Dosing Septic Tank
(1)A dosing septic tank may discharge effluent with a pump or dosing siphon from the clear zone at the outlet end of the tank. These may be considered for installations where the design flow does not exceed 600 gallons per day.
(a)The minimum total primary volume of the tank must be 1,100 gallons for flows less than or equal to 450 gallons per day and 1,500 gallons for flows greater than 450 and up to 600 gallons per day.
(b)The submerged volume at the lowest operating liquid level must be at least 900 gallons. The remaining capacity must be used to ensure optimum surge capacity and reserve storage capacity.
(c)Liquid levels must be controlled in a manner that is consistent with pump dosing requirements described in OAR 340, divisions 071 and 073.
(d)All apparatus must be constructed and installed to facilitate ease of service without having to alter any other component.
(e)The installation manual described in OAR 340-073-0025 (Tank Construction)(13) must include additional information about siphon selection, installation of the pump or siphon vault and screen, pump control and alarm levels, and the watertight pass-through methods for electrical wiring and pipe.
Rule 340-073-0030 — Dosing Septic Tank,