DeKalb County's SSURGO septic rating
Very limited
DeKalb County, TN's SSURGO dominant class comes back "Very limited", covering 70.5% of the county. This is the reading that pushes a project toward an engineered system rather than a conventional one, and it covers 70.5% of DeKalb County's land. For scale: 304.432 square miles and 21,747 people call DeKalb County home.
Before you rely on this for one lot
Nothing about DeKalb County, TN's SSURGO figure applies to a specific address - it's a county-wide average. The real answer for one lot is still a site-specific perc test, running about $750-$1,850 (typically near $1,300).
Budgeting for a system in DeKalb County, TN
DeKalb County's soil reading pushes the likely outcome toward an engineered system rather than a conventional one. Conventional systems run $3,000-$8,000 where they pass; where they don't, engineered alternatives (mound or aerobic treatment, whichever the health department requires) run $10,000-$40,000 - budget toward the higher figure until a perc test says otherwise.
Where this sits nationally
Among the 3,058 rated counties on this site, DeKalb County, TN ranks 2,443 most-constrained nationally, and 77 of 95 within Tennessee.
Further reading
How this rating is built, and its real limits · Conventional vs. engineered septic systems