Washington County, Tennessee
The most common soil here is Dewey, on about 27% of the land: a silt loam, smooth, like flour. Collegedale and Montevallo come next.
About 85% of the land drains well.
USDA rates 65% of the land very limited for a standard septic drain field, and 68% very limited for homes with basements. That means extra cost or special design, not that it can't be done.
Worth knowing: 6% of the land floods occasionally or more, and bedrock lies within 40 inches under 20% 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 soils you're most likely standing on
The biggest named soils in Washington County, Tennessee, each drawn five feet deep from its official USDA description, in its recorded colors.
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 Well drained and the dominant hydrologic group is B (moderate infiltration). The most common soil order is Ultisols — strongly weathered soils with clay-enriched subsoils, common in warm humid climates. 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 Washington County, Tennessee. 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 |
|---|---|---|---|---|---|
| Dewey-Collegedale complex, 6 to 15 percent slopes, severely eroded | 40K | Well drained | B | Somewhat limited | Somewhat limited |
| Dewey-Collegedale complex, 15 to 25 percent slopes, severely eroded | 29K | Well drained | B | Very limited | Very limited |
| Dewey-Udorthents-Urban land complex, 5 to 20 percent slopes | 16K | Well drained | B | Very limited | Very limited |
| Greendale silt loam, 0 to 6 percent slopes, rarely flooded | 10K | Well drained | B | Very limited | Somewhat limited |
| Bowmantown silt loam, 6 to 12 percent slopes | 8K | Moderately well drained | C | Very limited | Very limited |
| Unicoi-Rock outcrop complex, 50 to 80 percent slopes | 6K | Somewhat excessively drained | D | Very limited | Very limited |
| Urban land-Udorthents complex | 6K | Not rated | Not rated | ||
| Talbott-Rock outcrop-Bradyville complex, 12 to 20 percent slopes, eroded | 5K | Well drained | C | Very limited | Very limited |
| Montevallo channery silt loam, 35 to 50 percent slopes | 4K | Well drained | D | Very limited | Very limited |
| Montevallo channery silt loam, 50 to 80 percent slopes | 4K | Well drained | D | Very limited | Very limited |
| Cataska channery silt loam, 50 to 80 percent slopes | 4K | Excessively drained | D | Very limited | Very limited |
| Montevallo channery silt loam, 12 to 20 percent slopes | 4K | Well drained | D | Very limited | Very limited |
| Lindside silt loam, 0 to 3 percent slopes, occasionally flooded, warm | 4K | Moderately well drained | C | Very limited | Very limited |
| Talbott-Rock outcrop-Bradyville complex, 20 to 50 percent slopes, eroded | 3K | Well drained | C | Very limited | Very limited |
| Dewey-Collegedale complex, 25 to 40 percent slopes, severely eroded | 3K | Well drained | B | Very limited | Very limited |
| Waynesboro loam, 6 to 15 percent slopes, eroded | 2K | Well drained | B | Somewhat limited | Somewhat limited |
| Water 1982 NRI | 2K | Not rated | Not rated | ||
| Nolichucky loam, 5 to 12 percent slopes, eroded | 2K | Well drained | B | Somewhat limited | Somewhat limited |
| Keener loam, 5 to 12 percent slopes | 2K | Well drained | B | Somewhat limited | Very limited |
| Northcove stony sandy loam, 50 to 80 percent slopes | 2K | Well drained | A | Very 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.
What This Means
Building & Foundations
About 68% of soils are rated "very limited" for dwellings with basements. Specific challenges include shallow bedrock, steep slopes, flood-prone areas. A geotechnical assessment is recommended before building.
Septic Systems
About 65% 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.