Sully County, SD Shrink-Swell Risk

Sully County, SD's soil, for shrink-swell risk

Moderate

Sully County, SD: USDA's soil survey rates 78.9% of the county "Moderate" for shrink-swell potential (4.68% linear extensibility). A real but modest amount of movement - standard foundations usually hold up, but drainage and moisture control around the foundation still matter more than on low-risk soil.

What Sully County's reading doesn't cover

Two lots a mile apart in Sully County can carry different soil, even though they share one countywide reading. A site-specific soil report, usually $1,000-$5,000, is what an engineer would actually pull before designing a foundation on a lot in Sully County.

What it costs to find out, versus to ignore it

With Sully 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.

Sully County's rank among South Dakota counties

Nationally, Sully County, SD is the 353-most-constrained of 3,085 rated counties for shrink-swell soil. Within South Dakota alone it ranks 23 of 66. Sully County covers 1,007 square miles and counts 1,468 residents.

For contrast

Orleans Parish, LA carries this site's most-constrained reading. Lee County, IA and Hyde County, NC 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 Bennett County, SD and Lincoln County, SD. The full underlying dataset is downloadable directly, one row per county.