Properly abandon or decommission a grease interceptor that is no longer in service

Steps

1. Confirm the plumbing code's abandonment provisions for exterior grease interceptors in the locally adopted edition, and obtain any required permit before beginning decommissioning work, since abandonment is generally treated as regulated plumbing work requiring a permit
2. Have the interceptor fully pumped out and cleaned of all remaining liquids and solids by a properly permitted/registered hauler before any physical decommissioning work begins
3. Per common model-code abandonment provisions, remove the interceptor's top/cover, then fill the tank completely with earth (or another code-accepted fill material), tamping thoroughly to prevent voids that could later cause surface settlement
4. Cap or properly reconnect all existing waste lines that previously fed the interceptor to the building sewer, per code and inspector direction, so no orphaned or improperly capped lines remain
5. Have the completed abandonment inspected and signed off by the local plumbing/building inspector before considering the decommissioning complete
6. Update any facility records, industrial-waste permit status, or FOG program registration with the local utility to reflect that the interceptor has been decommissioned, especially if the change results from a change of use, condemnation, or demolition