Modern equipment and technology are giving utility workers a huge helping hand when it comes to safe digging. But there still is no substitute for thorough project planning and communication, worker training, and an overall commitment to jobsite safety.
And with April recognized as National Safe Digging Month, there’s no better time to reinforce the importance of following proper procedures before putting a shovel, drill, or bucket, into the ground.
The following is a summary of essential safety steps when installing or servicing underground utilities.
Locate with confidence
The first rule of digging is always to call 811. That said, even though 811 "Call Before You Dig" is a national program by the Common Ground Alliance, each state has its own laws governing how the program works. So, in reality, the first step to safe digging is understanding where you are working and what the “Call Before You Dig” law requires.
Another safety measure that goes hand in hand with calling 811 is a technique known as white lining. That’s when the contractor marks their intended bore path so the utility owners understand what needs to be located and potholed (aka daylighted).
Once the known utilities have been marked, it’s best practice for a contractor to validate those locates.
“A big misconception is that if there is no paint in the area, there are no utilities in the area,” says Rodolfo Cabello, Product Marketing Manager, Utility Locating at Subsite Electronics. “We always recommend contractors have a utility locator on their jobsite. If you think something is going to be along your intended bore path, or even close to it, why not make sure?”
Using a good multi-frequency locating system will allow transmission of a range of frequencies from 253 Hz to 200 kHz. “That will give you a good enough signal to get a confident locate with depth information,” Cabello points out. If there could be utilities that aren’t made of metal, such as plastic water lines, locate beacons could help.
“If you have no idea where the utilities could be, a GPR (ground-penetrating radar) locator will likely be needed,” Cabello adds. “GPR can also help you locate abandoned utility lines that may have been made of copper.”
Speaking of hard-to-find lines, don’t forget about private lines that may have never been marked in the first place. In addition to state-based 811 laws, there is an OSHA regulation that requires contractors to locate any other utilities that could reasonably exist on a property. That’s important because the 811 system only covers publicly owned utilities. Private lines could include gas, water, sewer, irrigation, phone, and internet, among others.
“When you’re on that site planning the project, take a look around,” says Monica Rakoczy, Owner of EnterTRAINING Solutions. “Look for things like transformers and gas meters that might belong to the property owner. This can be relatively simple if it’s someone’s home, but could be pretty complex if it’s something like a university campus. In those more complex scenarios, we recommend working with a third-party locating company.”
Once you’re comfortable that all of the existing utilities have been located, it’s also best practice to expose those utilities as best you can. Even though some of today’s top locating systems can get to within centimeter accuracy, physically putting eyes on a line is a step worth taking.
“That’s the only way of knowing exactly where those lines are lying and how deep they are,” says Jeff Davis, HDD Product Manager at Ditch Witch. “If possible, you can hand-dig with a shovel. You could also use a vacuum excavation system.”
Pre-dig planning
As important as locating is, there is a lot more to safe digging on a jobsite. As Rakoczy points out, numerous OSHA regulations center on keeping workers safe during any excavation process. That requires an understanding of certain project and jobsite characteristics. A big one is how deep you plan to dig.
Anything deeper than a few feet will likely require some additional excavation measures to protect against cave-ins, i.e. sloping and benching, shoring, or shielding. Certain situations may also require a site-specific system that’s engineered by a professional.
“That will usually kick in around 20 feet in depth, as well as when working near highways and railroads where extra stress is being placed on the ground surrounding the dig,” Rakoczy explains. “Heavy equipment on the jobsite could also necessitate an engineered excavation protection system. These are all things a contractor needs to determine during the pre-project planning phase so they can identify the safety equipment needed to withstand those pressures.”
Ground contamination is another consideration. Warning signs include soil erosion, dead patches of grass, lack of plants and wildlife, and foul odors emanating from the earth.
“Up here in the Northeast, for example, we were an industrial hub many years ago,” Rakoczy says. “When you start digging, there is the potential of finding things like benzene, and even old storage tanks with hazardous chemicals that were buried underground many years ago. It’s important to determine that the ground you’ll be working on is safe for employees to be around.”
Contractors can check with state, county, and local officials to see if there have ever been any environmental concerns with a property. They can also do an address search on an EPA web page, as well as find links to other databases.
As the time draws closer to firing up some excavation equipment and getting to work, contractors must turn their attention to establishing an overall safe jobsite.
“Every state has different rules and regulations on how to properly secure a jobsite,” Rakoczy says about things like signs, flags, stakes, barriers, etc. “So just like with 811, it’s important to understand what the rules are for the specific jobsite you’ll be on.”
Equipment advice
A variety of excavation equipment can be used for underground utility work, from mini-excavators and backhoes to more utility-specific machines like trenchers and HDDs. Regardless of what’s being used, Rakoczy says it’s important to not only have a thorough understanding of how to operate it safely, but also what its limitations are.
“Things like soft ground conditions can compromise safety when using certain pieces of equipment,” Rakoczy points out. “It’s important to understand your surroundings at all times.”
There are also some unique safety considerations with each equipment type.
Horizontal Directional Drills (HDD)
One of the inherent risks with an HDD machine is that it works underground where you can’t see it. Modern equipment with the latest guidance technologies and safety mechanisms gives contractors an edge, such as ESID (electrical strike identification device) which essentially alerts and grounds an operator when a strike is detected.
HDD safety is equally important when the drill has reemerged from underground. Drill lockout mechanisms perform a critical safety task and should always be tested before starting work.
“When a drill enters an entry or exit pit and workers need to get around the drill, lockout/tagout features are integrated into the drill to stop thrust or rotation,” says Braxton Smith, Product Manager at Subsite Electronics. “Then workers don’t have to worry about getting wrapped up in that pipe downhole when they’re changing a reamer or hooking on that product to the back of a tooling.”
The inadvertent return of drilling fluid (mud) to the surface can be another safety issue with HDDs. “If working in the right location, you could end up flooding an intersection, obstructing storm drains, or just making a real mess of somebody’s yard,” Davis points out. Inadvertent returns can be caused by excessive downhole pressure, which can be exacerbated by varying ground conditions, obstructions, and even poor drilling fluid. Contractors must vigilantly monitor drilling operations at all times to minimize the risk of this happening.
Trenchers
Safe trencher operation starts with understanding the work you’ll be asking the trencher to do. Collaborating with your expert local dealer can ensure that you’re setting yourself up to be as safe and productive as possible.
“Soft materials like sand may not be solid enough to hold, while hard-packed soil might necessitate a trencher with more horsepower,” says Brant Kukuk, Compact Equipment Product Manager at Ditch Witch. “Contractors trenching on embankments or in ditches also need to understand the grade they will encounter and the correct direction to trench those slopes. A thorough understanding of the environment and surroundings is a fundamental starting point.”
Once the proper equipment has been selected, operators should diligently study the safety precautions as outlined in the operator’s manual.
“The manual provides detailed safety instructions that are pivotal for preventing accidents and ensuring a secure work environment,” says Karly Rupp, Heavy-Duty Tractors Product Manager at Ditch Witch. “For example, if a person approaches within 6 feet of an operating trencher, the operator must immediately stop the digging chain. This type of guidance helps mitigate risks and protect both the operator and bystanders.”
Vacuum Excavators
This piece of equipment in and of itself is designed to improve excavation safety. By using high-pressure water or air to “soft dig”, a vacuum excavator helps utility contractors work precisely and efficiently while reducing the risk of damaging existing utilities.
There are five common uses in the utility industry, according to Chris Thompson, Vacuum Excavation Product Manager at Ditch Witch:
- Excavating around sensitive areas
- Potholing (daylighting)
- Drill support (i.e. help an HDD get its initial bore going)
- Slot trenching to locate unlocatable utility lines
- Soft-digging holes for utility poles
Whatever the use, Thompson says the unique functionality of a vacuum excavator creates certain risks that the operator and their fellow crew members must be aware of.
“As you step up in classification, some of these larger machines produce up to 5,000 cfm, if not more,” Thompson points out. “You need to stay clear of the dig tube and the dig area. And don’t wear loose-fitting clothing around these powerful vac systems.”
In conclusion
Circling back to where everything started, utility locating, it’s wise for contractors to make sure they are taking advantage of the latest tools and technologies. That includes utility locators with centimeter-level accuracy, as well as mapping capabilities.
“Then at the end of a job, the customer will have a map of the new utilities that were installed, along with the utilities that were already there that the contractor avoided,” Cabello relates. “That’s useful information to have going forward.”
With more and more utilities being put into the ground, the more information you have, the better — especially when that information is as precise and complete as it can get.
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