Buchanan County, IA's soil, for a septic absorption field
Very limited
In Buchanan County, IA, 99% 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 99% of Buchanan County's land. Buchanan County covers 571.084 square miles and counts 20,733 residents.
This is a county figure, not a parcel figure
Nothing about Buchanan County, IA's SSURGO figure applies to a specific address - it's a county-wide average. A site-specific perc test, usually $750-$1,850, is what a health department will actually require before permitting a lot in Buchanan County.
System cost, conventional vs. engineered
Given Buchanan 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, Buchanan County, IA is the 93-most-constrained of 3,058 rated counties for septic soil. Within Iowa alone it ranks 4 of 99.
Related guides
How this rating is built, and its real limits · Conventional vs. engineered septic systems