Fairfax County, Virginia
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 Fairfax County, Virginia.
| Soil Map Unit | Acres | Drainage | Hydro Group | Dwellings | Septic |
|---|---|---|---|---|---|
| Urban land | 27K | Not rated | Not rated | ||
| Wheaton-Glenelg complex, 2 to 7 percent slopes | 19K | Well drained | C | Not limited | Very limited |
| Wheaton-Glenelg complex, 7 to 15 percent slopes | 18K | Well drained | C | Somewhat limited | Very limited |
| Codorus and Hatboro soils, 0 to 2 percent slopes, occasionally flooded | 12K | Somewhat poorly drained | B/D | Very limited | Very limited |
| Glenelg silt loam, 7 to 15 percent slopes | 12K | Well drained | B | Somewhat limited | Somewhat limited |
| Water | 8K | Not rated | Not rated | ||
| Glenelg silt loam, 15 to 25 percent slopes | 8K | Well drained | B | Very limited | Very limited |
| Urban land-Wheaton complex | 6K | Not rated | Not rated | ||
| Kingstowne-Sassafras-Neabsco complex, 2 to 7 percent slopes | 6K | Well drained | C | Somewhat limited | Very limited |
| Glenelg silt loam, 2 to 7 percent slopes | 6K | Well drained | B | Not limited | Somewhat limited |
| Wheaton-Glenelg complex, 15 to 25 percent slopes | 5K | Well drained | C | Very limited | Very limited |
| Glenelg silt loam, 25 to 45 percent slopes | 4K | Well drained | B | Very limited | Very limited |
| Urban land-Chantilly complex | 4K | Not rated | Not rated | ||
| Wheaton-Meadowville complex, 2 to 7 percent slopes | 4K | Well drained | C | Not limited | Very limited |
| Nathalie gravelly loam, 7 to 15 percent slopes | 3K | Well drained | B | Somewhat limited | Very limited |
| Codorus silt loam, 0 to 2 percent slopes, occasionally flooded | 3K | Somewhat poorly drained | B/D | Very limited | Very limited |
| Sassafras-Marumsco complex, 7 to 15 percent slopes | 3K | Well drained | B | Somewhat limited | Very limited |
| Urban land-Kingstowne complex | 3K | Not rated | Not rated | ||
| Grist Mill-Mattapex complex, 2 to 7 percent slopes | 3K | Well drained | C | Somewhat limited | Very limited |
| Sassafras-Marumsco complex, 25 to 45 percent slopes | 3K | Well drained | B | Very limited | Very limited |
What This Means
Building & Foundations
About 22% of soils have significant building limitations, while the rest are generally suitable. Check specific sites carefully — conditions vary across the area.
Septic Systems
About 58% 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.