The rule
“Gravity grease interceptors shall be pumped by a wastewater hauler at least every ninety (90) days or whenever twenty-five percent (25%) of the last chamber volume is occupied by grease and solids, whichever occurs first. If grease is observed in the sample box, the interceptor shall be pumped immediately” (Spokane County Code 8.03.5080.B.2).
Three triggers, then: the calendar, the last-chamber reading, and the sample box. The last chamber is the tell — grease that reaches it has already passed the baffles and is next out the outlet.
The method the code requires
“Pumped dry”; “sides, baffles and tees” washed down; wash water not returned (B.5). A partial pump-out that takes the cap and leaves the solids does not satisfy B.5 and leaves a tank that is back at 25% in weeks.
How often, really
We plan at 20% so you are never operating over the line between visits. The calculator estimates the days to 25% from tank size and meals; the first pump-out reading calibrates it. A director’s exception (8.03.5080.E) can extend the interval for a device shown to stay under 25% — and the records are the evidence for that.
If it is not pumped
The county may inspect, and “the cost of sewer cleaning or repair resulting from the failure to maintain a grease control device shall be billed to the owner” (8.03.5080.F). Add the fines on the fines page.
After every visit
- Record with date and time of service, volume removed, hauler name — the 8.03.5080.C items — for your three-year file
- Percent-full reading before service
- Condition of baffles, tees, lids, sample box