Septic soil in Caledonia County, VT, by the numbers
Very limited
In Caledonia County, VT, 96.1% of the surveyed land carries a "Very limited" rating for a standard septic drain field. That reading means a conventional system is a poor bet here - 96.1% of Caledonia County lands in the strictest "very limited" bucket USDA uses. Caledonia County, VT is 649.214 square miles with a population of 30,535.
What Caledonia County's reading doesn't cover
USDA's survey covers the whole of Caledonia County, VT 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 Caledonia County will actually do.
What a system would cost here
With 96.1% of Caledonia 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.
Where this sits nationally
Nationally, Caledonia County, VT is the 512-most-constrained of 3,058 rated counties for septic soil. Within Vermont alone it ranks 4 of 13.
Further reading
How this rating is built, and its real limits · Conventional vs. engineered septic systems