Soil survey area

Franklin County, Illinois

Survey Area IL055• Illinois

The short version

The most common soil here is Bluford, on about 18% of the land: a silt loam, smooth, like flour. Ava and Belknap come next.

About 6% of the land drains well, and 61% stays wet for long stretches; groundwater comes within two feet of the surface under 61% of it.

USDA rates 91% of the land very limited for a standard septic drain field, and 82% very limited for homes with basements. That means extra cost or special design, not that it can't be done.

Worth knowing: 20% of the land floods occasionally or more, and bedrock lies within 40 inches under 2% 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 Franklin County, Illinois, each drawn five feet deep from its official USDA description, in its recorded colors.

Bluford

18% of the area

Silt loam topsoil · somewhat poorly drained

Smooth, like flour. Fertile and holds water well.

Alfisols

Ava

12% of the area

Silt loam topsoil · moderately well drained

Smooth, like flour. Fertile and holds water well.

Alfisols

Belknap

9% of the area

Silt loam topsoil · somewhat poorly drained

Smooth, like flour. Fertile and holds water well.

Inceptisols

Hoyleton

7% of the area

Silt loam topsoil · somewhat poorly drained

Smooth, like flour. Fertile and holds water well.

Alfisols

Bonnie

7% of the area

Silt loam topsoil · poorly drained

Smooth, like flour. Fertile and holds water well.

Entisols

Wynoose

6% of the area

Silt loam topsoil · poorly drained

Smooth, like flour. Fertile and holds water well.

Alfisols

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 Somewhat poorly drained and the dominant hydrologic group is C/D (varies with drainage). 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 Franklin County, Illinois. 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
Belknap silt loam, 0 to 2 percent slopes, frequently flooded	26K	Somewhat poorly drained	B/D	Very limited	Very limited
Bluford silt loam, 0 to 2 percent slopes	26K	Somewhat poorly drained	C/D	Very limited	Very limited
Ava silt loam, 2 to 5 percent slopes	20K	Moderately well drained	C	Very limited	Very limited
Bluford silt loam, 2 to 5 percent slopes, eroded	16K	Somewhat poorly drained	C/D	Very limited	Very limited
Water	15K			Not rated	Not rated
Bonnie silt loam, 0 to 2 percent slopes, frequently flooded	14K	Poorly drained	C/D	Very limited	Very limited
Hoyleton silt loam, 0 to 2 percent slopes	11K	Somewhat poorly drained	C/D	Very limited	Very limited
Blair silty clay loam, 5 to 10 percent slopes, severely eroded	11K	Somewhat poorly drained	C/D	Very limited	Very limited
Plumfield silty clay loam, 5 to 10 percent slopes	10K	Moderately well drained	D	Somewhat limited	Very limited
Ava silt loam, 5 to 10 percent slopes, eroded	9K	Moderately well drained	C	Very limited	Very limited
Wynoose silt loam, 0 to 2 percent slopes	8K	Poorly drained	C/D	Very limited	Very limited
Ava silt loam, 2 to 5 percent slopes, eroded	8K	Moderately well drained	C	Very limited	Very limited
Bluford silt loam, bench, 0 to 2 percent slopes	7K	Somewhat poorly drained	C/D	Very limited	Very limited
Wynoose silt loam, bench, 0 to 2 percent slopes	7K	Poorly drained	C/D	Very limited	Very limited
Cisne silt loam, 0 to 2 percent slopes	6K	Poorly drained	C/D	Very limited	Very limited
Rend silt loam, 2 to 5 percent slopes, eroded	5K	Moderately well drained	C	Very limited	Very limited
Cape silty clay loam, 0 to 2 percent slopes, frequently flooded	5K	Poorly drained	D	Very limited	Very limited
Hoyleton silt loam, 2 to 5 percent slopes, eroded	5K	Somewhat poorly drained	C/D	Very limited	Very limited
Hickory clay loam, 10 to 18 percent slopes, severely eroded	5K	Well drained	B	Somewhat limited	Somewhat limited
Grantsburg silt loam, 2 to 5 percent slopes	4K	Moderately 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.

What This Means

Building & Foundations

About 82% of soils are rated "very limited" for dwellings with basements. Specific challenges include poor drainage in some areas, flood-prone areas. A geotechnical assessment is recommended before building.

Septic Systems

About 91% of soils are rated "very limited" for septic absorption fields. Poorly drained soils can't absorb septic effluent effectively. Engineered or alternative systems are frequently required. Always get a professional perc test before purchasing land that needs septic.

Gardening & Agriculture

Many soils hold water for extended periods. Raised beds are highly recommended to improve drainage for vegetables. Well-adapted native plants and water-loving species will do best in natural conditions.

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