Darrington sits up against the Cascades, with Whitehorse Mountain on the skyline and a harder rain than the towns down on the flats. Soils run rocky, lots break off into steep cuts, and water does not sheet across a lawn so much as it cuts a track and takes the soil with it. On a hillside the drain belongs above the lawn and above the wall, where the water is still concentrated. A drain at the bottom is a mop.
Snohomish County · ZIP 98241 · 2020 population 1,358
Intercept the water at the top of the slope
We cut a line across the slope, deep enough to catch the seep, and we outlet it to the side, not down the middle of the yard. The pipe has to be protected from the rock and the fill that move every winter. Cleanouts go in where a mountain silt load will eventually arrive.
A French drain is not a retaining wall. If the bank is moving, the wall comes first or with it. Pipe alone in a slumping cut just becomes a crushed pipe.
The ground in Darrington
This is a small town with mountain weather. A wall that would be decorative in Mill Creek is structural here: it is holding a bank that wants to move every winter. We see shallow, rocky ground, overhanging fir and hemlock, and driveways that wash out where the grade dumps onto the road.
Planting lists shrink to what can handle cold, wet, and poor soil. Huckleberry and mountain hemlock already grow on the edges of these properties. A lawn is possible on the flatter bench of a lot, but it needs seed and soil that can take a short season, not a turf schedule copied from Everett. Cleanup is often about limbs over the roof and ditches that have filled with gravel from the bank above.
How we do the work
A French drain is a perforated pipe in washed rock, wrapped so the fines do not fill it, sloped to a place the water can actually leave. We do not end a drain in a dry well of hope, and we do not outlet it at the neighbor’s shed.
The trench is deep enough to catch the water you are chasing, which is often the downspout and the wet line along the foundation, not a decorative strip in the middle of the lawn. Surface grading still matters. A drain cannot fix a patio that pitches at the house.
What we look at first
- Where the water shows up, and where it can daylight
- Downspouts that are dumping at the footing
- Utilities before we trench
- Whether the wet spot is a seep that will need more than one line
Downspouts
Solid pipe until it is away from the house, then into the drain if the drain can take the roof. We do not dump a whole roof into a two-inch pop-up in the middle of the lawn and call it drainage.
What the trench looks like
Fabric, washed rock, pipe with the holes oriented the way the detail calls for, then rock, then fabric closed, then soil. The lawn or the bark goes back on top. A trench of pit-run gravel with a pipe tossed in will silt up, and we do not build those.
Maintenance
Silt arrives. Cleanouts and a flush every few years keep the pipe a pipe. Catch basins, if we used one, need the leaves emptied. A drain with no access becomes a dig when it clogs, so we put the access in.
More from this crew
- French drain installation across Snohomish County
- Retaining walls in Darrington
- Gravel installation in Darrington
- Landscaping in Darrington
- Patio installation in Darrington
- French drain installation in Granite Falls
- French drain installation in Arlington
Sources for the climate and the water
- USDA plant hardiness map for choosing plants that can take a Snohomish County winter.
- EPA WaterSense on watering less once a lawn or a new planting is established.
- EPA Soak Up the Rain on keeping roof and yard water from becoming someone else’s problem.
