Washington Administrative Code

(1) Pressure distribution with timed dosing to the drainfield is required for all LOSS projects. A typical drainfield profile is shown in Figure 2 in this section.(2) The drainfield area must be sufficient to allow installation of the required capacity and for a reserve area calc…

(1) The design engineer shall design LOSS to facilitate operation, monitoring and maintenance. The design of cleanouts and monitoring ports must be consistent with good engineering practice and the department's recommended standards and guidance for pressure distribution systems.…

(1) The design engineer shall specify and the installer shall install only sewage tanks that comply with the requirements of chapter 246-272C WAC, On-site sewage system tanks, and this section.(2) Sewage tanks must be tested for water tightness after installation at the project s…

(1) Collection and conveyance systems and their sewer pipes, manholes, air release valves, lift stations, and other appurtenances must be designed and constructed to prevent contamination of drinking water, and protect ground and surface water, public health, and the environment …

(1) The department shall only approve treatment technologies and distribution technologies that comply with this section.(2) For public domain treatment technologies with department published recommended standards and guidance and approved specific treatment levels, the design en…

(1) Pressure distribution with timed dosing of LOSS effluent to the drainfield is required.(2) The maximum spacing between the outside laterals and the edge of the trench or bed must be one-half of the selected orifice spacing, with a variance of one-half foot or less.(3) All pre…

(1) Subsurface drip systems must have a:(a) Supply line to deliver effluent to the dripline; and(b) Return line to route filter and line flushing waste back to the primary treatment unit.(2) Where Treatment Level C or better is provided, the return line may be double-plumbed to t…

(1) Sand-lined trenches or beds may be used to meet Treatment Level B.(2) The minimum dosing frequency is:(a) Twelve equally spaced timed doses per day for coarse sand; or(b) Six equally spaced timed doses per day for ASTM C-33 sand.(3) The maximum allowable hydraulic loading rat…

(1) Intermittent sand filters may be used to meet Treatment Level B.(2) Pressure distribution to the filter media is required.(3) The minimum dosing frequency is:(a) Twelve equally spaced timed doses per day for coarse sand; or(b) Six equally spaced timed doses per day for ASTM C…

(1) A recirculating gravel filter may be used to meet Treatment Level C.(2) Pressure distribution of the effluent to the filter media is required.(3) Filter media must meet the following specifications:(a) Effective particle size between three mm and five mm; and(b) Uniformity co…

The department shall not approve a LOSS design that includes a cesspool, a drywell, or a seepage pit.[Statutory Authority: RCW 70.118B.020. WSR 11-12-035, § 246-272B-06850, filed 5/25/11, effective 7/1/11.]

(1) An owner shall not install or use a holding tank sewage system for any new residential development or expansion of residential development, except as set forth in this section.(2) The department may approve installation of holding tank sewage systems only for:(a) Permanent us…

(1) A single owner development must be managed by a public entity, a wastewater company regulated by the Washington utilities and transportation commission, or a private management entity.(2) A development where lots or units served by the LOSS are individually owned must be mana…

(1) The owner shall operate and maintain the LOSS according to:(a) The requirements in this chapter;(b) The current operating permit issued by the department, including all conditions and requirements of the operating permit; and(c) LOSS operating procedures such as those describ…

(1) The department may enter and inspect any LOSS site or LOSS facility to determine compliance with chapter 70A.115 RCW or this chapter:(a) On any weekday that is not a legal holiday between the hours of 8:00 a.m. and 5:00 p.m.; and(b) At any time with the consent of the owner o…

(1) All LOSS must provide adequate treatment in quantity and quality to sewage in a reliable manner at all times.(2) The owner shall create and implement operating procedures for normal operating conditions.(3) The owner shall create and implement operating procedures for abnorma…

(1) Owners of LOSS using mechanical treatment or lagoons with design flow greater than 14,500 gpd shall employ one or more operators certified according to chapter 173-230 WAC, Certification of operators of wastewater treatment plants.(2) Owners of LOSS with design flow greater t…

(1) The LOSS owner shall install and maintain one or more flow monitoring devices to measure flow.(2) The LOSS owner or operator shall record and report flow data in gpd as directed in the operating permit.[Statutory Authority: RCW 70.118B.020. WSR 11-12-035, § 246-272B-07250, fi…

(1) The owner, management entity, or operator shall create and follow a routine schedule as required in WAC 246-272B-04200(5) for:(a) Sewage tank inspection for septage, grease, and scum; and (b) Sewage tank pumping.(2) When removing septage, grease, scum, or sewage from a LOSS, …

(1) When an owner modifies a LOSS, the component or components being modified must meet the requirements of this chapter.(2) If the LOSS cannot meet the requirements of subsection (1) of this section, the department may consider repair or replacement of a LOSS component that is l…

(1) LOSS or LOSS component failures include, but are not limited to:(a) Sewage or partially treated sewage on the ground;(b) Sewage backing up into a connected residence or structure caused by slow soil absorption of the treated effluent or other failure;(c) Sewage or partially t…

The LOSS owner who is permanently abandoning any portion of a LOSS, including a septic tank, seepage pit, cesspool, or other sewage container, and all accessible parts of the drainfield that may become a hazard, including distribution boxes and pump chambers, shall provide:(1) Wr…

(1) The department may require the LOSS owner to connect some or all residences, structures, lots and units to a sanitary sewer system consistent with WAC 246-272B-07450 (4)(b).(2) If the local health officer or local regulations require connection to a sanitary sewer system, the…

(1) The LOSS project applicant or LOSS owner may request a waiver from specific requirements of this chapter. The request must:(a) Be in writing;(b) Identify the requirement requested to be waived;(c) State the reason for the waiver; and(d) Provide supporting information.(2) The …

(1) The department shall enforce this chapter and chapter 70A.115 RCW.(2) When any person is out of compliance with a law or rule regulating LOSS and administered by the department, the department may take appropriate enforcement actions, regardless of any prior approvals issued.…

(1) The department calculates penalties based on:(a) The significance of the violation;(b) Previous compliance record; and(c) The presence of aggravating or exacerbating circumstances.(2) Significance of violation. The department determines significance of the violation based on …

(1) The department's notice of a denial, suspension, modification, or revocation of a permit; approval; or determination to proceed must be consistent with RCW 43.70.115. An applicant or permit holder has the right to an adjudicative proceeding to contest the decision.(2) The dep…

(1) A person aggrieved by the issuance of an initial permit, or by the issuance of a subsequent permit to increase the volume of waste disposal or to change effluent characteristics, for systems with design flows of more than 14,500 gpd, has the right to an adjudicative proceedin…

If any provision of this chapter or its application to any person or circumstances is held invalid, the remainder of this chapter, or the application of the provision to other persons or circumstances is not affected.[Statutory Authority: RCW 70.118B.020. WSR 11-12-035, § 246-272…

(1) Purpose. The purpose of this chapter is to protect public health and safety by assuring proper design and construction of all tanks used in on-site sewage systems. Proper sewage tank design and construction will help prevent:(a) Surface or groundwater leaking into tanks and a…

The department shall administer this chapter under the authority and requirements of chapter 43.70 RCW. The local health officers shall administer portions of this chapter related to on-site sewage systems with design flows of less than three thousand five hundred gallons per day…

(1) This chapter applies to all prefabricated tanks and all cast-in-place tanks. This chapter establishes sewage tank design and construction requirements, plan review and approval requirements, and prefabricated tank registration requirements.(2) This chapter contains specific r…

(1) "AASHTO" means American Association of State and Highway Transportation Officials.(2) "Approved" means a written statement of acceptability issued by the department of health or the local health officer.(3) "Baffle" means a device placed in a sewage tank for multiple function…

(1) The department shall review and approve all sewage tank design and construction plans.(2) Prefabricated tank models and sizes built from approved design and construction plans must be registered with the department.(3) Cast-in-place tanks are project specific and must be cons…

(1) An applicant for sewage tank design and construction plan approval shall apply to the department by submitting a completed application in the format required by the department. For required sewage tank application information, see WAC 246-272C-0125.(2) When the department rec…

(1) Prefabricated tanks: The application for prefabricated tank design and construction approval must include the information listed in Table 1.Table 1—Required Application Information(a) Manufacturer information:(i) Manufacturer's name; (ii) Mailing address; (iii) Street address…

(1) Prefabricated tank registration expires on December 31st of the third year following initial registration.(2) The department shall create and maintain the sewage tank registered list of prefabricated tanks built from approved design and construction plans including, but not l…

(1) All prefabricated tank renewal registrations expire on December 31st of the third year of registration.(2) All prefabricated tank renewal applications must be received by the department no later than October 31st of the year the registration expires.(3) An applicant may apply…

If the department approves the design and construction plan and authorizes construction, the design engineer shall:(1) Conduct a post-construction inspection of the completed cast-in-place tank;(2) Verify all applicable requirements were satisfied;(3) Verify all excavation, backf…

(1) The design engineer shall submit calculations to the department that demonstrate the tank withstands all structural, hydraulic, hydrostatic, earth, and any anticipated traffic loads, including, but not limited to, those loads specified in WAC 246-272C-0210. The drawings must …

(1) Sewage tank loads. Sewage tanks must be designed and constructed to withstand all structural, hydraulic, hydrostatic, earth loads, and any anticipated traffic loads. They must be designed and constructed so they:(a) Do not collapse, deform, or crack when subjected to the anti…

(1) Septic tank compartments. Septic tanks must be designed and constructed with a minimum of two compartments. This standard may be met by one tank with two compartments or by two single compartment tanks in series.(a) The capacity of the first compartment must accommodate at le…

(1) Grease interceptor compartments. Grease interceptor tanks must be designed and constructed with a minimum of two compartments. This standard may be met by one tank with two compartments or by two single compartment tanks in series.(a) The capacity of the first compartment mus…

(1) A sanitary tee or baffle is required when effluent is pumped into the pump tank.(2) The sanitary tee or baffle for a pump tank must meet the following requirements:(a) The inlet sanitary tee or baffle must be installed on the inlet of the pump tank; and(b) The inlet sanitary …

(1) Trash tanks must be designed and constructed for use as a pretreatment tank or compartment.(2) Trash tank volume must not be used as part of the calculations of the required septic tank volume.[Statutory Authority: RCW 43.20.050 (2) and (3). WSR 09-23-119, § 246-272C-0245, fi…

Manufacturers shall permanently identify each sewage tank. The manufacturer shall display the following information on the top of each tank near the inlet end of the tank or inside the riser if the riser is cast in the tank:(1) Manufacturer name or logo;(2) The tank's liquid capa…

(1) The manufacturer or agent, or the design engineer may request a waiver in writing, stating the reason for the waiver.(2) The department may grant a waiver request if it is consistent with the applicable standards and intent of these rules.(3) If the department approves a waiv…

(1) The department shall enforce the provisions of this chapter.(2) When a person violates the provisions under this chapter, the department or office of the attorney general may initiate enforcement or disciplinary actions, or any other legal proceeding authorized by law includi…

(1) The department shall provide notice of the denial, suspension, modification, or revocation of a registration, certification, or approval consistent with RCW 43.70.115, chapters 34.05 RCW and 246-10 WAC.(2) A person contesting a departmental decision regarding a registration, …

If any provision of this chapter or its application to any person or circumstances is held invalid, the remainder of this chapter, or the application of the provision to other persons or circumstances shall not be affected.[Statutory Authority: RCW 43.20.050 (2) and (3). WSR 09-2…