Trenchless pipelining is becoming increasingly popular, and so are the pipeline hazards that workers encounter. This method of replacing old, damaged pipes is much less disruptive above ground than traditional pipe replacement is. It also saves time and money in comparison with conventional pipe replacement methods. But it requires skilled workers who know what to look for, even when they can’t see what’s underground.
The biggest concern is during horizontal directional drilling (HDD). Locating the existing services underground is often challenging, especially when there are non-metal pipes and cables involved. Sometimes they aren’t marked and the depths of the utilities aren’t known. If the installation crew doesn’t see the pipe that’s already there, this method poses pipeline hazards that could cost more time and money to fix. Cross bore incidents, in particular, are becoming a growing hazard as more utilities turn to underground installations.
What Is a Cross Bore?
A cross bore is an intersection where utilities like electrical lines, gas lines, telephone, or television cables cross. As more companies turn to underground real estate, there’s more to run into during HDD. The various types of lines that can create a cross bore pose some very real hazards.
Cross bores occur when any new utility line is installed underground and makes contact with an existing one. Many companies use trenchless methods similar to that of trenchless pipelining. Any time one company intersects another line, there is a risk of creating a hazardous situation. For one, rupturing a natural gas line could all gas to enter the sewage line and cause an explosion. The person doing the digging is also at risk. If they strike an electric line, they could be seriously injured or killed.
Preventing Pipeline Hazards
The first word of advice for any working plan to dig is to get a ticket from DigAlert before you start. The organization informs you of all members who have underground facilities in the area. But, it’s not a perfect recording system so you still need to be cautious. The problem with DigAlert records is that sometimes the people installing these lines run into trouble and end up inadvertently creating more problems. When they decide to go around an obstacle instead of moving it, the lines end up running in a different place than recorded. Sometimes records aren’t submitted in a timely manner. Not including an accurate depth is another issue with the records. Still, failing to call DigAlert before you dig can result in serious fines and repair costs.
Another problem is that sewer and stormwater lines are often made of non-metal materials and they aren’t marked. Cross bores sometimes exist for years without detection. During this time, tree roots may grow into the pipe and camouflage the cross bore so that it isn’t detectable. At the same time, roots are a common cause of damaged sewer lines, leading to the need for pipe replacement. When the homeowner calls a plumber to repair a backed-up sewer line, they insert a sewer camera into the line. All they see is blockage caused by the root growth. They proceed to cut away the roots with a root cutter, sever the gas line, and gas feeds back into the home. In this case, there is a high risk of causing an explosion, structural deficiencies to the sewer system, sinkholes, and voids within the ground. Some of these pipelining hazards can cause serious injuries or death. All of them lead to higher costs and extensive repairs.
Preventing Cross Bore Strikes
Implementing some simple, cost-effective steps can prevent the risk of cross bores, including:
1. Tracer Wire System
The key to preventing a cross bore is in identifying the location of lines that are already in place. Tracer wire, (also called locator wire or locating wire) helps find pipes after they are buried. The use of a tracer wire helps prevent problems in the future. Both the choice of the wire system and the proper use ensure the tracer wire is effective.
As the use of HDD has continued, a number of types of tracer wire have become available. When using the application for the installation of sewer pipes, it most often involves non-metallic pipes made from polyethylene and PVC. Often, the pipes are also joint restraint and fusible, meaning there are no metal components throughout. These pipes don’t offer a source for a locator to send a signal. That means a metallic component must be added during the process. That’s where the tracer wire comes in.
Once the pipe is in place, workers place the wire along its length before buying it. Later on, when a utility company adds another system, the wire provides a ‘trace’ to locate the pipe. The wire tracer is an above ground device that works without electricity to trace the wire. The wire system provides information on the location of non-metal pipes, including their depth. Once installed, the wire system connectors last the lifetime of the pipeline.
Sometimes a tracer wire isn’t used or the installation isn’t complete. To reduce the future risk of pipeline hazards, the choice in the size and type of tracer wire used is important. HDD projects tend to require the strongest wire, particularly when pipe bursting is used. Harsh conditions such as hard soil and rock make it more difficult to pull the wire through and make the proper connections. Making the right choice in wire and performing the process correctly can have a big impact on the future safety of HDD projects.
2. Working on Assumptions
Plumbers should assume there’s a cross bore instead of assuming there isn’t. Pipeline hazards are real, and cross bores occur frequently. Explosions, injuries, and deaths have occurred. Too often, the risk isn’t discovered until a sewer line gets clogged and the homeowner calls a plumber to unblock it.
3. Using a Sewer Camera with Sonde
Sondes are transmitters that pipeliners sometimes use in combination with pipe locators. The transmitters use radio frequency that provides the horizontal position and the approximate depth of a pipe. All cameras don’t operate with the same level of sophistication. They vary from simple ‘push rod’ cameras that must be pushed through the opening leading into the pipe to those using the latest technology, which are launched through sewer manholes to inspect main sewer lines. Once detected, the workers mark the locations on the surface using paint, providing easy access. The information provided minimizes the risk of creating a cross bore.
4. Resorting to Conventional Pipe Replacement
If the plumber is unable to confirm the location of existing utilities, the homeowner may have to resort to conventional pipe replacement. Trenchless pipelining isn’t recommended in some situations. If that’s the case, vacuum excavation equipment or traditional excavation with hand digging works the best. In the event that the excavators find a cross bore, they should provide an immediate repair.
Safety and Awareness: Still Under Review
How big of an issue are cross bores? So much so that there is an organization dedicated specifically to reducing the risk cross bores pose to people and property. The Cross Bore Safety Association (CBSA) is an organization founded by a group of industrial professionals to reduce the dangers associated with cross bores. One issue that most experts agree on is that we need to increase awareness of the potential dangers of HDD.
Advanced technology is available, at a cost that most contractors and utility companies can afford. Maybe if utility customers learn more about the serious threat involved, they can start asking a different set of questions when hiring someone to put in new pipes or lines.
They should also realize the frequency and seriousness of pipeline hazards that can occur when natural gas lines and sewer lines intersect. It couldn’t be more important for plumbing companies to follow acceptable installation practices. Those that cut corners to save on costs or time put themselves and the occupants of the home at risk.
Some of the steps available to plumbing companies today help reduce the potential risks, but they are far from perfect. For example, the way the operator holds the receiver affects the results produced by sonde. The accuracy is also impacted by debris, settlement, and offset joints. Lateral pipes, which are very common in the San Diego area, can affect accuracy by as much as 8” from the sonde position.
Choosing the Best Trenchless Sewer Repair Company
When your sewer starts backing up, you need to get a plumber who responds quickly. Make sure you also get a company with in-depth knowledge about trenchless sewer repair. They will offer you the most effective trenchless method for your needs at the lowest possible cost.
Most importantly, a company with years of experience and the most advanced technology will reduce the risk of pipeline hazards associated with cross bores. Any effort at all reduces the danger to some degree. But the most advanced methods of detecting location offer the greatest reliability. Check out a company’s reviews, accolades, and awards. Nothing speaks more to their capabilities than the quality of service they’ve provided time and time again.
If you are considering a trenchless repair, contact San Diego Pipelining. We use the most advanced technology to bring you the best, safest pipe lining services. We have the best customer service in the business.