5/4/2004: Sinkhole eats car

[wolf]

Pennsylvania is extremely good at sinkholes. Much of the southeastern portion of the state is Karst Topography. The whole area is underlain by limestone. Mild acids in underground water react with the limestone and it basically just fizzes away, albeit slowly. Eventually there isn't anything supporting the soil and the whole thing just drops. (my undergraduate degree is in Geography and Planning. We were all over this geomorphology stuff.)

One disrupted the expansion of route 202 at King of Prussia. They had to fill it first. The relevant article is about 2/3 of the way down the page, headined "Massive Highway Improvements Garner Governor's Praise." It notes that they had to pump 1.4 million cubic FEET of pressure injected grout into the holes. That's a lot of freaking grout. They had to build a grout manufacturing plant at the site, I believe.