When we think of preventing third-party damage we immediately think of calling 811, digging safely, locating accurately and keeping accurate up-to-date records and maps. While all of these are very important, preventing third-party damage must begin from the time we install our utilities in the ground.
At a time when preventing and reducing third-party damages is a main challenge for all utility companies, many are utilizing underground space for their distribution systems. Common (shared) trench installations are on the rise and we must do our part to ensure that we have taken every possible precaution to protect the safety of our employees and of the public.
How can we achieve this? It all begins with “proper installation methods.” Taking the time to ensure proper separation of utilities in a common trench and keeping proper separation of the tracer wire when installing polyethylene piping is definitely a great place to start.
Innovative Trench Solutions, Inc. of Rochester, NY has developed several cost-effective, products to help the utility industry achieve safer and more uniform underground installations while maintaining compliance with the revisions to 49 CFR Part 192.321. Included in this revision to the Code is the following regulation addressing the installation of plastic pipe mains and service lines:
Sec. 192.321 Installation of plastic pipe.
(e) Plastic pipe that is not encased must have an electrically conducting wire or other means of locating the pipe while it is underground. Tracer wire may not be wrapped around the pipe and contact with the pipe must be minimized.
The TracerSpacer. The Tracer Spacer was invented by two employees of NYSEG who eventually formed Innovative Trench Solutions, Inc. The device is designed to provide a consistent separation between polyethylene piping and tracer wire in natural gas installations. Proper spacing between the plastic gas pipe and the tracer wire has long been an industry safety concern. If there is no separation between the pipe and the tracer wire and the wire should become accidentally energized by a lightning strike or by any other stray voltage it will melt through the polyethylene gas pipe causing a dangerous leak. This could result in the loss of life or property, not to mention the very costly task of repairing or replacing the gas main or service.
The TracerSpacer is actually a dual-purpose product. It ensures the tracer wire remain a safe distance from the gas pipe as to not allow contact, yet it holds it close enough to increase the accuracy of your underground locates. This is a great benefit in the prevention of third-party damages by reducing your company/contractor mis-marks.
One Texas utility states “By using the TracerSpacer we will always be in compliance with our O&M procedures no matter if the job is done by a contractor or our company employees. The use has been met with great approval by state regulators.”
Having peace of mind that — when the construction crews backfill — the tracer wire will not be displaced to the opposite side of the trench, will easily allow you to record on your as-built maps that the tracer wire is four inches to the house side or four inches to the road side of the gas pipe being installed. This can only be a positive tool to help improve the accuracy for the many people who locate underground facilities each day.
The TracerSpacer seeks to be a guarantee that you will be well within the tolerance permitted by your state’s one call system when marking out your underground facilities.
By installing the tracer wire parallel to the pipe (as opposed to above) you are ensuring an accurate depth location of your pipe, and eliminating the possibility of an accidental third-party break in the tracer wire which could go unreported to you. This will cause locating problems for you in the future for sure. An accurate depth location cannot be achieved if your tracer wire is installed above or below the pipe. The Tracer Spacer eliminates the time consuming chore of padding the wire, then padding the pipe, and therefore increasing jobsite productivity.
Common Trench Separation Compliance. In 1999 a gas explosion in Virginia involving arcing electric lines near gas lines was determined to be the cause of a fatality. The National Transportation Safety Board (NTSB) investigation concluded, “Had the gas and electrical service lines involved in this accident been adequately separated, the heat from the arcing electrical failure would probably not have damaged the gas service line, and the accident would not have occurred.”
The report went on to say, “The presence of corrosion and subsequent overheating and arcing at a splice in one of the conductors of the nearby triplex electrical service ignited an overlapped gas line causing the explosion which resulted in the fatality”.
After the Virginia fatality, a Common Ground Alliance (CGA), subcommittee was asked by the NTSB, to write a separation best practice. It took the subcommittee 18 months to gain industry-wide consensus on the separation guideline. In September 2003 the CGA Board of Directors approved for inclusion in the CGA Best Practices Manual the following best practice for separation:
“When installing new direct buried supply facilities in a common trench, a minimum of 12-inch radial separation should be maintained between supply facilities such as steam lines, plastic gas lines, other fuel lines, and direct buried electrical supply lines. If 12 inches of separation cannot be feasibly attained at the time of installation, then mitigating measures should be taken to protect lines against damage that might result from proximity to other structures. Examples may include the use of insulators, casing, shields or spacers. If there is a conflict among any of the applicable regulations or standards regarding minimum separation, the most stringent should be applied.”
Al Yonkman, Detroit Edison, who was representing the electric utility industry on the CGA Board of Directors says, “It was a highly debated issue, because of the impacts on all utility installation procedures, but, it will establish a safer standard for installation of utilities, save lives and help to prevent utility damages in the future.”
The TracerSpacer for Common Trench. Like the original TracerSpacer this spacer also holds the tracer wire in close proximity to the gas pipe while ensuring that the other utilities in a common trench maintain a safe distance and do not become displaced during backfill.
For the safety of the public, we must ensure that our polyethylene gas pipe does not make contact or even come into close proximity to any underground electric in a common trench installation.
The snap-on design of this spacer will greatly increase jobsite productivity in comparison to present methods used by the industry. Tracer Spacers for common trench applications can be used in wet trenches and can even be used in rock or shale installations.
The TracerSpacer and the TracerSpacer for Common Trench are two very simple ways we can help to organize our underground utilities and keep the public and ourselves safe from potentially tragic and unnecessary situations.
The method in which we choose to install our underground facilities today will determine the integrity of our systems for years to come.