Bitumen is wonderful stuff. Oily, black, naturally-occurring, humans have been mixing it with other materials and putting it to good use for centuries. Also known as tar or asphalt, it’s really useful for waterproofing homes and paving roads.
Recently while walking I noticed a hole in the asphalt near the corner of H Street and Vermont Avenue. I reported it. A few days later I came back and measured the depth of the hole. It was 3.5 feet deep.
Some might call that formation – caused by a drainage system failure or standing water – a pothole.
I thought of it as a sinkhole.
Sink holes are natural depressions in the earth’s surface.
They occur most often in areas of karst terrain. In these areas, the rocks beneath the surface are carbonates such as limestone which are highly soluble and very susceptible to any form of precipitation or flow from underground drainage systems, whether natural or manmade.
Sinkholes have been in the news recently. In February a sinkhole opened beneath a house in Florida and killed a man. Such events highlight the need for a detailed and accurate mapping system to better determine the distribution of soluble rock in the United States. The system would provide education and provide a data base network, helping state and local land-use planners determine areas where sinkholes might develop.
Sink holes can range in size from 1 to 600 meters (3.3 to 200ft) both in diameter and depth.
With development increasing and with sinkhole terrains underlying 20 percent of our country, including areas of Florida, Texas, Alabama, Missouri, Kentucky, Tennessee, Pennsylvania it is important to know more about sinkholes.
Even here in Washington D.C., we have areas identified as potentially hazardous. That little sinkhole at the corner of H Street and Vermont Ave. NW is just a reminder that we need a better understanding of what is going on beneath our feet.
Let’s get started today in properly identifying and mapping areas in the United States that are currently susceptible in developing into sink holes. Without adequate solid rock we may be all at risk! We can save lives just by what we do today!
