St. Clair County, Missouri
The dominant drainage class is Well drained and the dominant hydrologic group is C (slow infiltration, moderate runoff). 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, Missouri.
| Soil Map Unit | Acres | Drainage | Hydro Group | Dwellings | Septic |
|---|---|---|---|---|---|
| Barden silt loam, 1 to 5 percent slopes | 54K | Moderately well drained | D | Very limited | Very limited |
| Hector fine sandy loam, 5 to 25 percent slopes, stony | 44K | Well drained | D | Very limited | Very limited |
| Barco fine sandy loam, 2 to 5 percent slopes | 32K | Well drained | C | Somewhat limited | Very limited |
| Gasconade-Rock outcrop complex, 3 to 35 percent slopes | 27K | Somewhat excessively drained | D | Very limited | Very limited |
| Goss gravelly silt loam, 8 to 15 percent slopes | 25K | Well drained | C | Somewhat limited | Very limited |
| Goss gravelly silt loam, 3 to 8 percent slopes | 24K | Well drained | C | Not limited | Very limited |
| Bolivar fine sandy loam, 2 to 5 percent slopes | 19K | Well drained | C | Somewhat limited | Very limited |
| Deepwater silt loam, 2 to 5 percent slopes | 17K | Moderately well drained | C | Somewhat limited | Very limited |
| Water | 16K | Subaqueous | Not rated | Not rated | |
| Collinsville fine sandy loam, 2 to 20 percent slopes | 15K | Somewhat excessively drained | D | Very limited | Very limited |
| Goss very gravelly silt loam, 15 to 35 percent slopes, very stony | 14K | Well drained | C | Very limited | Very limited |
| Bolivar fine sandy loam, 5 to 9 percent slopes | 12K | Well drained | C | Very limited | Very limited |
| Barco fine sandy loam, 5 to 9 percent slopes | 12K | Well drained | C | Somewhat limited | Very limited |
| Hartwell silt loam, 0 to 1 percent slopes | 10K | Somewhat poorly drained | C/D | Very limited | Very limited |
| Eldorado gravelly silt loam, 3 to 8 percent slopes | 10K | Well drained | B | Not limited | Very limited |
| Kenoma silt loam, 1 to 3 percent slopes | 10K | Moderately well drained | D | Very limited | Very limited |
| Verdigris silt loam, 0 to 1 percent slopes, occasionally flooded | 10K | Well drained | B | Very limited | Very limited |
| Useful silt loam, 3 to 8 percent slopes | 8K | Moderately well drained | C | Somewhat limited | Very limited |
| Liberal silt loam, 3 to 8 percent slopes | 6K | Moderately well drained | D | Very limited | Very limited |
| Quarles silt loam, 0 to 2 percent slopes, rarely flooded | 6K | Poorly drained | C/D | Very limited | Very limited |
What This Means
Building & Foundations
About 56% 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 95% 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.