What Carroll County, VA's soil rates for a septic system
Very limited
Soil across 75.3% of Carroll County, VA rates "Very limited" in USDA's septic-absorption-field interpretation. A standard gravity system routinely fails on ground like this; the same share of the county falls in USDA's worst absorption-field bucket outright. Carroll County, VA is 474.742 square miles with a population of 29,242.
What Carroll County's reading doesn't cover
This is a countywide, area-weighted figure across every soil survey map unit in Carroll County, VA - never a reading for one specific parcel. A local percolation test, typically $750-$1,850 (around $1,300 typical), is the only way to know what one lot in Carroll County will actually do.
What a system would cost here
With 75.3% of Carroll 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.
Carroll County's rank among Virginia counties
Nationally, Carroll County, VA is the 2,263-most-constrained of 3,058 rated counties for septic soil. Within Virginia alone it ranks 56 of 110.
Further reading
How this rating is built, and its real limits · Conventional vs. engineered septic systems