Sinkhole risk in Sumner County, TN: Sinkhole country

Sinkhole country

Soluble rock at or near the surface across much of the county.

On soluble rock: 70%
At or near the surface: 70%
Buried under cover: 0%

The next step for one property

Get a sinkhole or geotechnical inspection before buying, building or adding weight to a foundation.

That works out to roughly 371 of Sumner County's 529 square miles on soluble rock, 371 of them with the rock at or near the surface. With about 211,721 residents (400 per square mile), homes are spread across towns and farmland, and a mapped unit may or may not reach the developed parts. The figures come from 253 map points about 1.4 miles apart, so a pocket smaller than that can be missed or overstated.

Two things to read before deciding: the signs to look for and how an inspection works, and how these percentages are measured.

Counties around Sumner County

The closest county with no soluble rock mapped is Hopkins County, KY, about 83 miles northwest. 5 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

Trousdale County, TN 18 mi east · 85% at surface
Simpson County, KY 20 mi north · 99% at surface
Robertson County, TN 23 mi west · 92% at surface
Wilson County, TN 24 mi southeast · 94% at surface
Allen County, KY 24 mi northeast · 51% at surface
Macon County, TN 26 mi east · 24% at surface

What Sumner County is built on

The largest mapped soluble unit here is the Ordovician [units] including Richmond Group (which includes Mannie Shale, Fernvale Limestone, Sequatchie Formation, and Arnheim Formation), the Maysville Group (which includes Leipers Formation), the Eden Group (which includes Inman Formation), and (shale), Ordovician in age, covering about 29% of the county. Next is the St. Louis Limestone and Warsaw Limestone at 25%.

Against the rest of Tennessee

Sumner County ranks 32 of 95 in Tennessee for soluble rock at the surface, and sits above 93% of US counties on that measure.