Charles Mix County, SD Shrink-Swell Risk
Charles Mix County, SD's soil, for shrink-swell risk
Moderate
Charles Mix County, SD: USDA's soil survey rates 74% of the county "Moderate" for shrink-swell potential (4.38% linear extensibility). Conventional foundations are the reasonable expectation here, with routine moisture-control practice rather than special engineering.
What Charles Mix County's reading doesn't cover
Two lots a mile apart in Charles Mix County can carry different soil, even though they share one countywide reading. A local geotechnical report, typically $1,000-$5,000 (around $2,700 typical), is the only way to know what one lot in Charles Mix County will actually do.
What it costs to find out, versus to ignore it
With Charles Mix County, SD rating "Moderate", a geotechnical report is still worthwhile before a build, just less urgent than in a high-risk county. A geotechnical report runs $1,000-$5,000, typically around $2,700. Foundation repair, if a specific lot turns out to differ from the county average, runs $5,000-$15,000.
Charles Mix County's rank among South Dakota counties
Nationally, Charles Mix County, SD is the 419-most-constrained of 3,085 rated counties for shrink-swell soil. Within South Dakota alone it ranks 28 of 66. Charles Mix County covers 1,097 square miles and counts 9,343 residents.
See how another county compares
Orleans Parish, LA carries this site's most-constrained reading. Jones County, NC and Kemper County, MS are worth a look for comparison.
How this reading is built, and its real limits · Moisture management: the cheap fix that works on any soil
More of South Dakota
Every county in South Dakota is on this site, including Clark County, SD and Harding County, SD. The full underlying dataset is downloadable directly, one row per county.