French Drains & Drainage Systems in Carnation, WA

Drainage & French drains in Carnation: what to know

Carnation’s standards put runoff on the site that creates it. The city has no conveyance network for runoff from outside its existing tributary areas, and the standards require lot drainage to allow connection to subdivision improvements or to documented infiltration areas. A French drain is one way to meet that duty, but its outlet has to be planned from the start, not found after the trench is dug.

Infiltration facilities that serve private property may not sit in dedicated public road right-of-way unless the Public Works Director approves them, so a soakage area stays off the road edge. Roof downspouts stay in solid pipe, apart from the perforated line, so they do not flood the drain. We spread the flow where the soil can take it and mark any point that could send water onto the street, a sidewalk, or a neighbor’s frontage.

Permits and rules in Carnation

The drainage permit excludes single-family residential development, yet best management practices apply even when no permit is required. We check the source, the outlet, and whether the right-of-way is involved before any digging begins, and we confirm with the City Engineer where a discharge may go. If the trench or outlet extends into the road right-of-way, Public Works needs to issue a right-of-way permit as well.

Rules change and vary by parcel, so we confirm the current requirements with the city before we start.

How we approach it

Trace the entry points for water in the yard and the exit points off the lot
Set the drain upslope of the wet ground rather than at its lowest point
Carry downspouts in solid pipe so they stay apart from the perforated line
Flag any discharge that might run onto the street or a neighbor’s frontage

For the full process, see our Drainage Systems & French Drains page.

Questions from Carnation homeowners

Which outlets suit a Carnation French drain?

Onto your own lot, across ground that can handle the flow, or into a point the city accepts. The city has no network for runoff from outside its tributary areas, so we take the outlet to the City Engineer before any digging.

Would a French drain on a Carnation lot draw a permit?

Single-family work is excluded from the drainage permit, but a right-of-way permit is still needed if the trench or outlet extends into the road right-of-way. We confirm both points for your address before the trench opens.

Will a drain fix a soggy Carnation yard below a slope?

It can, once we confirm where the water comes from. Water arriving down a slope from above may call for an interception line above the yard. The slope itself may need its own review, so the grade and soil get checked before any result is promised.