Excavation contractors in Multnomah County, OR

Oregon stacks marine mountains, a glacial-flood valley, and lava plains. The Willamette Valley (Portland, Eugene, Salem) is the workhorse: deep alluvial and Missoula-flood silts and clays, wet winters with hydric soils across a third of the valley, seasonal high water, and the valley's shrink-swell clays localized in the southern reaches (the Eugene and Corvallis clays). Digging is easy; winter saturation and trench stability drive the schedule. The Coast Range (Newport, Coos Bay, Astoria) is marine sandstone and siltstone: steep, dissected, slide-prone hillsides (the Coast Range is one of the nation's landslide hotspots), shallow bedrock on ridge crests, and heavy rain loading every winter. The High Lava Plains and the Columbia Plateau (Bend, Madras, The Dalles) are basalt and volcaniclastics: rock excavation ordinary, pumice soils in places, and lahar and fault zones mapped around the Cascades volcanoes. The Klamath Mountains (Medford, Grants Pass) add serpentinite, gold-country gravels, and the state's most complicated rock assemblages. Frost is shallow everywhere (10-20 inches).