Hillside and Retaining Wall Assessment in the West Hills, Portland
West Hills retaining walls fail because of water rather than because of soil weight, and the distinction determines what the repair is. A wall designed for the pressure of drained soil sees a substantially higher load once the ground behind it is saturated, because water adds both weight and its own pressure while removing much of the soil's internal friction.
In a climate with a long wet season that condition is not exceptional, it is annual. So a wall that appears to be failing under load is usually failing under load it should never have been carrying, and the useful finding is generally about the drainage behind it — whether there is any, whether it was ever connected to anything, and whether it is blocked.
The wall is also a symptom. Movement in a retaining structure on a West Hills lot can be the first visible sign of broader slope movement, and distinguishing "this wall is inadequate" from "this slope is moving" is the most consequential judgement on the site. The second is a geotechnical question, and part of the assessment is saying plainly when the answer needs one.
What We Look At Here
- Wall movement measured: lean, bulge and any rotation at the base
- Drainage behind the wall — whether it exists, is connected and is functioning
- Evidence of saturation: seepage, staining, vegetation patterns above the wall
- Surcharge above the wall from driveways, structures or continuing slope
- Whether ground movement extends beyond the wall, indicating slope rather than wall failure
- Mapped landslide hazard status and whether a geotechnical investigation is warranted
More on the service itself: Hillside & Retaining Wall Assessment. More on the area: West Hills.
Questions
Frequently Asked Questions
My West Hills retaining wall is leaning. Is the hillside moving?
Not necessarily, and separating those two is the point of the assessment. A wall can be inadequate for saturated conditions on a perfectly stable slope. Evidence of movement in the ground beyond the wall is what distinguishes them.