Sinkholes and Former Quarries in St. Louis

Sinkholes are back in the news, with photos of homeowners standing in front of muddy water-filled holes and being interviewed by reporters.

The city has been open about the state of St. Louis’ infrastructure, many of which date back to the 19th Century. Add in the deterioration of cast iron pipes, and droughts that cause dirt to shrink, and you have the recipe for sewer and water main breaks.

However, the history of the ground beneath our feet shows that the aging infrastructure is not the only factor in the sinking and subsidence surrounding St. Louis. If you are looking for property to purchase in St. Louis, these modern and historical methods will help you see below the surface to find potential new homes and businesses.

For example, all good St. Louis realtors will scope the sewer lateral from the house to its sewer main at the back. The sewer lateral used to be made from terracotta clay pipes that were connected in 1- to 2-foot sections. As you would expect, these segments of clay pipes can separate or loosen over time, which could threaten the safe passage and disposal of sewage from your house. The buyer can rest assured that the seller will not make costly repairs if he or she has the sewer lateral scoped by a professional before buying a house. (For example, I spent $175 to scope my sewer lateral before I bought my house. It revealed that clay pipes needed $6,500 worth of repairs. The seller paid the cost before I closed.

Prospective buyers should not only use a scope but also consult the 1876 Compton and Dry View of St. Louis. Although the city was more than 100 years old at the time of the topographical survey, most of the area now inhabited was undeveloped farmland or countryside. Compton and Dry provide important information on why a sinkhole may be opening today. It is most striking that much of south St. Louis was built on more than a flat prairie. Street grading is what created the city’s topography. This was done to smoothen the bumps and dips in the earth’s surface and replace them with gentle inclines calculated by surveyors. This long-ago task becomes most evident when it rains, and puddles appear in seemingly unlogical places.

Street grading cannot hide the fact that a lot of south St. Louis’s buildings are built on karst topography. Merriam Webster describes it as “an irregular limestone area with sinkholes and underground streams and caverns”. This is a horrible place to build a city if you’re not careful.

The United States Geological Survey has this piece of helpful advice: “Knowing the location of karst features could help city planners and individual landowners make decisions about where to build houses or other structures.” This information could help cities save thousands on repairs to buildings built on unstable karst terrain.

It would have been a shame if the South St. Louis developers had not heeded this wise advice.

You might see one or more houses that are leaning insecurely while walking around Benton Park West or Benton Park West. If you see only one or two houses in this situation, it is usually a sign that a sinkhole has been improperly filled in. This could be because underground rivers that run through the karst limestone formations have not become dormant. Prospective buyers should consult Compton and Dry to determine if the potential purchase is on top of a sinkhole.

In a similar vein, the threat from former quarries is also present. Many of these sinkholes were likely created by people who wanted to get easy access to limestone outcropping. You can identify houses built on former quarries by the presence of collapsing or sinking buildings in groups. Utah Street, in Benton Park West, is home to several abandoned brick houses that appear to be doomed.

Many quarries were filled in by ranches and Cape Cod-style homes in the city’s outer reaches after the war housing crunch. If there is a strangely anachronistic mix of older and newer architecture in the neighborhood, potential homeowners should be cautious about buying houses.

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