Addison County, VT's soil, for a septic absorption field
Very limited
In Addison County, VT, 82.7% of the surveyed land carries a "Very limited" rating for a standard septic drain field. Practically, that rules out a simple gravity system for most of the county - 82.7% of it sits in USDA's most-constrained bucket. Addison County, VT is 766.332 square miles with a population of 38,047.
What Addison County's reading doesn't cover
Two lots a mile apart in Addison County can carry different soil, even though they share one countywide rating. A local percolation test, typically $750-$1,850 (around $1,300 typical), is the only way to know what one lot in Addison County will actually do.
What a system would cost here
With 82.7% of Addison 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.
Addison County's rank among Vermont counties
Nationally, Addison County, VT is the 1,879-most-constrained of 3,058 rated counties for septic soil. Within Vermont alone it ranks 11 of 13.
Related guides
How this rating is built, and its real limits · Conventional vs. engineered septic systems