Landscape design and build in Tigard.

Silt over clay, on a slope

The flats near Fanno Creek behave much like Beaverton — silt loam over a slow subsoil. Bull Mountain is the interesting part: a layer of permeable soil sitting on clay and basalt, tilted.

Water soaks in at the top of the hill, cannot get down through the clay, and travels laterally along the interface until the ground surface cuts across it. Where those two meet, you get a seep — a permanently soft patch mid-slope that appears in November, has no obvious source, and is nowhere near a downspout.

You cannot fix a seep from the surface

The common mistake is a french drain laid across the wet patch. The water is arriving underground from uphill, so a surface drain intercepts almost none of it. What works is an interceptor drain cut in above the seep line, deep enough to reach the clay layer, with a real outfall. It is not a cheap detail and it is the difference between a garden and a bog.

Deer

Real on Bull Mountain, particularly the upper streets backing onto undeveloped slope. Manageable with the plant list rather than with fencing.

The lots

Very mixed. Newer Bull Mountain lots are steep and tightly packed with impressive views and difficult access. Summerfield and Metzger are flatter, older and easier to build in.

Fanno Creek is a regulated corridor

Clean Water Services vegetated corridors and Tigard's own floodplain provisions both apply along Fanno Creek and its tributaries. If you back onto it, we establish the line before we design, not after.