King County Area, Washington

Survey Area WA633• Washington

The dominant drainage class is Moderately well drained and the dominant hydrologic group is B (moderate infiltration). 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 King County Area, 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
Alderwood gravelly sandy loam, 8 to 15 percent slopes	126K	Moderately well drained	B	Very limited	Very limited
Alderwood gravelly sandy loam, 0 to 8 percent slopes	29K	Moderately well drained	B	Very limited	Very limited
Everett very gravelly sandy loam, 8 to 15 percent slopes	28K	Somewhat excessively drained	A	Somewhat limited	Very limited
Alderwood and Kitsap soils, very steep	27K	Moderately well drained	B	Very limited	Very limited
Alderwood gravelly sandy loam, 15 to 30 percent slopes	19K	Moderately well drained	B	Very limited	Very limited
Arents, Alderwood material, 6 to 15 percent slopes	14K	Moderately well drained	B/D	Very limited	Very limited
Buckley gravelly silt loam, 0 to 3 percent slopes	14K	Poorly drained	C/D	Very limited	Very limited
Everett very gravelly sandy loam, 0 to 8 percent slopes	13K	Somewhat excessively drained	A	Not limited	Very limited
Urban land	12K			Not rated	Not rated
Water	11K			Not rated	Not rated
Everett-Alderwood gravelly sandy loams, 6 to 15 percent slopes	10K	Somewhat excessively drained	A	Somewhat limited	Very limited
Kitsap silt loam, 2 to 8 percent slopes	9K	Moderately well drained	C	Very limited	Very limited
Seattle muck	8K	Very poorly drained	B/D	Very limited	Very limited
Beausite gravelly sandy loam, 15 to 30 percent slopes	5K	Well drained	C	Very limited	Very limited
Beausite gravelly sandy loam, 6 to 15 percent slopes	4K	Well drained	C	Very limited	Very limited
Everett very gravelly sandy loam, 15 to 30 percent slopes	4K	Somewhat excessively drained	A	Very limited	Very limited
Indianola loamy sand, 5 to 15 percent slopes	4K	Somewhat excessively drained	A	Not limited	Very limited
Norma sandy loam	4K	Poorly drained	A/D	Very limited	Very limited
Puyallup fine sandy loam	4K	Well drained	A	Very limited	Very limited
Kitsap silt loam, 15 to 30 percent slopes	4K	Moderately well drained	C	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

About 77% of soils are rated "very limited" for dwellings with basements. Specific challenges include steep slopes, poor drainage in some areas, flood-prone areas. A geotechnical assessment is recommended before building.

Septic Systems

About 93% of soils are rated "very limited" for septic absorption fields. Despite good drainage overall, limitations may stem from shallow bedrock, steep slopes, or seasonal conditions. Engineered or alternative systems are frequently required. Always get a professional perc test before purchasing land that needs septic.

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.