Learn the Ropes of Manhole Safety

Developing a high comfort level and failing to set up a safety zone around open manholes can lead to disaster.

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Before any of us worked around sewers and storm drains, we hardly gave a second thought to manhole covers in the street. But a funny thing happens when you enter the world of pipeline cleaning, inspection and rehabilitation: you begin to notice every manhole cover.

Suddenly, a world that was once completely invisible comes to life. You begin to identify the markings on manhole covers as being either sewer or a storm drain and find great pleasure in sharing this knowledge with others. Even on a family outing at Disneyland, you can’t help but spot the manholes and boastfully point them out to your wife and kids.

Collection system personnel in particular become very familiar with manholes. Since their primary job is to keep the sewers flowing, much of the work they perform requires access through a manhole. Whether it’s inserting a nozzle in order to clean a pipeline, or introducing a camera to inspect it, you remove manhole lids numerous times throughout the day.

Manhole depths can differ greatly, especially in areas where topographical elevations vary. Some can be very shallow and only extend a couple of feet underground, while others reach depths of 50 feet or more. They are very important structures that allow critical maintenance on our pipelines, but they are also very dangerous both to the individuals working around them and pedestrians walking near them.

Open manholes

During cleaning, inspection or rehabilitation work, manholes must be left open in order to facilitate access to the pipelines below. Because of the nature of the work, they are sometimes left open for extended periods of time. Working around these open chasms becomes so natural that few seasoned workers give it a second thought.

But open manholes are dangerous and can pose a serious hazard. One careless misstep can have catastrophic consequences. A worker who accidently steps into a 24-inch manhole could easily break a leg. A smaller person or even a child might not be so lucky. A 36-inch manhole opening is a whole different story. Accidently stepping into an open manhole of this size could be fatal. Because of its large diameter, there is nothing to keep someone from falling straight to the bottom.

The possibility of falling into a large trunk line sewer with heavy flow is of even greater concern. Some trunk lines are very large and carry a significant volume of wastewater. It’s not uncommon to see 60-inch or larger trunk lines carrying thousands of gallons per minute and flowing at speeds in excess of 5 feet per second. Falling into a manhole under these conditions will carry an individual away with little chance for survival.

Manholes can also be dangerous for pedestrians. Open manholes are a natural curiosity to those who have never seen them, and children are an ever-present danger. Curiosity will draw them for a look inside. But unlike adults who tend to stand back a foot or two while bending over to look in, children have no fear and will walk right up, some even with their toes hanging over the edge. Just one misstep or a slight push from a child behind could result in a complete catastrophe. Can you image what it would look like to have every local television station leading with this story while your company or agency name is plastered across the screen as the culprit?

Safety must be the highest priority for every crewmember working in and around manholes.

Worker safety

Working around open manholes requires strict communication rules. It begins by notifying each individual that the manhole has been opened and is now a potential hazard. This awareness will alert coworkers that they must be careful of where they step and that they need to be alert and aware of unauthorized individuals entering the work area.

Communication is critical for the safety of the workers. Noise from surrounding traffic and running equipment can make it difficult to hear, so physical communication must be incorporated in order to make coworkers aware of your movements. It may be necessary to make sure coworkers know when you intend to step within their personal space. An unintentional bump could knock someone into the manhole, but clear communication will ensure that a safe working environment is maintained and unintentional collisions are avoided.

Pipeline inspection, line cleaning and rehabilitation all involve tasks that take individuals away from the manhole opening itself. These are the times when bystanders are able to approach without being shielded from the danger. Ideally, there should always be someone protecting the manhole, but that isn’t always possible or practical.

Manhole barriers

At this time, there is no legislation that requires manhole safety devices. Most companies and agencies do not require any type of protective barriers. Perhaps though, it is time to begin looking seriously at making open manholes safer, and there are some physical barriers that achieve that goal.

Manhole safety barriers have been around for many years. These devices are like fences and provide a protective barrier around the manhole. They have three sides and provide 270 degrees of protection, or 360-degree protection when chains are used to close off the open end.

A manhole safety barrier is not perfect, but is certainly superior to having nothing at all. It does provide a warning and keeps bystanders a safe distance away. Its major drawback is the fact that it is heavy and difficult to store. Some of the older models were made of steel and were extremely heavy, but many newer models are made of aluminum and are much lighter. Still, they are large, bulky and difficult to store on vehicles.

Safety manhole covers are devices that have gained popularity in recent years. They provide a mesh that lies over the top of the manhole, but still allows cable from a CCTV camera or hose from a jetter to enter the line. This device also doubles as a top-hole roller. Because of its design, this product is perhaps more ideal for the pipeline cleaning and inspection industry.

If a manhole protection device is not available, a protection barrier can still be created with traffic cones. Placing cones side by side around the circumference of the manhole opening creates a visual barrier, and even though this method does not provide a physical restraint, it will still keep most people from stepping too close to the open manhole. By placing cones at least 2 feet back from the manhole rim, you establish a safety circumference that will ensure bystanders remain outside the danger zone, even when they bend over to look in.

Unfortunately, some people will not be deterred by the cones and will still step over them in an effort to get a closer view. In this case, there is no substitute for vigilance and verbal warnings.

Manhole safety must be taken very seriously. While incorporating some of these suggestions will help minimize the hazard that an open manhole poses and help eliminate the potential for catastrophe, there is no substitute for training and awareness of safety procedures around open manholes.



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