Sinkhole risk in James City County, VA: Mostly deep or small

Mostly deep or small

Some soluble rock, mostly deeply buried or in a small share of the county.

On soluble rock: 10%
At or near the surface: 10%
Buried under cover: 0%

The next step for one property

Sinkholes are uncommon here; watch for new depressions after heavy rain or leaking pipes.

That works out to roughly 15 of James City County's 142 square miles on soluble rock, 15 of them with the rock at or near the surface. With about 82,797 residents (582 per square mile), most of the county is built up, so a mapped unit is likely to sit under somebody's street. The figures come from 520 map points about 0.5 miles apart, so a pocket smaller than that can be missed or overstated.

Two things to read before deciding: how these percentages are measured, and the warning signs that apply anywhere.

Counties around James City County

The nearest county rated sinkhole country is Hertford County, NC, about 67 miles south. 5 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

Williamsburg city, VA 5 mi southeast · 4% at surface
Gloucester County, VA 15 mi east · 8% at surface
Surry County, VA 15 mi south · 7% at surface
Charles City County, VA 15 mi west · 5% at surface
New Kent County, VA 18 mi northwest · 22% at surface
York County, VA 22 mi east · 5% at surface

Which formation it is

The largest mapped soluble unit here is the Chesapeake Group (sand), Tertiary in age, covering about 10% of the county.

Against the rest of Virginia

James City County ranks 56 of 133 in Virginia for soluble rock at the surface, and sits above 68% of US counties on that measure.