City of Seattle, Washington

Survey Area WA775• Washington

The dominant drainage class is Moderately well drained and the dominant hydrologic group is A (high infiltration, low runoff). The most common soil order is Inceptisols — young soils with minimal horizon development but more than Entisols. This report summarizes the major soil map units across the survey area to help you understand what to expect when buying, building, or gardening in City of Seattle, Washington. Search your address to find the exact soil composition, drainage, and series details at your specific location.

Soil Map Unit	Acres	Drainage	Hydro Group	Dwellings	Septic
Urban land-Alderwood complex, 5 to 12 percent slopes	21K			Not rated	Not rated
Urban land-Alderwood complex, 0 to 5 percent slopes	20K			Not rated	Not rated
Urban land, 0 to 5 percent slopes	13K			Not rated	Not rated
Urban land-Alderwood complex, 12 to 35 percent slopes	11K			Not rated	Not rated
Urban land, 5 to 20 percent slopes	4K			Not rated	Not rated
Alderwood-Everett-Urban land complex, 12 to 35 percent slopes	3K	Moderately well drained	A	Very limited	Very limited
Alderwood-Everett-Urban land complex, 35 to 60 percent slopes	2K	Moderately well drained	A	Very limited	Very limited
Alderwood-Kitsap complex, 12 to 60 percent slopes	2K	Moderately well drained	A	Very limited	Very limited
Alderwood-Everett-Urban land complex, 0 to 12 percent slopes	1K	Moderately well drained	A	Very limited	Very limited
Alderwood-Everett complex, 0 to 12 percent slopes	1K	Moderately well drained	A	Very limited	Very limited
Alderwood-Everett complex, 12 to 35 percent slopes	1K	Moderately well drained	A	Very limited	Very limited
Anthraltic Xerorthents gravelly sandy loam, 0 to 12 percent slopes	840	Moderately well drained	A/D	Very limited	Very limited
Water, fresh	633			Not rated	Not rated
Alderwood-Everett complex, 35 to 60 percent slopes	382	Moderately well drained	A	Very limited	Very limited
Beaches-Endoaquents, tidal-Xerorthents association, 0 to 5 percent slopes	164			Very limited	Very limited
Mukilteo-Water complex, 0 to 2 percent slopes	126	Very poorly drained	A/D	Very limited	Very limited
Anthraltic Xerorthents gravelly sandy loam, 12 to 35 percent slopes	118	Moderately well drained	A/D	Very limited	Very limited
Urban land-Beausite complex, 12 to 35 percent slopes	101			Not rated	Not rated
Urban land-Beausite complex, 5 to 12 percent slopes	48			Not rated	Not rated
Beausite-Alderwood-Urban land complex, 12 to 35 percent slopes	35	Well drained	B	Very limited	Very limited

Soil Orders in This Area

The USDA classifies every soil into one of 12 soil orders. Here are the dominant orders found in this survey area.

Inceptisols

Young but developing soils found in mountains and river terraces. Variable properties — check drainage and bedrock depth.

Entisols

Young soils with little development — found on floodplains, dunes, and steep slopes. Properties vary widely by setting.

Histosols

Organic peat and muck soils formed in wetlands. Very poor for building (compressible) and septic. Often in regulated wetlands.

What This Means

Building & Foundations

Most soils are generally favorable for residential construction. Standard foundations are usually viable, though site-specific evaluation is always recommended.

Septic Systems

Most soils are reasonably suitable for conventional septic systems, though site-specific conditions always matter. Get a perc test to confirm.

Gardening & Agriculture

Well-drained soils on sloped terrain — good for most plants but watch for erosion. Terracing, contour planting, and mulching help retain moisture and topsoil. Drip irrigation is more effective than sprinklers on slopes.