French Drains & Drainage Systems in Covington, WA

Drainage & French drains in Covington: what to know

The soil survey’s Alderwood description puts a dense layer about 20 to 40 inches down, with a perched water table above it at times from December through April. A yard on that soil can stay spongy for months and dry out by August. A curtain drain uphill of the wet ground intercepts water moving along that layer. On Everett outwash soil, water usually soaks in, and an infiltration trench may do the work instead.

Near Big Soos Creek, Jenkins Creek, or a mapped wetland, the buffers set the layout. Standard stream buffers run 100 to 125 feet and wetland buffers 40 to 225 feet, so an outlet on that side of a lot may not be available.

Permits and rules in Covington

Covington follows Ecology’s stormwater manual. Drainage review applies to a project that needs a city permit and also adds or replaces 2,000 square feet of impervious surface, disturbs 7,000 square feet, builds or alters a pipe or ditch 12 inches or larger, or lies next to a stream, wetland, floodplain, or other critical area. Excavation under three feet deep and 50 cubic yards is exempt from the grading permit. We look up which of these your drain and outlet trigger 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

Dig a test hole to find the dense layer and any standing water
Mark stream, wetland, and steep slope buffers before choosing an outlet
Send downspouts through solid tightline, separate from the perforated drain
Keep discharge spread out on your own lot, clear of neighbors

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

Questions from Covington homeowners

Where can a French drain discharge on a Covington lot?

On your own lot, spread out: dispersion, an infiltration trench, or the lot’s storm stub where one exists. The city’s wall code shows the pattern, barring discharge onto a downhill neighbor or steep ground, and we apply it to yard drains. Sanitary sewer lines are off limits.

Do I need a permit to install a French drain in Covington?

A short residential trench often falls under the grading exemption for excavation less than three feet deep and 50 cubic yards or less. Work near a stream, wetland, or steep slope gets separate review, and a tie-in to the city system needs approval. We confirm before digging.

My Covington yard stays wet near the creek. Will a drain fix it?

Maybe not. Near Soos or Jenkins creek the water table may be the cause, not roof runoff, and the city’s flood damage chapter requires a development permit in a mapped flood hazard area. We check the map and buffer before promising a drain.