Vermilion County, IL's soil, for a septic absorption field
Very limited
In Vermilion County, IL, 98.8% of the surveyed land carries a "Very limited" rating for a standard septic drain field. This is the reading that pushes a project toward an engineered system rather than a conventional one, and it covers 98.8% of Vermilion County's land. Vermilion County, IL is 898.32 square miles with a population of 71,106.
What Vermilion County's reading doesn't cover
Two lots a mile apart in Vermilion 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 Vermilion County will actually do.
What a system would cost here
With 98.8% of Vermilion 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, Vermilion County, IL is the 115-most-constrained of 3,058 rated counties for septic soil. Within Illinois alone it ranks 6 of 101.
Related guides
How this rating is built, and its real limits · Conventional vs. engineered septic systems