Septic soil in Platte County, MO, by the numbers
Very limited
84.1% of Platte County, MO's surveyed soil comes back "Very limited" in USDA's own SSURGO data, the county's dominant condition for a septic absorption 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. Platte County, MO is 419.823 square miles with a population of 113,207.
What Platte County's reading doesn't cover
Platte County's rating is an average across the whole county, not a promise about any one lot inside it. A local percolation test, typically $750-$1,850 (around $1,300 typical), is the only way to know what one lot in Platte County will actually do.
What a system would cost here
With 84.1% of Platte 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.
How Platte County, MO compares
Nationally, Platte County, MO is the 1,767-most-constrained of 3,058 rated counties for septic soil. Within Missouri alone it ranks 95 of 114.
Related guides
How this rating is built, and its real limits · Conventional vs. engineered septic systems