Jordan Hollingsworth, CSP, CRIS, CHST, CHSP
Safety Advisor
Nothing brings construction projects to a halt faster than the discovery of a gas pipe, electrical line, sewer tile, or water pipe that nobody knew was there. A crew with a backhoe is digging a trench and makes an unfortunate discovery. If they’re lucky, they recognize the line before any damage is done, or they quickly determine that it’s a short segment of a long-abandoned leg. If they’re not so lucky, they may get to see themselves on the news that evening.
Despite the best efforts of utility companies, marking contractors, state regulators, and contractors, surprises often await just a few feet below the surface. Even when discovering those surprises doesn’t result in injury, damage, or a loss of power to an entire community, it can create a significant delay for the project as the crew attempts to identify the line and determine the best way to work around it.
These days, most utilities and property owners do a great job of recording what they put under the ground. Unfortunately, that hasn’t always been the case. Gas pipes, sewers, and water lines from the early days of those technologies were installed with little thought given to the possibility that someone might encounter them decades down the road. Utility lines used many years ago may have been bypassed by bigger lines with more capacity, but nobody thought to go back and remove the old ones. And anyone who has ever been involved in the renovation of an old building knows that every day seems to bring the discovery of something that wasn’t in the drawings.
Fortunately, there are steps you can take to minimize the risk of unexpectedly encountering underground utilities. It takes extra planning in the early stages of the project and a little bit of additional investment, but that’s a small price to pay when you consider the schedule disruptions such discoveries create — or the cost of repairing the damage your project created to a major utility line.
PLANNING IS JOB ONE
Workplace safety strategies always begin with a plan, and that’s for good reason. When you stop and take time to plan, you have the opportunity to think about all aspects of a project. You can consider the potential hazards and create strategies to avoid them, or build contingencies into your plan.
Start by trying to obtain all of the drawings that may have been created for the area in which your project is located. That includes the plans for any previous structures, the utilities’ own blueprints, drawings for past installations or renovations — anything that may give you a clue into what lurks below the surface. Compare the drawings to identify inconsistencies. If one drawing shows a gas main in one area of the site, but it’s not duplicated in another, it may have been missed. If you’re not sure it’s there, assume it is until your crews prove otherwise.
If your state or area requires a call to a public utilities locate service, make that call early in the process. That’s a big help, but in my experience, it isn’t enough. After the public locate service has finished its work, I encourage owners and contractors to bring in a private locate service for a closer study of the area. In addition to performing a more thorough inspection, private locate services will generally create a map of everything they find, which you can then compare to the drawings you have. Yes, working with a private locate service adds a cost to the process, but if they discover even one power or gas line that the public locate crews missed, you’ll save a significant amount of money and time in the long run. I look at it as insurance.
DAILY COORDINATION
As the project moves along, include underground utilities in your daily coordination meetings with the excavation contractor. Review the drawings with them, and discuss their strategy for working around the underground sites that have been identified. Develop a hazard analysis for each task that will be performed, and identify measures to protect workers.
One general contractor I worked with in the past required their excavating contractors to follow a very prudent practice. They would begin by daylighting every utility in the area where they would be working, Then they’d place a piece of PVC pipe up against the line and backfill it. That way, at any time during their work, their crews knew the exact location of the lines and could drop a measuring stick down the PVC pipe to get an exact depth.
Make sure that the contractor keeps good records of daily activities, including a log of dig numbers. That’s important, because if a problem with an underground utility line crops up, one of the first things investigators will ask for is the dig number.
Set limits for how closely excavating equipment can work from the marked line locations, and be sure to keep those markings visible throughout the project. Once underground utility lines have been exposed, take steps to ensure that workers know where they are to protect the lines from damage. If you need to trench around the lines, use trench shields to protect the walls of the trenched areas.
USING HYDRO EXCAVATIONS
Another best practice for working around underground utilities is the use of hydro excavating equipment. Hydro excavating combines the use of high-pressure water with a vacuum truck to remove soils around utility lines with minimal damage to the lines themselves.
There’s a misconception that hydro excavating is more costly than the traditional approach of digging by hand, but contractors who favor the hydro excavating approach will be quick to tell you that it’s more cost-effective. If that seems counterintuitive, consider that hand-digging is a slow, labor-intensive process that also creates a greater hazard for workers and an increased likelihood that an underground utility line may be damaged. By choosing hydro excavating, contractors save a significant amount of time and reduce the risk of injury and damage.
RESPONDING TO SURPRISES
No matter how thoroughly you prepare, someone will inevitably discover an underground utility that wasn’t marked and that didn’t appear on the drawings. Ideally, they’ll spot it before they manage to cut into it.
Stop work immediately and bring in the supervisor or owner’s representative who has access to the drawings for the site. If you can identify the specific type of line, call the appropriate utility company, too. If you can’t tell what it is, bring in representatives from all of the possibilities, because your first step is to know what you’re dealing with.
Once the type of line has been identified, you need to determine its path. Dig again three feet away to see if you encounter it. If so, continue the process until you’re able to mark its entire path. If not, you may have happened on a short segment that was abandoned or left over from a previous project. In that case, try to find both ends so you can determine whether you can safely remove the line. If so, work with the excavating contractor to develop a safe plan for removal.
Of course, if the line is broken, you should take steps to protect all workers in the immediate area and follow the emergency action plan. If the line that is broken is a natural gas line or is otherwise flammable, everyone should evacuate to a safe distance.
CREATING A NEW RECORD
As you proceed through the project, use the information you’ve found from past drawings, the locate services, and any additional lines the crews uncover to develop updated drawings for the project owner. Private locate companies may include updated drawings as part of the services they provide. While the owner may not require those drawings as part of the contract, they are an extremely valuable resource for future work, and provide an added value that will always be appreciated.
