the OSS and the determination of drain field characteristics that are needed to determine the conditions and existing treatment capacity of an existing OSS as required by the health officer. Verifications must be submitted by a licensed designer or engineer.

“Vertical separation” means the depth of unsaturated, original, undisturbed soil of soil types 1 through 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 (35) percent or more but less than sixty (60) percent rock fragments by volume.

“Water table” means the upper surface of the ground water, whether permanent or seasonal. Also see “ground water.”

“WDOE” means the Washington State Department of Ecology.

“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

“Wet season” means the period of year from November 1st to May 1st. (Sec. 6 of Ord. 2007-10-01; amended by Sec. 3 of Ord. 2021-11-05)