Two rules stack, and the difference matters. The state rule sets the inspection you must actually have done: at least every three years for a system that is just a septic tank and a gravity drain field, and every year for anything more complex, unless the Health Department requires it more often.
The Tacoma-Pierce County Health Department then assigns your system a risk classification, which sets how often the result must be reported to them: annually at high risk, every three years at moderate risk, and at low risk only when you apply for a Report of System Status, after a new system is installed, or when the Health Department asks. Gravity and pump-to-gravity systems are generally low risk; pressure distribution, mounds and sand filters are moderate; holding tanks and community systems are high. Age, repair history and drainage toward sensitive water can raise the tier, and the Health Department notifies you in writing ahead of the due date.
In Vaughn, as everywhere in Pierce County, the evaluation has to be carried out and reported by a certified operation-and-maintenance firm — there is no homeowner option. Owner-occupied gravity systems can apply to move a three-year cycle to five if they meet every condition, one of which is that the property is not on a shoreline. Selling triggers a Report of System Status.
Marine protection: what is different on the Key Peninsula
Vaughn sits on the Key Peninsula, and that changes the starting point. The Key Peninsula Marine Recovery Area — including the shellfish protection districts at Rocky Bay, Burley Lagoon and Filucy Bay — is the only Area of Special Concern the Board of Health has designated anywhere in Pierce County.
That matters because the code classifies an on-site system in an area of special concern as moderate risk, which carries a three-year reporting cycle whatever the system type. So the low-risk tier that covers an ordinary gravity system elsewhere in the county does not apply here by default, and a gravity system in Vaughn should be planned around a three-year cycle rather than the trigger-only one. Risk factors identified in the code can push a system in an area of special concern higher still.
The boundary is set by Board of Health resolution rather than by town limits, so it does not follow the Vaughn postal address exactly. Confirm your own classification with the Health Department rather than assuming it from where you live. Environmental Health Code Chapter 2, Sections 12, 38 and 39.
Sources: WAC 246-272A-0270(1)(e); Pierce County Environmental Health Code Chapter 2, Sections 34, 38, 39, 42 and 44. Operation and maintenance · Reduced inspection frequency