Soil series profile

Graymont soil series

Graymont is a moderately well drained soil with a silt loam surface, mapped on 50,223 acres in 8 counties in IL. Hydrologic group C.

#5910 by mapped area fine-silty Oxyaquic Argiudolls (Mollisols)

Drainage class: Moderately well drained
Hydrologic group: C
Typical topsoil pH: 6.4
Mapped area: 50k

Typical Graymont profile

Texture and pH by depth

Depth to scale. More strongly shaded layers hold more clay. Horizon names are the soil survey's (A = topsoil, B = subsoil, C = parent material).

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Typical Graymont horizons (representative values)
Depth	Texture	pH	Clay	Sand	Organic matter
0–12 in (Ap)	Silt loam	6.4	25%	5%	4%
12–33 in (Bt1)	Silty clay loam	6.4	31%	5%	1.1%
33–38 in (2Bt2)	Silty clay loam	7.2	31%	15%	0.3%
38–60 in (2C)	Silty clay loam	7.8	29%	15%	0.25%

Representative values from the most extensive Graymont map unit (Graymont silt loam, 2 to 5 percent slopes, survey area IL093). Other map units of this series vary within the series range.

Stock photo for illustration, not a sample of this soil series. Credit on the Sources & method page.

What this means

What Graymont soil means for gardens, lawns and septic systems

For gardens

Typical topsoil in Graymont soils is slightly acidic: pH 6.4, the range most vegetables, flowers and lawn grasses prefer.

Loamy topsoil (loam, silt loam and similar) covers 100% of mapped Graymont acres: generally the easiest soil to garden, holding moisture without staying waterlogged. The most common surface texture is silt loam (100% of mapped Graymont acres).

100% of mapped Graymont acres is moderately well to excessively drained, which suits most garden plants.

For lawns and yards

On 100% of mapped acres, rain soaks in slowly (hydrologic groups C and D, including dual groups that are D until drained). Expect runoff and puddles after heavy rain: core-aerate compacted lawns and keep ground sloping away from foundations.

For a septic system

For conventional septic absorption fields, NRCS rates 100% of the acres in mapped Graymont soils very limited, 0% somewhat limited and 0% not limited.

Where the soil is very limited (slow permeability, a high water table, flooding, shallow bedrock or steep slopes), alternative systems such as mound or sand-filter designs are common and cost more.

Only a licensed site evaluation or perc test at the actual lot decides whether a system is allowed and which design.

Generated from the mapped numbers above using fixed rules, not a site visit. See how these notes are written.

Where Graymont soil is found

Mapped acres

Graymont is mapped in Illinois.

Counties with the most mapped Graymont soil
County	Acres	Share of county land
Kendall County, IL	20,986	10.4%
Will County, IL	15,246	2.9%
Livingston County, IL	7,669	1.2%
DuPage County, IL	3,668	1.7%
Grundy County, IL	1,312	0.5%
LaSalle County, IL	908	0.1%
Cook County, IL	318	0.1%
Kane County, IL	116	0.0%

Septic absorption fields

NRCS rating, share of Graymont acres

Not limited 0%

Somewhat limited 0%

Very limited 100%

Septic tank absorption field rating across mapped Graymont acres. Scale 0 to 100% of mapped land.

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Septic tank absorption field rating across mapped Graymont acres.
Category	Share of acres
Not limited	0.0%
Somewhat limited	0.0%
Very limited	100.0%

Drainage, water table and flooding

Share of Graymont acres

Depth to seasonal high water table: About 2.6 feet (31 in) (median where reported).
Flooding: Not mapped as flooding on most acres.
Slope: Typically 3–3% (median 3%).
Topsoil organic matter: Median 4%.

Drainage class

Excessively drained 0%

Somewhat excessively drained 0%

Well drained 0%

Moderately well drained 100%

Somewhat poorly drained 0%

Poorly drained 0%

Very poorly drained 0%

Drainage class across mapped Graymont acres. Scale 0 to 100% of mapped land.

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Drainage class across mapped Graymont acres.
Category	Share of acres
Excessively drained	0.0%
Somewhat excessively drained	0.0%
Well drained	0.0%
Moderately well drained	100.0%
Somewhat poorly drained	0.0%
Poorly drained	0.0%
Very poorly drained	0.0%

Hydrologic soil group

A: fast infiltration (mostly sandy or gravelly) 0%

B: moderate infiltration 0%

C: slow infiltration 100%

D: very slow infiltration (clayey, shallow or wet) 0%

A/D: D as is, A if drained 0%

B/D: D as is, B if drained 0%

C/D: D as is, C if drained 0%

Hydrologic soil group across mapped Graymont acres. Scale 0 to 100% of mapped land.

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Hydrologic soil group across mapped Graymont acres.
Category	Share of acres
A: fast infiltration (mostly sandy or gravelly)	0.0%
B: moderate infiltration	0.0%
C: slow infiltration	100.0%
D: very slow infiltration (clayey, shallow or wet)	0.0%
A/D: D as is, A if drained	0.0%
B/D: D as is, B if drained	0.0%
C/D: D as is, C if drained	0.0%

Sources & data dates

Source: USDA NRCS Soil Survey Geographic Database (SSURGO), queried through Soil Data Access. Public domain.
Data date: SSURGO as published on November 3, 2026 (most recent survey area update October 26, 2026). NRCS refreshes SSURGO each October.
Scope: All map unit components named Graymont (component kind "Series") in SSURGO: 50,223 acres.
Method: Shares are by mapped acres of Graymont components. The profile comes from the single largest Graymont component. Full methodology.

Independent reference site. No government affiliation or endorsement.

Full narrative description: USDA Official Soil Series Description for Graymont.