What Carbon County, UT's soil rates for a septic system
Very limited
In Carbon County, UT, 73.9% of the surveyed land carries a "Very limited" rating for a standard septic drain field. 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. Carbon County covers 1,479.343 square miles and counts 20,613 residents.
This is a county figure, not a parcel figure
This is a countywide, area-weighted figure across every soil survey map unit in Carbon County, UT - never a reading for one specific parcel. A site-specific perc test, usually $750-$1,850, is what a health department will actually require before permitting a lot in Carbon County.
System cost, conventional vs. engineered
Given Carbon County's rating, plan for the engineered-system range rather than the conventional one. 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, Carbon County, UT is the 2,334-most-constrained of 3,058 rated counties for septic soil. Within Utah alone it ranks 17 of 28.
Before you act on this
How this rating is built, and its real limits · Conventional vs. engineered septic systems