French Drain Installation in Beaverton, Oregon: Cost & Process

French Drains in Beaverton's Valley Clay

Beaverton sits in the western Portland metro where the Tualatin Valley floor meets the west hills, and that mix of terrain creates a particular drainage challenge. Down on the valley floor the soil is heavy clay that holds water and drains slowly. Up against the slopes that run toward the Tualatin Mountains, runoff comes downhill and collects on the lower lots. Both situations share the same villain — months of steady Pacific Northwest rain on ground that does not let water through easily.

A French drain is one of the most effective answers to both problems. It is a gravel-filled trench with a perforated pipe that collects subsurface water and carries it to a safe outlet, and it works equally well intercepting hillside runoff or draining waterlogged clay. This guide explains how French drains are installed in Beaverton, what affects the cost, and why Washington County's soil and terrain make them so valuable.

For the full drainage picture, start with our guide to property and site drainage in Oregon. For statewide pricing detail, see French drain cost in Oregon.

When a Beaverton Property Needs a French Drain

• A chronically soggy yard — Valley clay holds water at the surface, leaving lawns spongy for weeks.
• Runoff from a slope or uphill neighbor — On Beaverton's hillside lots, water flows downhill and collects against the house or in the yard below.
• A wet basement or crawlspace — Saturated clay against the foundation pushes moisture into below-grade spaces.
• Standing water that will not drain — On flatter valley lots, surface water has little slope to follow and simply sits.

How a French Drain Is Installed in Beaverton

1. Site Assessment and Outlet Planning

The job begins with where the water comes from and where it will go. On a Beaverton hillside lot the installer may design the drain as an interceptor uphill of the structure; on a flat valley lot the focus shifts to finding a viable outlet — a daylight point, a dry well, or a storm connection — and dealing with slow-draining clay.

2. Trench Excavation

The trench is dug to a steady depth with a consistent downhill slope, typically 1 percent or more. Beaverton's clay is dense and heavy and can smear the trench walls, while hillside lots may put the trench across a grade that requires careful benching. The crew maintains positive fall toward the outlet throughout.

3. Fabric, Gravel, and Pipe

Filter fabric lines the trench — essential in Beaverton, where fine clay and silt will clog an unprotected drain quickly. A bed of clean drain rock goes down, then the perforated pipe (holes down), then more rock, then the fabric folds over the top to seal out sediment.

4. Backfill and Restoration

The trench is backfilled, compacted, and restored to grade. A well-built drain disappears into the landscape within a season while quietly moving water for decades.

Our excavation services cover the trenching and grading these installations require.

What French Drain Installation Costs in Beaverton

French drains are priced per linear foot, with the total driven by length, depth, soil, and outlet. Industry baseline ranges commonly referenced include:

Factor	Industry Baseline Range
French drain (per linear foot)	$25–$60
Typical residential run (50–100 ft)	$1,500–$6,000+
Dry well outlet (each)	$1,500–$4,000

In Beaverton, cost drivers include the length of the run, the depth, the distance to a workable outlet, and the terrain — a hillside interceptor on a grade can involve more labor than a flat-lot drain. Heavy clay may also require a more robust outlet, since the surrounding soil will not absorb overflow. A shorter run to a nearby daylight point sits at the low end; a longer hillside or dry-well system runs higher. Only a site assessment gives an accurate number. See French drain cost in Oregon for the broader breakdown.

Why Beaverton's Terrain Makes a Local Eye Matter

Beaverton properties vary more than most — a flat valley lot and a hillside lot a mile apart need different drainage designs. On the slopes, the priority is intercepting runoff before it reaches the structure; on the valley floor, it is finding an outlet that clay will not provide on its own. A contractor who works Washington County reads the terrain, identifies where the water is actually coming from, and uses filter fabric correctly so the fine silt the clay sheds does not clog the system. That local read is what makes a Beaverton French drain work.

Get Your Beaverton French Drain Quote

Cojo Excavation & Asphalt installs French drains throughout Beaverton and Washington County, designed for both valley clay and hillside runoff. We assess your soil, slope, and where the water originates, plan the right outlet, and give you a real number based on your property.

Request a free drainage assessment and we will respond within 24 hours. Explore our full range of excavation services for Beaverton-area homes and businesses.