Determine whether a French drain / grading scope of work triggers a land-disturbance or stormwater permit, using Seattle and Arvada, CO as concrete jurisdiction examples

Steps

1. For Seattle, reference the Stormwater Code page (seattle.gov/sdci/codes/codes-we-enforce-(a-z)/stormwater-code) and the current Stormwater Manual (effective July 1, 2026) for the applicable thresholds
2. Note Seattle's current thresholds: stormwater review is required above 5,000 sq ft of land disturbance or new-plus-replaced hard surface, and a professional-engineer-stamped plan is required at 5,000 sq ft of new-plus-replaced hard surface or 10,000 sq ft of land-disturbing activity
3. Confirm exterior footing/French drain work alone typically stays under these thresholds for a single-family retrofit, but combined regrading + drainage + hardscape scopes can cumulatively cross them
4. For Arvada, CO, reference the Site Disturbance Permit page (arvadaco.gov/367/Site-Disturbance-Permit) — the disturbance threshold there is 0.5 acre (revised up from 10,000 sq ft)
5. Submit Seattle applications through the Seattle Services Portal (cosaccela.seattle.gov); confirm Arvada's submission process directly on its Site Disturbance Permit page rather than assuming an identical portal workflow