Soil survey area

Washington County, Pennsylvania

Survey Area PA125• Pennsylvania

The short version

The most common soil here is Dormont, on about 33% of the land: a silt loam, smooth, like flour. Culleoka and Guernsey come next.

About 27% of the land drains well, and 6% stays wet for long stretches; groundwater comes within two feet of the surface under 16% of it.

USDA rates 98% of the land very limited for a standard septic drain field, and 80% very limited for homes with basements. That means extra cost or special design, not that it can't be done.

Worth knowing: 6% of the land floods occasionally or more, and bedrock lies within 40 inches under 71% of it.

Soils change over short distances, so look up an address below for the soil at that exact spot and the reasons behind each rating.

The ground underfoot

The soils you're most likely standing on

The biggest named soils in Washington County, Pennsylvania, each drawn five feet deep from its official USDA description, in its recorded colors.

Dormont

33% of the area

Silt loam topsoil · moderately well drained

Smooth, like flour. Fertile and holds water well.

Alfisols

Culleoka

29% of the area

Silt loam topsoil · well drained

Smooth, like flour. Fertile and holds water well.

Alfisols

Guernsey

9% of the area

Silt loam topsoil · moderately well drained

Smooth, like flour. Fertile and holds water well.

Alfisols

Lowell

5% of the area

Silt loam topsoil · well drained

Smooth, like flour. Fertile and holds water well.

Alfisols

Weikert

4% of the area

Channery silt loam topsoil · somewhat excessively drained

Smooth, like flour. Fertile and holds water well.

Inceptisols

Dots mark gravel; white flecks mark lime. Shares are by acres across the survey area, and each mapped patch usually mixes several of these soils.

The biggest mapped areas

The dominant drainage class is Moderately well drained and the dominant hydrologic group is D (very slow infiltration, high runoff). The most common soil order is Alfisols — moderately leached forest soils with a clay-enriched subsoil. 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 Washington County, Pennsylvania. 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
Dormont-Culleoka complex, 25 to 50 percent slopes	112K	Moderately well drained	D	Very limited	Very limited
Dormont-Culleoka complex, 15 to 25 percent slopes	89K	Moderately well drained	D	Very limited	Very limited
Dormont silt loam, 8 to 15 percent slopes	71K	Moderately well drained	D	Somewhat limited	Very limited
Culleoka channery silt loam, 15 to 25 percent slopes	37K	Well drained	B	Very limited	Very limited
Guernsey silt loam, 8 to 15 percent slopes	22K	Moderately well drained	C/D	Very limited	Very limited
Weikert-Culleoka complex, 15 to 25 percent slopes	21K	Somewhat excessively drained	D	Very limited	Very limited
Culleoka channery silt loam, 8 to 15 percent slopes	21K	Well drained	B	Very limited	Very limited
Dormont silt loam, 15 to 25 percent slopes	19K	Moderately well drained	D	Very limited	Very limited
Newark silt loam, 0 to 3 percent slopes, frequently flooded	17K	Somewhat poorly drained	B/D	Very limited	Very limited
Fluvaquents, loamy	13K	Poorly drained	B/D	Very limited	Very limited
Guernsey silt loam, 15 to 25 percent slopes	13K	Moderately well drained	C/D	Very limited	Very limited
Dormont silt loam, 3 to 8 percent slopes	12K	Moderately well drained	D	Somewhat limited	Very limited
Culleoka channery silt loam, 3 to 8 percent slopes	12K	Well drained	B	Very limited	Very limited
Weikert-Culleoka complex, 3 to 8 percent slopes	11K	Somewhat excessively drained	D	Very limited	Very limited
Udorthents, strip mine, steep	9K	Well drained	C	Very limited	Very limited
Guernsey silt loam, 3 to 8 percent slopes	9K	Moderately well drained	C/D	Very limited	Very limited
Glenford silt loam, 3 to 8 percent slopes	9K	Moderately well drained	C/D	Very limited	Very limited
Weikert-Culleoka complex, 8 to 15 percent slopes	9K	Somewhat excessively drained	D	Very limited	Very limited
Urban land	6K			Not rated	Not rated
Udorthents, strip mine, moderately steep	5K	Well drained	C	Somewhat 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.

Alfisols

Moderately weathered forest soils with clay-enriched subsoil. Productive for agriculture, generally good for building and septic.

Entisols

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

Inceptisols

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

Ultisols

Strongly weathered clay soils of the Southeast. Acidic and naturally low in nutrients. Clay subsoil can slow drainage.

What This Means

Building & Foundations

About 80% of soils are rated "very limited" for dwellings with basements. Specific challenges include shallow bedrock, steep slopes, poor drainage in some areas, flood-prone areas. A geotechnical assessment is recommended before building.

Septic Systems

About 98% 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.

Look Up a Specific Address