Sinkhole risk in Richmond County, NY: No soluble rock mapped

What to do about a house in Richmond County

No soluble bedrock is mapped here, so natural sinkholes are unlikely. Collapses from broken pipes or old mines are a separate risk.

Across 58 square miles, under one square mile of Richmond County maps onto soluble rock. With about 498,212 residents (8,661 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 500 map points about 0.3 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 Richmond County

The nearest county rated sinkhole country is Union County, PA, about 155 miles west. 6 of the 6 closest counties land in the same band, so this is a regional pattern rather than a local quirk.

• Kings County, NY 11 mi northeast · 0% at surface
• Union County, NJ 11 mi northwest · 0% at surface
• Hudson County, NJ 12 mi north · 0% at surface
• Middlesex County, NJ 16 mi southwest · 0% at surface
• Essex County, NJ 17 mi north · 0% at surface
• Queens County, NY 17 mi east · 0% at surface

Against the rest of New York

Richmond County ranks 45 of 62 in New York for soluble rock at the surface, and sits above 0% of US counties on that measure.

• New York County under 1%
• St. Lawrence County under 1%
• Saratoga County under 1%
• Cayuga County under 1%
• Clinton County under 1%