What Fentress County, TN's soil rates for a septic system
Very limited
76.1% of Fentress County, TN's surveyed soil comes back "Very limited" in USDA's own SSURGO data, the county's dominant condition for a septic absorption field. This is the reading that pushes a project toward an engineered system rather than a conventional one, and it covers 76.1% of Fentress County's land. Fentress County, TN is 498.607 square miles with a population of 20,129.
What Fentress County's reading doesn't cover
USDA's survey covers the whole of Fentress County, TN at once, not any single address. A local percolation test, typically $750-$1,850 (around $1,300 typical), is the only way to know what one lot in Fentress County will actually do.
What a system would cost here
With 76.1% of Fentress County rating "Very limited", a standard gravity system is not a safe assumption here. The engineered-system range, $10,000-$40,000 (mound or aerobic treatment), is the more realistic number to plan around, against $3,000-$8,000 for a conventional system on the rare lot that passes.
How Fentress County, TN compares
Nationally, Fentress County, TN is the 2,229-most-constrained of 3,058 rated counties for septic soil. Within Tennessee alone it ranks 66 of 95.
Further reading
How this rating is built, and its real limits · Conventional vs. engineered septic systems