Have you ever wondered why manhole covers are round? There are plenty of shapes that could have been chosen for manhole covers, so why a circle?
Well, according to the book, Ask a Science Teacher by Larry Scheckel, there are a few reasons why these covers are round. In this post, we’ll take a look at his explanations and then answer a few other questions about manhole maintenance and repair.
Why Does Scheckel Think Manholes Are Round?
Read through the following reasons that Scheckel thinks manholes are round. Do you agree with them?
• Manholes are round to “resist the compression of Earth around it.”
• Round accessories are easier to manufacture than rectangles or square.
• When something is round and heavy, it’s easier to move than other shapes.
• Installation goes faster because plumbers don’t have to match angles. The round design makes it easy for the covers to slip right in place.
• Circular covers can’t fall through the opening.
This last point is probably the most important for commercial property owners because it means that the circular design prevents damage to the cover. Whenever a manhole is created, there is a lip around the hole’s rim. This lip holds the cover in place. In order for this to happen, the underlying hole has to be smaller than its cover. Because round covers can’t be installed incorrectly, there’s no chance of the cover falling into the hole. This isn’t the case with either rectangle or square shapes. If the cover’s installed at an angle, even slightly, this could cause the cover to fall into the hole and cause damage.
A missing manhole cover as the result of falling into the hole isn’t just a cosmetic problem and it doesn’t just damage underground sewer pipes. If you have a cover that suddenly falls below the surface, this spells bad news for pedestrians and drivers who aren’t paying attention. Yikes!
So, there you have Scheckel’s explanation for why manhole covers are round. Now, let’s talk about why manhole covers are important for your underground pipes.
Manhole Thefts Are on the Rise
You might wonder why someone would want to steal manhole covers. Monetary gain is usually the #1 reason for thievery and manhole covers are no exception. The simple fact is that manhole covers can be recycled for money, which makes them enticing for people looking to score a little extra cash. However, if you have missing covers on your property this leaves your underground sewer pipes exposed and accessible to anyone. It also puts you in a position for being liable should someone accidentally fall in the hole.
Those two reasons are why it’s important to take extra precautions to ensure manhole protection. So, what can a utility service do to keep their covers in place? Here are a few suggestions.
Some municipalities have started welding their covers to stop thievery. However, this might not be the most cost-effective solution if sewer contractors need to gain access to the manhole. You’ll have to go through the expense of hiring someone to break the welded seal.
Bolt in Place
A better solution could be bolting the cover in place using a 5/8-inch hex-head bolt. The bolt works well with a standard locking head and is a great deterrent. Why? Well, you might think a bolt is easy to remove with the right tools, but that’s exactly the point. Most thieves don’t have a 5/8 Allen wrench handy to remove a bolted manhole cover.
Consider Installing Plastic Manhole Covers
While plastic manhole covers aren’t standard in the United States, the U.K. has been using plastic covers in an attempt to prevent manhole cover robberies. The country decided to start using plastic covers because they don’t have any scrap value since there’s no metal in them.
Install a GPS Tracker
This might seem a bit extreme, but if you’re constantly getting targeted by scrap metal thieves, a bug can help you track down your covers. At the very least, develop relationships with recycling centers in the area and notify them when covers go missing.
Preventing manhole cover theft saves municipalities money and keeps the public safe. So, take whatever precautions necessary to make sure nothing goes missing on your watch!
Do you need to make manhole repairs? If so, contact Street Works Engineering. We’re available 24/7 for all emergency commercial plumbing and street work services. Call us at (888) 377-4002.