St. Clair County, Illinois
The dominant drainage class is Somewhat poorly drained and the dominant hydrologic group is C/D (varies with drainage). 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 St. Clair County, Illinois.
| Soil Map Unit | Acres | Drainage | Hydro Group | Dwellings | Septic |
|---|---|---|---|---|---|
| Wakeland silt loam, 0 to 2 percent slopes, frequently flooded | 32K | Somewhat poorly drained | B/D | Very limited | Very limited |
| Herrick silt loam, 0 to 2 percent slopes | 15K | Somewhat poorly drained | C/D | Very limited | Very limited |
| Cowden-Piasa silt loams, 0 to 2 percent slopes | 13K | Poorly drained | D | Very limited | Very limited |
| Bunkum-Coulterville silty clay loams, 5 to 10 percent slopes, severely eroded | 12K | Somewhat poorly drained | C/D | Very limited | Very limited |
| Marine silt loam, 0 to 2 percent slopes | 12K | Somewhat poorly drained | C/D | Very limited | Very limited |
| Homen silt loam, 2 to 5 percent slopes | 12K | Moderately well drained | C | Somewhat limited | Very limited |
| Winfield silt loam, 2 to 5 percent slopes | 11K | Moderately well drained | C | Somewhat limited | Very limited |
| Marine silt loam, 2 to 5 percent slopes | 10K | Somewhat poorly drained | C/D | Very limited | Very limited |
| Urban land | 10K | Not rated | Not rated | ||
| Water | 10K | Not rated | Not rated | ||
| Coulterville-Grantfork silty clay loams, 5 to 10 percent slopes, severely eroded | 9K | Somewhat poorly drained | C/D | Very limited | Very limited |
| Menfro silt loam, 2 to 5 percent slopes | 9K | Well drained | C | Somewhat limited | Somewhat limited |
| Menfro silt loam, 5 to 10 percent slopes, eroded | 8K | Well drained | B | Somewhat limited | Somewhat limited |
| Edwardsville silt loam, 0 to 2 percent slopes | 8K | Somewhat poorly drained | B/D | Very limited | Very limited |
| Coulterville-Darmstadt silt loams, 2 to 5 percent slopes, eroded | 8K | Somewhat poorly drained | D | Very limited | Very limited |
| Petrolia silty clay loam, 0 to 2 percent slopes, frequently flooded, long duration | 7K | Poorly drained | C/D | Very limited | Very limited |
| Bunkum-Atlas silty clay loams, 10 to 18 percent slopes, severely eroded | 7K | Somewhat poorly drained | C/D | Very limited | Very limited |
| Oconee-Darmstadt-Coulterville silt loams, 0 to 2 percent slopes | 7K | Somewhat poorly drained | C/D | Very limited | Very limited |
| Ruma-Ursa silty clay loams, 18 to 35 percent slopes, severely eroded | 6K | Well drained | B | Very limited | Very limited |
| Shaffton-Fluvents-Urban land complex, 0 to 2 percent slopes, occasionally flooded | 6K | Somewhat poorly drained | Very limited | Very limited |
What This Means
Building & Foundations
About 71% 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 82% 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.