Septic suitability in Logan County, KS
Somewhat limited
Logan County, KS's SSURGO dominant class comes back "Somewhat limited", covering 71.6% of the county. Modification usually rescues a conventional system at this rating - added fill or a larger field - rather than forcing a full engineered redesign. The county spans 1,072.993 square miles, home to 2,694 people.
What this number does and doesn't tell you
USDA's survey covers the whole of Logan County, KS at once, not any single address. Budget $750-$1,850 for a real perc test on any specific parcel - that's the only figure a permit application accepts.
Logan County: conventional vs. engineered cost
71.6% of Logan County carrying a "Somewhat 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.
Logan County's rank among Kansas counties
Among the 3,058 rated counties on this site, Logan County, KS ranks 3,021 most-constrained nationally, and 100 of 105 within Kansas.
Further reading
How this rating is built, and its real limits · How a percolation test actually works