Chapter 24.05 ON-SITE SEWAGE SYSTEM REGULATIONS

C. This chapter provides for the issuance of permits, establishment of fees, licensing and bonding of installers, pumpers, and operation and maintenance specialists of sewage disposal systems and an appeals procedure.

D. This chapter is intended to coordinate with other applicable statutes and rules for the design of on-site sewage systems under Chapter 18.210 RCW and Chapters 196-33 and 246-272A WAC.

E. This chapter is intended to coordinate with the land use planning regulation of Whatcom County. (Ord. 2006-056 Exh. A).

24.05.020 Administration.

The health officer shall administer this chapter under the authority and requirements of Chapters 70.05, 70.08, 70.46, and 43.70 RCW. Under RCW 70.05.060(7), fees may be charged for this administration. (Ord. 2006-056 Exh. A).

24.05.030 Adoption by reference.

Chapter 246-272A WAC, On-Site Sewage System Rules and Regulations, is hereby adopted by reference. If a conflict arises between Chapter 246-272A WAC and this chapter, the more restrictive regulation shall prevail. Any subsequent amendment to Chapter 246-272A WAC shall be considered to have been incorporated into this chapter without the need for further amendment. (Ord. 2006-056 Exh. A).

24.05.040 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 a container 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 or conventional pressure distribution 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 issued by the health officer or WDOH.

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

“Bedroom” means any enclosed room of 70 square feet or more that is not designated as a kitchen, living/family room, utility room, office, bathroom, or dining room adjacent to the kitchen.

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

“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.

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

“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.

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

1. In full compliance with new construction requirements under this chapter; or

2. Approved, installed and operating in accordance with requirements of previous editions of this chapter; or

3. Permitted through the waiver process which assures public health protection by higher treatment performance or other mitigation methods.

“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.

“Covenant” means a recorded agreement 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 predominately of mineral material with no greater than 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.

“Cut and/or bank” means any naturally occurring or artificially formed slope greater than 100 percent (45 degrees) and extending vertically at least five feet from the toe of the slope to the top of the slope as follows:

“Design flow” means the maximum volume of sewage a residence, structure, or other facility is estimated to generate in a 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.

“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.

“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.

Drain Field. See “Subsurface soil absorption system (SSAS)” and “Soil dispersal component.”

“Drainage ditch” means a linear excavation or depression constructed for the purpose of conveying surface runoff or ground water from one area to another.

“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 U.S. No. 8 sieve and no more than one percent by weight passing a U.S. 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:

1. Causes an on-site sewage system to exceed its existing treatment or dispersal capability; for example, when a residence is increased from two to three bedrooms or a change in use from an office to a restaurant; or

2. Results in an increase of more than 50 percent of the existing floor space; or

3. 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 60 percent or more, but less than 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:

1. Sewage on the surface of the ground;

2. Sewage backing up into a structure caused by slow soil absorption of septic tank effluent;

3. Sewage leaking from a septic tank, pump chamber, holding tank, or collection system;

4. Cesspools or seepage pits where evidence of ground water or surface water quality degradation exists;

5. Inadequately treated effluent contaminating ground water or surface water;

6. 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.

“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 15 percent or more, but less than 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:

1. Water seeping into or standing in an open excavation from the soil surrounding the excavation.

2. 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 Whatcom 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 holding tank, 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 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 qualified person approved 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 licensed 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 3,500 gallons per day.

“Lot” means the entire parcel of land with fixed boundaries in single or joint ownership, which area is for the use of the occupants of the building to be served by the proposed sewage disposal system. Easements may be included in determining the boundaries of the lot.

“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.

“May” means discretionary, permissive, or allowed.

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

“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.

“O&G” means oil and grease, a component of sewage typically originating from foodstuffs (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 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.

“Operation and maintenance specialist” means a qualified person approved by the health officer to perform operation and maintenance inspections 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:

1. The ordinary high water mark adjoining marine water is the elevation at mean higher high tide; and

2. The ordinary high water mark adjoining freshwater is the line of mean high water.

“Ped” means a unit of soil structure such as 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 alteration 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. Employees of persons holding a valid license under this chapter are included in and covered by the license and a company may designate an employee as a qualified professional representing the company.

“Planned unit development” means a development 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 campgrounds.

“Pressure distribution” means a system of small-diameter pipes equally distributing effluent throughout an SSAS, as described in the WDOH “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:

1. 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

2. Approved by or under permit from WDOE, WDOH and/or the health officer.

“Pumper” means a person approved 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 vehicular-type unit as defined by the Department of Labor and Industries, designed for temporary living quarters for recreational, camping or travel use, which either has its own motor power or is mounted on or drawn by another vehicle.

“Recreational vehicle park” means a plot of land in which three or more sites are occupied or intended for occupancy by recreational vehicles for travel, recreational or vacation uses.

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

“Report of system status” means a WCHD operations and maintenance report filed by a WCHD licensed O&M specialist completed at intervals outlined in WCC 24.05.160(A)(4).

“Reserve area” means an area of land approved for the installation of a conforming system and dedicated 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.

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

“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 System. See “On-site sewage system (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:

1. CBOD5, TSS, and O&G;

2. Other parameters that can adversely affect treatment. Examples include pH, temperature, and dissolved oxygen;

3. 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.

“Shoreline management program area” means upland areas within 200 feet of the ordinary high water mark (OHWM) of the shoreline of all streams with a mean average flow of 20 cubic feet per second, all lakes over 20 acres in size, all marine shorelines, and all associated wetlands and floodways in accordance with the Whatcom County critical areas ordinance.

“Significant periods of the year” means six months or longer.

“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 WCC 24.05.110(B)(5), Table II.

“SSAS (subsurface soil absorption system)” 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.

“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, 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 WDOH “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, 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, and N) used in these rules to:

1. Identify treatment component performance demonstrated through requirements specified in WAC 246-272A-0110; and

2. 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.

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

“Unit volume of sewage” means:

1. Flow from a single-family residence;

2. Flow from a mobile home site in a mobile home park; or

3. Four hundred fifty gallons of sewage per day where the proposed development is not single-family residences or a mobile home park.

“USEPA” means the United States Environmental Protection Agency.

“Vertical separation” means the depth of unsaturated, original, undisturbed soil of soil types one through six between the bottom infiltrative surface of a soil dispersal component and the highest seasonal water table, a restrictive layer, or soil type seven as illustrated below by the profile drawing of subsurface soil absorption systems:

“Very gravelly” means soil containing 35 percent or more, but less than 60 percent, rock fragments by volume.

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

“WCHD” means the Whatcom County health department.

“WDOE” means the Washington State Department of Ecology.

“WDOH” means the Washington State Department of Health.

“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:

1. A temporary observation or monitoring well used to determine the depth to a water table for locating an OSS;

2. An observation or monitoring well used to measure the effect of an OSS on a water table; and

3. An interceptor or curtain drain constructed to lower a water table.

“Wet season” means the period of year from December 1st to May 1st. (Ord. 2008-015 Exh. A; Ord. 2006-056 Exh. A).

24.05.050 Local management and regulation.

A. The health officer shall develop and maintain a written plan regarding development and management activities for all OSS within Whatcom County in accordance with WAC 246-272A-0015. The plan and management activities shall include:

1. Progressive development and maintenance of an inventory of all known OSS in operation within Whatcom County;

2. Identification of any areas where OSS could pose an increased public health risk;

3. Identification of operation, maintenance and monitoring requirements commensurate with risks posed by OSS within areas posing an increased public health risk;

4. Facilitating education of homeowners regarding their responsibilities to properly use and maintain their on-site sewage systems, and provide operation and maintenance information for all types of systems in use within Whatcom County;

5. Remind and encourage homeowners to complete the operation and maintenance inspections required by this chapter;

6. Maintain records required under this chapter, including of all operation and maintenance activities as identified;

7. Enforce OSS owner permit application, operation, monitoring and maintenance and failure repair requirements defined in this chapter;

8. Describe the capacity of WCHD to adequately fund the OSS plan, including the ability to find failing and unknown systems; and

9. Develop and maintain the plan to coordinate with the comprehensive land use plans within Whatcom County.

B. After being approved by the board of health following a public hearing, the health officer shall develop a written plan under subsection A of this section and shall:

1. Supply a copy of the plan to the WDOH;

2. Supply a copy of the plan to the entities responsible for land use planning and development regulations within Whatcom County; and

3. Implement the approved plan. (Ord. 2006-056 Exh. A).

24.05.060 Applicability.

A. The health officer:

1. Shall apply this chapter to OSS treating sewage and dispersing effluent from residential sewage sources with design flows up to 3,500 gallons per day;

2. May apply this chapter to OSS for nonresidential sources of sewage if treatment, siting, design, installation, and operation and maintenance measures provide treatment and effluent dispersal equal to that required of residential sources;

3. May not apply this chapter to industrial wastewater.

B. A valid sewage system design approval or construction permit issued prior to the effective date of the ordinance codified in this chapter:

1. Shall be acted upon in accordance with regulations in force at the time of issuance;

2. Shall have a maximum validity period of five years from the date of issuance or remain valid for an additional year beyond the effective date of the ordinance codified in this chapter, whichever assures the most lenient expiration date; and

3. May be modified to include additional requirements if the health officer determines that a serious threat to public health exists.

C. WDOE has authority and approval over:

1. Domestic or industrial wastewater under Chapter 173-240 WAC; and

2. Sewage systems using mechanical treatment, or lagoons, with ultimate design flows above 14,500 gallons per day.

D. WDOH has authority and approval over:

1. Systems with design flows through any common point between 3,500 to 14,500 gallons per day; and

2. Any large on-site sewage system (LOSS) for which jurisdiction has been transferred to WDOH under conditions of memorandum of agreement.

E. The health officer has authority and approval over:

1. Systems with design flows through any common point up to 3,500 gallons per day;

2. Any large on-site sewage system (LOSS) for which jurisdiction has been transferred to the WCHD from WDOH by contract.

F. Where this chapter conflicts with Chapter 90.46 RCW, Water Pollution Control, the requirements under those statutes apply. (Ord. 2006-056 Exh. A).

24.05.070 Connection to public sewer system.

A. When adequate public sewer services are available within 200 feet of the residence or facil-

ity, the health officer, upon the failure of an existing on-site sewage system, shall require hook-up to the public sewer system. The distance shall be measured along the usual or most feasible route of access.

B. The owner of a residence or other facility served by a Table VII repair, as described in WCC 24.05.170, shall abandon the OSS according to the requirements specified in WCC 24.05.190, and connect the residence or other facility to a public sewer system when:

1. Connection is deemed necessary to protect public health by the health officer;

2. An adequate public sewer becomes available within 200 feet of the residence or other facility as measured along the usual or most economically feasible route of access; and

3. The sewer utility allows the sewer connection.

C. The health officer may require a new development to connect to a public sewer system to protect public health.

D. The health officer shall require new development or a development with a failing system to connect to a public sewer system if it is required by the comprehensive land use plan or development regulations. (Ord. 2006-056 Exh. A).

24.05.080 Product development permits.

The health officer may issue a product development permit (PDP) for any single component or sequence in accordance with WAC 246-272A-0170. (Ord. 2006-056 Exh. A).

24.05.090 Permits.

A. Prior to beginning the construction process, a designer proposing the installation, repair, modification, connection to, or expansion of an OSS shall develop and submit the following to the health officer and obtain approval:

1. General information including:

a. Name and address of the property owner and the applicant at the head of each page of submission;

b. Parcel number and address, if available, of the site;

c. Source of drinking water supply;

d. Identification if the property is within the boundaries of a recognized sewer utility;

e. Size of the parcel;

f. Type of permit for which application is being made; for example, new installation, repair, expansion, alteration, or operational;

g. Source of sewage; for example, residential, restaurant, or other type of business;

h. Location of utilities;

i. Name of the designer, signature and stamp;

j. Date of application; and

k. Name and signature of the fee simple owner, the contract purchaser of the property or the owner’s authorized agent.

2. The soil and site evaluation as specified under WCC 24.05.110.

3. A detailed system design meeting the requirements under WCC 24.05.120 including:

a. A dimensional drawing showing the location of components of the proposed OSS, and the system designed for the reserve area if reserve site characteristics differ significantly from the initial area;

b. Vertical cross-section drawings showing:

i. The depth of the disposal component, the vertical separation, and depth of soil cover; and

ii. Other OSS components constructed at the site;

c. Calculations and assumptions supporting the proposed design, including:

i. Soil type;

ii. Hydraulic loading rate in the disposal component; and

iii. System’s maximum daily flow capacity.

4. Such additional information as deemed necessary by the health officer.

B. The health officer shall:

1. Issue a permit when the information submitted under subsection A of this section meets the requirements contained in this chapter;

2. Identify the permit as a new installation, repair, expansion, modification, or operational permit;

3. Include a reminder on the permit application of the applicant’s right of appeal;

4. State the period of validity and the date and conditions of renewal when requiring operational permits to be obtained and retained;

5. Specify the expiration date on the permit;

6. Respond to an application within 30 days as required in RCW 70.05.074;

7. Permit only public domain technologies that have WDOH RS&G. Permit only proprietary products that are registered by the WDOH. During the period of transition from the list of approved systems and products to the registered list, the health officer may permit products on the list of approved systems and products.

C. A permit is not required for replacement, addition, or modification of broken or malfunctioning building sewers, risers and lids, sewage tank lids, sewage tank baffles, sewage tank pumps, pump control floats, pipes connecting multiple sewage tanks, and OSS inspection boxes and ports where a sewage tank, treatment component, or soil dispersal component does not need to be replaced. The health officer may require the owner to submit information regarding these activities for recordkeeping purposes.

D. The health officer may revoke or deny a permit for just cause. Examples include, but are not limited to:

1. Construction or continued use of an OSS that threatens the public health;

2. Misrepresentation or concealment of material fact in information submitted to the health officer; or

3. Failure to meet conditions of the permit or the regulations.

E. Before the health officer issues a permit for the installation of an OSS to serve more than one unit volume of sewage, or more than one development, the applicant shall show:

1. An approved public entity owning or managing the OSS in perpetuity; or

2. A management arrangement acceptable to the health officer, recorded in covenant, lasting until the on-site system is no longer needed, and containing, but not limited to:

a. A recorded easement allowing access for construction, operation, monitoring maintenance, and repair of the OSS; and

b. Identification of an adequate financing mechanism to assure the funding of operation, maintenance, and repair of the OSS.

F. The health officer shall not delegate the authority to issue permits.

G. The health officer may stipulate additional requirements for a particular permit if necessary for public health protection.

H. The health officer shall notify any water district, sewer district or city in which the development or premises is to be located, a copy of the application for new construction or repair, provided the district or city has requested said notice. The permit shall not be issued for at least 15 calendar days in order that the district or city be given opportunity to provide public sewer services. Upon notice by the district or city that they have no objection to issuance of permit, it may be issued before the 15-day waiting period.

I. A permit shall expire three years from the date of issuance. A permit may be renewed for one year upon review by the health officer.

J. After the permit is issued, any alteration of the approved design shall be approved by the health officer in writing prior to the OSS installation. (Ord. 2006-056 Exh. A).

24.05.100 Location.

A. Persons shall design and install OSS to meet the minimum horizontal separations shown in Table I, Minimum Horizontal Separations:

Table I – Minimum Horizontal Separations
Items Requiring Setback	From Edge of Disposal Component and Reserve Area	From Sewage Tank and Distribution Box	From Building Sewer, Collection, and Nonperforated Distribution1
Nonpublic well or suction line	100 ft.	50 ft.	50 ft.
Public drinking water well	100 ft.	100 ft.	100 ft.
Public drinking water spring measured from the ordinary high water mark2	200 ft.	200 ft.	100 ft.
Spring or surface water used as drinking water source measured from the ordinary high water mark2	100 ft.	50 ft.	50 ft.
Pressurized water supply line3	10 ft.	10 ft.	10 ft.
Decommissioned well (decommissioned in accordance with Chapter 173-160 WAC)4	10 ft.	N/A	N/A
Surface water measured from the ordinary high water mark:
Marine water	100 ft.	50 ft.	10 ft.
Fresh water	100 ft.	50 ft.	10 ft.
Building foundation/in-ground swimming pool	10 ft.5	5 ft.5	2 ft.
Property or easement line5	5 ft.	5 ft.	N/A
Interceptor/curtain drains/drainage ditches:
Down-gradient6	30 ft.	5 ft.	N/A
Up-gradient6	10 ft.	N/A	N/A
Other site features that may allow effluent to surface:
Down-gradient6	30 ft.	5 ft.	N/A
Up-gradient6	10 ft.	N/A	N/A
Down-gradient cuts or banks with at least 5 ft. of original, undisturbed soil above a restrictive layer due to a structural or textural change	25 ft.	N/A	N/A
Down-gradient cuts or banks with less than 5 ft. of original, undisturbed, soil above a restrictive layer due to a structural or textural change	50 ft.	N/A	N/A
Other adjacent soil dispersal components/subsurface storm water infiltration systems	10 ft.	N/A	N/A

1. “Building sewer” as defined by the most current edition of the Uniform Plumbing Code. “Nonperforated distribution” includes pressure sewer transport lines.

2. If surface water is used as a public drinking water supply, the designer shall locate the OSS outside of the required source water protection area.

3. The health officer may approve a sewer transport line within 10 feet of a water supply line if the sewer line is constructed in accordance with Section 2.4 of WDOE’s “Criteria for Sewage Works Design,” revised October 1985, or equivalent.

4. Before any dispersal component can be placed within 100 feet of a well, the designer shall submit a “decommissioned water well report” provided by a licensed well driller, which verifies that appropriate decommissioning procedures noted in Chapter 173-160 WAC were followed. Once the well is properly decommissioned, it no longer provides a potential conduit to ground water, but septic tanks, pump chambers, containment vessels or distribution boxes should not be placed directly over the site.

5. The health officer may allow a reduced horizontal separation to not less than two feet where the property line, easement line, or building foundation is up-gradient.

6. The item is down-gradient when liquid will flow toward it upon encountering a water table or a restrictive layer. The item is up-gradient when liquid will flow away from it upon encountering a water table or restrictive layer.

B. Where any condition indicates a greater potential for contamination or pollution, the health officer may increase the minimum horizontal separations. Examples of such conditions include excessively permeable soils, unconfined aquifers, shallow or saturated soils, dug wells, and improperly abandoned wells.

C. The horizontal separation between an OSS dispersal component and an individual water well, spring, or surface water may be reduced to a minimum of 75 feet by the health officer, and be described as a “conforming” system upon signed approval by the health officer if the applicant demonstrates:

1. Adequate protective site-specific conditions, such as physical settings with low hydro-geologic susceptibility from contaminant infiltration. Examples of such conditions include evidence of confining layers and/or aquatards separating potable water from the OSS treatment zone, excessive depth to ground water, down-gradient contaminant source, or outside the zone of influence; or

2. Design and proper operation of an OSS system assuring enhanced treatment performance beyond that accomplished by meeting the vertical separation and effluent distribution requirements described in WCC 24.05.120(B), Table III; or

3. Evidence of protective conditions involving both subsections (C)(1) and (2) of this section; and

4. The well conforms to Chapter 173-160 WAC, Minimum Standards for Construction and Maintenance of Wells, if applicable.

D. Persons shall design and/or install disposal components only where:

1. The slope is less than 45 percent (24 degrees);

2. The area is not subject to:

a. Encroachment by buildings or construction such as placement of swimming pools, power poles and underground utilities;

b. Cover by impervious material;

c. Vehicular traffic; or

d. Other activities adversely affecting the soil or the performance of the OSS;

3. Sufficient reserve area for replacement exists to treat and dispose of 100 percent of the design flow;

4. The land is stable; and

5. Surface drainage is directed away from the site.

E. New OSS shall be located on the same lot as the buildings they are designed to serve, or on a separate lot if a permanent easement for access, maintenance and repair is obtained and recorded.

F. The health officer may approve a sewer transport line within 10 feet of a water supply line if the sewer line is constructed in accordance with Section C1-9 of the WDOE “Criteria for Sewage Works Design,” December 1998. (Ord. 2006-056 Exh. A).

24.05.110 Soil and site evaluation.

A. Only professional engineers, designers, or the health officer may perform soil and site evaluations. Soil scientists may only perform soil evaluations.

B. The person evaluating the soil and site shall:

1. Report:

a. A sufficient number of soil logs to evaluate conditions within:

i. The initial disposal component; and

ii. The reserve area;

b. The ground water conditions, the date of the observation, and the probable maximum height;

c. The topography of the proposed initial system, the reserve area, and those areas immediately adjacent that contain characteristics impacting the design;

d. The drainage characteristics of the proposed initial system, the reserve area and those areas immediately adjacent that contain characteristics impacting the design;

e. The existence of structurally deficient soils subject to major wind or water erosion events such as slide zones and dunes;

f. The existence of designated floodplains and other areas identified in the local management plan required in WCC 24.05.050; and

g. The location of existing features affecting system placement, such as, but not limited to:

i. Wells and suction lines;

ii. Water sources and supply lines;

iii. Surface water and storm water infiltration areas;

iv. Abandoned wells;

v. Outcrops of bedrock and restrictive layers;

vi. Buildings;

vii. Property lines and lines of easement;

viii. Interceptors such as footing drains, curtain drains and drainage ditches;

ix. Cuts, banks, and fills;

x. Driveways and parking areas;

xi. Existing OSS; and

xii. Underground utilities;

2. Use the soil and site evaluation procedures and terminology in accordance with Chapter 5 of the On-Site Wastewater Treatment Systems Manual, EPA 625/R-00/008, February 2002, or later version except where modified by, or in conflict with, this chapter;

3. Use the soil names and particle size limits of the United States Department of Agriculture Soil Conservation Service classification system;

4. Determine texture, structure, compaction and other soil characteristics that affect the treatment and water movement potential of the soil by using normal field and/or laboratory procedures such as particle size analysis; and

5. Classify the soil as in Table II, Soil Type Descriptions:

Table II – Soil Type Descriptions
Soil Type	Soil Textural Classifications
1	Gravelly and very gravelly coarse sands, all extremely gravelly soils excluding soil types 5 and 6, all soil types with greater than or equal to 90% rock fragments.
2	Coarse sands.
3	Medium sands, loamy coarse sands, loamy medium sands.
4	Fine sands, loamy fine sands, sandy loams, loams.
5	Very fine sands, loamy very fine sands; or silt loams, sandy clay loams, clay loams and silty clay loams with a moderate or strong structure (excluding platy structure).
6	Other silt loams, sandy clay loams, clay loams, silty clay loams.
7 Unsuitable for treatment or dispersal	Sandy clay, clay, silty clay, strongly cemented or firm soils, soil with a moderate or strong platy structure, any soil with a massive structure, any soil with appreciable amounts of expanding clays.

C. The owner of the property or his agent shall:

1. Prepare the soil log excavation to:

a. Allow examination of the soil profile in its original position by:

i. Excavating pits of sufficient dimensions to enable observation of soil characteristics by visual and tactile means to a depth three feet deeper than the anticipated bottom of the disposal component; or

ii. Stopping at a shallower depth if a water table or restrictive layer is encountered; and

b. Allow determination of the soil’s texture, structure, color, bulk density or compaction, water absorption capabilities or permeability, and elevation of the highest seasonal water table; and

2. Assume responsibility for constructing and maintaining the soil log excavation in a manner to reduce potential for physical injury as required by Chapter 296-155 WAC by:

a. Placing excavated soil no closer than two feet of the excavation;

b. Providing a ladder, earth ramp or steps for safe egress to a depth of four feet, then scoop out a portion from the floor to gain the additional two-foot depth necessary to observe the six feet of soil face; however, the scooped portion is not to be entered;

c. Provide a physical warning barrier around the excavation’s perimeter; and

d. Fill the excavation after the health officer has approved or denied the application.

D. The health officer:

1. Shall render a decision on the height of the water table within 12 months of receiving the application under precipitation conditions typical for the region;

2. May require water table measurements to be recorded during the wet season, if insufficient information is available to determine the highest seasonal water table;

3. May require any other soil and site information affecting location, design, or installation; and

4. May reduce the required number of soil logs for OSS serving a single-family residence if adequate soils information has previously been developed. (Ord. 2006-056 Exh. A).

24.05.120 Design.

A. On-site sewage systems may only be designed by professional engineers, licensed under Chapter 18.43 RCW or on-site sewage treatment system designers, licensed under Chapter 18.210 RCW.

B. The designer shall use the following criteria when developing a design for an OSS:

1. All the sewage from the building served is directed to the OSS;

2. Sewage tanks have been reviewed and approved by WDOH;

3. Drainage from the surface, footing drains, roof drains, and other nonsewage drains is prevented from entering the OSS and the area where the OSS and the reserve area are located;

4. The OSS is designed to treat and disperse the sewage volume as follows:

a. For single-family residences, the operating capacity is based on 45 gpd per capita with two people per bedroom. The minimum design flow per bedroom per day is the operating capacity of 90 gallons multiplied by 1.33. This results in a minimum design flow of 120 gallons per bedroom per day. A factor greater than 0.33 to account for surge capacity may be required by the health officer. The health officer may require an increase of the design flow for dwellings with anticipated greater flows, such as larger dwellings. The minimum design flow is 240 gallons per day;

b. For other facilities, the design flows noted in the On-Site Wastewater Treatment Systems Manual, EPA 625/R-00/008, February 2002, or later version. If the type of facility is not listed in the EPA design manual, design flows from one of the following documents are used: “On-Site Wastewater Treatment Systems Manual,” USEPA, EPA 625/R-00/008, February 2002, shall be used. Sewage flows from other sources of information may be used in determining system design flows if they incorporate both an operating capacity and a surge capacity;

5. The OSS is designed to address sewage quality as follows:

a. For all systems, the designer shall consider:

i. CBOD5, TSS, and O&G;

ii. Other parameters that can adversely affect treatment anywhere along the treatment sequence. Examples include pH, temperature and dissolved oxygen;

iii. The sensitivity of the site where the OSS will be installed. Examples include areas where fecal coliform constituents can result in public health concerns, such as shellfish growing areas, designated swimming areas, and other areas identified by the local management plan required in WCC 24.05.050;

iv. Nitrogen contributions. Where nitrogen has been identified as a contaminant of concern by the local management plan required in WCC 24.05.050, it shall be addressed through lot size and/or treatment.

b. When proposing the use of OSS for nonresidential sewage, the designer shall provide to the health officer:

i. Information to show the sewage is not industrial wastewater;

ii. Information to establish the sewage’s strength and identify chemicals found in the sewage that are not found in residential sewage; and

iii. A design providing treatment equal to that required of residential sewage.

c. The vertical separation to be used to establish the treatment levels and application rates. The selected vertical separation shall be used consistently throughout the design process.

d. Treatment levels:

i. Requirements for matching treatment component and method of distribution with soil conditions of the soil dispersal component are listed in Table III. The treatment levels correspond with those established for treatment components under the product performance testing requirements in WAC 246-272A-0110. The method of distribution applies to the soil dispersal component.

ii. Disinfection may not be used to achieve the fecal coliform requirements to meet:

(A) Treatment levels A or B in Type 1 soils; or

(B) Treatment level C.

Table III – Treatment Component Performance Levels and Method of Distribution1
Vertical Separation in Inches	Soil Type
Vertical Separation in Inches	1	2	3 – 6
12 < 18	A – pressure with timed dosing	B – pressure with timed dosing	B – pressure with timed dosing
> 18 < 24	B – pressure with timed dosing	B – pressure with timed dosing	B – pressure with timed dosing
> 24 < 36