French Drains & Drainage Systems in White Center, WA

Drainage & French drains in White Center: what to know

A project under drainage review on a lot under 22,000 square feet falls in the county’s Small Lot set, which asks first whether full dispersion works for the roof and driveway. Most of the area is zoned R-6, six homes per acre, so a typical lot is well under that size. When flow is too large to spread out, the county can require a pipe across downstream lots, with recorded easements.

The White Center Ponds collect runoff from 72 acres the county calls highly urbanized and mostly impervious, and treated water moves on to Salmon Creek and Puget Sound. The county’s guidance calls hardpan and silty or clayey loams unsuitable for limited infiltration, so a test hole decides between a soak-away trench and a tightline.

Permits and rules in White Center

County drainage review covers projects on unincorporated parcels, and a pipe or ditch 12 inches or larger, or a site next to a flood hazard area, takes a project out of the no-review tier. Where a parcel lies in a landslide hazard drainage area, runoff crossing steep erodible ground generally has to go through a tightline instead. We check which of these your parcel and outlet trigger, using county records, before we quote.

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

How we approach it

Walk the lot after a storm to see where water enters and leaves
Dig a test hole before choosing between a soak-away trench and a tightline
Check the county’s landslide and steep slope layers before aiming a pipe downhill
Spread discharge on your own lot, because crossing downstream lots needs recorded easements

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

Questions from White Center homeowners

Can I run my downspouts and a French drain to the street in White Center?

Only if the street is where that water naturally goes and the county accepts the connection. That touches county right-of-way, which can mean a right-of-way use permit, and a pipe or ditch of 12 inches or larger is a drainage review trigger. Seattle and Burien streets follow their own rules.

Why does the low corner of my White Center yard stay wet, and what can a drain do?

It depends on the source. Roof water dumped in one spot, a slope sending runoff across the lot, or soil that will not drain can each hold water. A curtain drain helps with the second, a tightline with the first, and a test hole shows which you have.

Does a French drain near a steep slope in White Center get extra review?

It can. Where a project drains toward a landslide, steep slope, or erosion hazard area, the county asks for proof the drainage will not harm properties downhill, and a tightline can be required over steep erodible ground. A geotechnical report may be needed within 65 feet of a mapped slope.