Section 246-272A-0238 - Design requirements-Facilitate operation, monitoring and maintenance(1) The OSS must be designed to facilitate routine operation, monitoring, and maintenance according to the following criteria:(a) For gravity OSS: (i) Sewage tank access for maintenance and inspection at finished grade is required. The local health officer may allow access for maintenance and inspection of a sewage tank to be a maximum of six inches below finished grade provided a marker showing the location of the tank access is installed at finished grade.(ii) Each SSAS lateral must include at least one observation port installed in a representative location in order to facilitate SSAS monitoring.(b) For all other OSS, service access and monitoring ports at finished grade are required for all system components. Specific component requirements include:(i) Septic tanks must have service access maintenance holes (formerly manholes) and monitoring ports for the inlet and outlet;(ii) Surge, flow equalization or other sewage tanks must have service access maintenance holes;(iii) Other pretreatment units such as aerobic treatment units and packed-bed filters must have service access maintenance holes and monitoring ports;(iv) Pump chambers, tanks, and vaults must have service access maintenance holes;(v) Disinfection units must have service access and be installed to facilitate complete maintenance and cleaning, including an easy-access, free fall sampling port; and(vi) Soil dispersal components, excluding subsurface drip, must have monitoring ports for both distribution devices and the infiltrative surface.(c) For systems using pumps, clearly accessible controls and warning devices are required including: (i) Process controls such as floats, pressure activated pump on/off switches, and pumprun timers;(ii) Diagnostic tools including dose cycle counters and hour meters on the sewage stream, or flow meters on either the water supply or sewage stream; and(iii) Audible and visual alarms designed to alert a resident of a malfunction. The alarm must be placed on a circuit independent of the pump circuit.(2) All accesses must be designed to allow for monitoring and maintenance and shall be secured to minimize injury or unauthorized access in a manner approved by the local health officer.Wash. Admin. Code § 246-272A-0238
Amended by WSR 24-06-046, Filed 3/1/2024, effective 4/1/2024Statutory Authority: RCW 43.20.050. 05-15-119, § 246-272A-0238, filed 7/18/05, effective 7/1/07.