Avoiding existing underground utilities is becoming a challenge for many cities and municipalities. Adding to the challenge is incomplete or spotty data on a continuous pipe. For example, a city may have as-built information that is accurate. However, because tracer-wire or metallic tape has deteriorated or is missing, there’s no solid way to independently verify the accuracy of the information 30 years later. This can lead to questionable and inaccurate field data.
This is the case for the public utilities division within the City of Charlottesville, Va. The city maintains and operates its own natural gas distribution system, as well as all of the water and sewer lines. While the city knows the location of the gas distribution lines, these lines have never been fully mapped and trying to plot the lines geographically has been a challenge. Thus, knowing the exact location of the gas distribution lines dating back to the 1970s when metallic tape was used is not an easy job.
To help overcome this challenge, the City of Charlottesville is undertaking a multi-year project to map the gas distribution lines using GPS-enabled underground utility locators. The project is part of a larger effort being coordinated by the Virginia Utility Protection Service Inc. (VUPS) located in Roanoke, Va., to enhance two-way communication and data sharing between underground utility stakeholders. VUPS is a one-call notification center for the state of Virginia that notifies utilities of upcoming excavation work so they can locate and mark the underground facilities in advance to prevent possible damage to underground utility lines — in turn, preventing injury, property damage and service outages.
“We’ve developed a program to expand our basic services beyond just mapping, determining the area of excavation and distributing notifications,” says Rick Pevarski, president and CEO of VUPS. “The new program will reduce the number of over-notifications, provide enhanced data to excavator and facility owners and ultimately provide two-way, real-time communication between the one-call center and the excavator at the jobsite.”
The project began in 2007 and involves the integration and application of GPS technology to locating instruments and the development of electronic manifests tracking the locator’s activity. Specifically, utility markings will be overlaid onto the ortho-photographic maps to provide a bird’s-eye view of the excavation site. This enhancement will improve the detail currently seen in manually created manifest records.
“Utility operators can use the data as a verification of their own maps and records,” says Pevarski. “The excavator can view an image that provides a birds-eye view of what was located with a much clearer picture of where those lines run from a big-picture perspective.”
Pevarski says that many times excavators arrive at a site and see paint and flags all over, making it difficult to decipher. But when they can see an aerial or bird’s-eye view, it becomes much clearer. This data is shared with the utility, allowing them to verify their own maps and records.
Leading the effort for the City of Charlottesville is Mary Zylowski, an engineering technician within the public utilities division responsible for maintaining all the gas facilities maps. Most of her work involves gathering line location data for existing and new infrastructure.
“In many cases our gas distribution lines have been plotted, but in some cases the paperwork doesn’t exist for some of the older lines,” says Zylowski. “This really limits our ability to efficiently locate lines in the field and we have difficulty validating the information.”
Zylowski also believes eventually a mandate will be in place requiring a locator’s manifest to include a time and date stamp indicating the locator was actually onsite at a particular day and time completed the utility marking. GPS-enabled locators will help the industry to create manifests with digital date and time stamps corresponding to each dot on the map. This will verify that her team of locators completed the job and help her determine if certain areas need more data collection.
“If we don’t have any existing paperwork in the office for that site, our locating team will collect more points,” says Zylowski. “Ultimately, the city will have better data as to the location of these underground lines.”
VUPS invited leading utility locator manufacturers to participate in the project. Specifically, McLaughlin developed software applications that allowed its Verifier G2 utility locator to share real-time data with an integrated Magellan GPS unit installed onto the unit.
Two software applications are loaded into the locating receiver. These programs allow the receiver, through a serial port, to export real-time depth, current measurement index (CMI), frequency and locator mode to the integrated GPS unit. A second software program allows the Windows-based GPS units to receive the locator data. When the GPS unit receives that data, it cues the Magellan unit to record the latitude and longitude coordinates for the specific underground facility.
“The entire process is done automatically,” says Matt Manning, locating equipment product manager for McLaughlin. “Magellan GPS units are mounted to the utility locator and it’s a one-hand operation. In other words, once you’ve got the GPS unit set up, you basically are controlling all the locating and GPS recording with the push of one button on the utility receiver.”
The process is quite simple. A locate request generates a ticket for a specific address or location. The location may have anywhere from one to multiple lines to be identified. Then the city’s utility locator arrives and locates the underground facilities on that ticket, sending the data in real time and capturing the latitude and longitude for mapping capabilities.
“Other applications coupling the GPS unit to a locator existed, but they worked independent of each other,” says Pevarski. “What we’ve accomplished is an application that completely integrates and couples the GPS unit directly to the locator. The McLaughlin applications allow the locator operator to push the depth button and in one step collect the depth, longitude and latitude location of that utility.”
A number of facility owners have already mapped, through GPS, their surface features and attributes like transformers. Now facility owners have a simple software application that will allow them to easily map their underground facilities. The facility owner can download the raw data into a geographic information system (GIS) and use it to update or create their internal maps and overlay the information onto aerial photos, along with the other surface facilities that they’ve mapped.
The City of Charlottesville employs two full-time locators and they have been using the GPS-enabled locators since 2009.
“In the future, we want each of the four gas utility crews to carry their own GPS-enabled locator,” says Zylowski. “This way when they are installing or repairing a line we can immediately digitally map the location, helping to reduce our future mapping workload and enhancing our data.”
Zylowski is happy with the system and it shows — they turned in the largest number of tickets among all the entities involved in the VUPS project.
“Obviously we’ve embraced the technology,” says Zylowski. “It’s helping us to map our gas distribution lines and saving us time. It’s a great project and technology.”
Greg Ehm is a technical writer in Des Moines, Iowa.