Soil series profile
Collegedale soil series
Collegedale is a well drained soil with a silty clay loam surface, mapped on 164,340 acres in 21 counties in TN. Hydrologic group C.
- Drainage class
- Well drained 100% of mapped acres
- Hydrologic group
- C 98% of mapped acres
- Typical topsoil pH
- 5.0 very strongly acidic · range 5.0–5.3
- Mapped area
- 164k acres in 21 counties, 1 state
Typical Collegedale profile
Texture and pH by depth
Show as a table
| Depth | Texture | pH | Clay | Sand | Organic matter |
|---|---|---|---|---|---|
| 0–4 in (Ap) | Silty clay loam | 5.0 | 38% | 18% | 1.5% |
| 4–62 in (Bt) | Silty clay | 5.0 | 49% | 7% | 0.25% |

What this means
What Collegedale soil means for gardens, lawns and septic systems
For gardens
Typical topsoil in Collegedale soils is very strongly acidic: pH 5.0 (most land between 5.0 and 5.3). Most vegetables and lawn grasses do best around 6.0 to 7.0, so lime is often needed; blueberries, azaleas and rhododendrons like it as it is.
Loamy topsoil (loam, silt loam and similar) covers 98% of mapped Collegedale acres: generally the easiest soil to garden, holding moisture without staying waterlogged. The most common surface texture is silt loam (56% of mapped Collegedale acres).
100% of mapped Collegedale acres is moderately well to excessively drained, which suits most garden plants.
For lawns and yards
On 98% 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 Collegedale 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.
Where Collegedale soil is found
Mapped acres
Collegedale is mapped in Tennessee.
| County | Acres | Share of county land |
|---|---|---|
| Sullivan County, TN | 52,797 | 19.9% |
| Jefferson County, TN | 21,733 | 12.3% |
| Washington County, TN | 18,869 | 9.0% |
| Greene County, TN | 11,232 | 3.1% |
| Anderson County, TN | 10,817 | 5.0% |
| Hawkins County, TN | 8,999 | 2.9% |
| Campbell County, TN | 8,533 | 2.8% |
| Hamblen County, TN | 5,550 | 5.4% |
| Roane County, TN | 4,204 | 1.8% |
| Monroe County, TN | 4,176 | 1.0% |
| Blount County, TN | 4,050 | 1.2% |
| Knox County, TN | 3,485 | 1.1% |
| Polk County, TN | 3,184 | 1.1% |
| Hamilton County, TN | 2,089 | 0.6% |
| Meigs County, TN | 2,064 | 1.6% |
| Rhea County, TN | 1,270 | 0.6% |
| Grainger County, TN | 1,060 | 0.6% |
| Unicoi County, TN | 93 | 0.1% |
| Carter County, TN | 88 | 0.0% |
| Hancock County, TN | 32 | 0.0% |
| McMinn County, TN | 16 | 0.0% |
Septic absorption fields
NRCS rating, share of Collegedale acres
Show as a table
| Category | Share of acres |
|---|---|
| Not limited | 0.0% |
| Somewhat limited | 0.0% |
| Very limited | 100.0% |
Drainage, water table and flooding
Share of Collegedale acres
- Depth to seasonal high water table
- None reported within about 6.5 feet (median where reported).
- Flooding
- Not mapped as flooding on most acres.
- Slope
- Typically 9–27% (median 13%).
- Topsoil organic matter
- Median 1.5%.
Drainage class
Show as a table
| Category | Share of acres |
|---|---|
| Excessively drained | 0.0% |
| Somewhat excessively drained | 0.0% |
| Well drained | 100.0% |
| Moderately well drained | 0.0% |
| Somewhat poorly drained | 0.0% |
| Poorly drained | 0.0% |
| Very poorly drained | 0.0% |
Hydrologic soil group
Show as a table
| Category | Share of acres |
|---|---|
| A: fast infiltration (mostly sandy or gravelly) | 0.0% |
| B: moderate infiltration | 0.0% |
| C: slow infiltration | 97.6% |
| 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% |
| Not rated | 2.4% |
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 Collegedale (component kind "Series") in SSURGO: 164,340 acres.
- Method
- Shares are by mapped acres of Collegedale components. The profile comes from the single largest Collegedale component. Full methodology.