Atchison County, KS: the USDA septic-suitability picture
Very limited
Atchison County, KS's SSURGO dominant class comes back "Very limited", covering 94.9% of the county. This is the reading that pushes a project toward an engineered system rather than a conventional one, and it covers 94.9% of Atchison County's land. The county spans 431.174 square miles, home to 16,249 people.
What this number does and doesn't tell you
This is a countywide, area-weighted figure across every soil survey map unit in Atchison County, KS - never a reading for one specific parcel. Budget $750-$1,850 for a real perc test on any specific parcel - that's the only figure a permit application accepts.
Atchison County: conventional vs. engineered cost
94.9% of Atchison County carrying a "Very limited" reading changes the realistic budget here. Conventional systems run $3,000-$8,000 where they pass; where they don't, engineered alternatives (mound or aerobic treatment, whichever the health department requires) run $10,000-$40,000 - budget toward the higher figure until a perc test says otherwise.
Where this sits nationally
Among the 3,058 rated counties on this site, Atchison County, KS ranks 678 most-constrained nationally, and 35 of 105 within Kansas.
Further reading
How this rating is built, and its real limits · Conventional vs. engineered septic systems