(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 functions, including dissipating energy, directing solids, retaining solids, and drawing liquid off at a specific depth. A baffle is not an intercompartmental wall.

(4) "Cast-in-place tank" means a sewage tank specifically designed for and constructed at the location where it will be used.

(5) "Department" means the Washington state department of health.

(6) "Designer" means a person who matches site and soil characteristics with appropriate on-site sewage technology. Throughout this chapter this term applies to on-site wastewater treatment system designers licensed under chapter 18.210 RCW.

(7) "Design engineer" as used in this chapter, means a professional engineer who is experienced and qualified in the analysis and design of on-site wastewater treatment systems or wastewater treatment system components, and is either licensed in Washington in accordance with chapter 18.43 RCW or is licensed in another state and an exception specified in RCW 18.43.130 applies. If the sewage tank is considered a "significant structure," as defined in chapter 18.43 RCW, the design engineer shall be licensed as a structural engineer unless an exception specified in RCW 18.43.040 applies.

(8) "Effluent" means liquid discharged from a sewage tank or other on-site sewage system component.

(9) "Greywater" means domestic type flows from bathtubs, showers, bathroom sinks, washing machines, dishwashers, and kitchen or utility sinks. Greywater does not include flow from a toilet or urinal.

(10) "Grease interceptor tank" means a watertight tank similar in design to a septic tank receiving greywater that may contain grease, such as from food service establishments. The interceptor tank is designed and constructed to permit adequate separation of grease from the rest of the sewage prior to discharge into an approved sewage treatment and disposal or dispersal system.

(11) "Holding tank" means a sewage tank that is a component of an on-site sewage system designed to receive and temporarily store sewage from one or more facilities or dwellings for removal, dispersal, and ultimate disposal of the sewage at another location.

(12) "Holding tank sewage system" means an on-site sewage system that uses a holding tank, the services of a septic pumper, and off-site treatment and disposal of the sewage generated.

(13) "Installer" means a person approved by the local health officer to install on-site sewage systems or components, or as defined in chapter 246-272B WAC.

(14) "Local health officer" means the individual having been appointed under chapter 70.05 RCW as the health officer for the local health department, or having been appointed under chapter 70.08 RCW as the director of public health of a combined city-county health department, or his or her designee appointed by the local board of health.

(15) "On-site sewage system" means an integrated system of components, located on or nearby the property it serves, that conveys, stores, treats, 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.

(16) "Person" means any individual, corporation, company, association, society, firm, partnership, joint stock company, or any governmental agency, or the authorized agents of these entities.

(17) "Prefabricated tank" means a sewage tank that is manufactured off-site and delivered to the site for installation.

(18) "Pump tank" means a tank that contains pumping or dosing equipment.

(19) "Septage" means the mixture of solid wastes, scum, sludge, and liquids pumped from within septic tanks, pump chambers, holding tanks, and other on-site sewage system components.

(20) "Septic pumper" means a person approved by the local health officer to remove and transport sewage or septage from on-site sewage systems.

(21) "Septic tank" means a watertight treatment receptacle receiving the discharge of sewage from a building sewer or sewers; designed and constructed to permit separation of settleable and floating solids from the liquid, and detention and anaerobic digestion of the organic matter, prior to discharge of the liquid.

(22) "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.

(23) "Sewage tank" means a watertight prefabricated or cast-in-place septic tank, pump tank, holding tank, grease interceptor tank, recirculating filter tank, a tank used with a proprietary product, and any other tank used in an on-site sewage system. This term also includes tanks used in a septic tank effluent pump or vacuum collection/transmission system for an on-site sewage system.

(24) "Trash tank" means a type of sewage tank that removes material from sewage that microorganisms cannot degrade before the sewage enters a chamber where decomposition occurs.

(25) "Watertight" means liquids are prevented from entering or escaping except through designed openings such as inlets, outlets, intercompartmental wall fittings or baffles.