Quick Verdict
Yard drainage excavation is the work of regrading and trenching a property so surface and subsurface water moves away from the house instead of pooling in the yard. A yard catch basin is the collection point: a boxed inlet with a grate that catches runoff and feeds it into a buried pipe that daylights somewhere safe. In Oregon's long wet season, a soggy backyard is almost always a grading and drainage problem, not a soil problem you can fix with more topsoil. The right combination of catch basins, French drains, and positive slope solves it for good.
Why Oregon Yards Flood
The Willamette Valley gets months of steady rain on top of clay-heavy soil that drains slowly. Water that hits a flat or low yard has nowhere to go, so it sits. Common culprits:
- Ground that slopes toward the house instead of away from it
- Downspouts dumping roof water right at the foundation
- A low spot in the middle of the yard with no outlet
- Compacted clay that will not absorb water
- A neighbor's lot draining onto yours
The fix is almost never "add dirt." It is moving water on purpose, with slope and pipe, to a place it can safely leave.
The Tools of Yard Drainage
A good backyard drainage dig usually combines a few methods, matched to where the water is coming from.
| Method | What It Solves | How It Works |
|---|---|---|
| Catch basin | Surface ponding, low spots | Grated box collects runoff into a pipe |
| French drain | Saturated soil, hillside seep | Perforated pipe in gravel intercepts subsurface water |
| Surface grading | Slope toward house | Reshapes ground to shed water away |
| Downspout tie-in | Roof water at foundation | Pipes gutters underground to daylight |
| Dry well | No downhill outlet available | Buried gravel chamber lets water infiltrate |
How the Excavation Works
A yard drainage project follows a clear sequence:
- Survey the grade and find the low points and the best outlet.
- Call 811 and mark all utilities before digging.
- Excavate trenches to consistent slope, typically 1 to 2 percent fall.
- Set catch basins at collection points and bed pipe in gravel.
- Connect downspouts and any subsurface French drains into the system.
- Route everything to a daylight outlet, dry well, or storm system.
- Backfill, compact, and restore turf or landscaping.
The slope is the make-or-break detail. A pipe that runs flat or backpitches silts up and stops working. If your drainage ties into a larger storm drain and catch-basin installation, the outlet and pipe sizing get coordinated with that system.
What Yard Drainage Excavation Costs
Cost tracks the length of pipe, the number of basins, and how much regrading the yard needs. A single catch basin with a short run is a small job; a full-yard system with French drains and multiple inlets is a multi-day project.
Industry Baseline Range: a simple catch basin with a short daylight run typically runs about $1,200 to $4,000+, while a full yard drainage system with French drains, multiple basins, and regrading commonly lands around $4,500 to $15,000+.
These are industry baseline ranges for planning only -- actual pricing depends on site conditions, soil, access, depth, haul-off, and current market conditions. Get a site-specific quote.
| Component | Baseline Range |
|---|---|
| Trenching, per linear foot | $8 - $40+ per linear foot |
| French drain, per linear foot | $15 - $120+ per linear foot |
| Catch basin, each installed | $300 - $1,200+ |
| Grading / leveling, per sq ft | $0.75 - $4.00+ per sq ft |
| Minimum job callout | $500 - $1,500+ |
Current Market Reality
Real costs run 2 to 3 times baseline when the yard has no gravity outlet and needs a pumped system or dry well, when clay soil requires extra gravel and fabric, or when the trench crosses hardscape like a driveway or patio that has to be cut and restored. Long runs to reach a legal discharge point add up fast.
Getting It Right in Oregon Soils
Clay is the reason drainage matters here. It holds water at the surface and against the foundation, so French drains need a full gravel envelope and filter fabric to keep from clogging. Discharge cannot legally tie into the sanitary sewer, and many jurisdictions regulate where stormwater can go, so the outlet is planned around local rules. If foundation seepage is part of the problem, pair the yard work with footing and foundation drain excavation so you solve surface and subsurface water in one dig. The wider site-drainage picture is in our Oregon excavation contractor guide.
Timing, Permits, and Where Oregon Stormwater Can Go
Yard drainage is dry-season work. The stretch from roughly May through October is when you want trenches open: winter digging turns the yard to mud, silts the pipe before it is bedded, and leaves ruts that take a season to recover. Trenching to a clean 1 to 2 percent fall is also far easier in firm summer ground than in saturated clay that slumps back into the cut. If a wet backyard has already made itself obvious over the winter, plan and quote the fix early so the crew can dig once the ground dries.
Where the water is allowed to go is set by local rules, not just by the low point of your lot:
- It can daylight downhill on your own property, well away from the foundation and off the neighbor's line.
- It can feed a dry well that infiltrates on site -- often the answer on flat lots with no gravity outlet.
- It can tie into an approved public storm system only where the jurisdiction permits it.
- It can never connect to the sanitary sewer, which is against code statewide.
Many Oregon cities, including Portland, Eugene, and Bend, regulate stormwater and may require on-site infiltration rather than piping runoff to the street, so the outlet is confirmed before the trenching plan is final. Call 811 before any dig. Most backyard projects fall under the one-acre threshold that triggers a DEQ 1200-C erosion permit, but a large rural lot or a drainage job tied to new construction can cross it. Cojo is CCB licensed and insured, so the plan is built around the rules that actually apply to your address.
The Bottom Line
A wet yard is a solvable problem, and the solution is grade and pipe, not guesswork. Catch basins collect it, French drains intercept it, slope carries it, and a planned outlet gets rid of it. Do it once, correctly, and the backyard drains for decades. Cojo is CCB licensed and insured and handles yard drainage, catch basins, and grading statewide. See our excavation services or request a free estimate.