Where do we go from here?

Now that I've established the thinking for the beginning of the story, let me give you some pictures, just for fun:

I've been involved in one aspect or another of engineering geology for over 15 years now. I've collected a few photos, and want to share them with you, and perhaps get YOUR thoughts and impressions.

The first photo here is of a sinkhole that opened up at the Wal-Mart store in Columbia, Missouri in June, 2005. Luckily, no one was hurt. It was caused by a break in an underground galvanized corrugated metal pipe, and the soil around it washed away during a 4" rain event. It DID, however, do serious damage to the outdoor lawn and garden center at the Wal-mart. I don't know if there was a sudden increase in sales at Home Depot's lawn and garden center as a result, but it's an interesting postulate to make that the collapse had some effect other than the property damage that occurred.

This next image is of a crater, not a sinkhole, that was caused from ABOVE, when a propane truck blew up on Route 6 in Utah, this past year. When natural gas explodes, it does so in two steps. First, it evaporates and fills up the air space around it rapidly. THEN, it ignites. This phenomenon is called a BLEVE (prounounced 'blev-ee", and rhymes with 'levee", short for "Boiling Liquid Expanding Vapor Explosion" . The sheer SIZE of this crater is amazing to me, and I copied it off of CNN.

Sinkholes and craters- these are two of the things that engineering geologists are interested in....and believe me, I've seen my share. These are two examples of what has been considered by other geologists in the category of "man-induced land subsidence". Underground utility breaks are fairly common, and depending upon the utility, can create big subsidences that swallow things. The explosively-induced crater is unusual, in that normally it's caused by a gas main BELOW the sinkhole that's created, not cratered from above.

There are other examples, too....man-induced land subsidence includes collapse of abandoned underground mine land. You get all kinds of problems from abandoned mines.

Until next time,

Trenchless Geologist