August 2018, Vol. 245, No. 8

PPSA 2018 Pigging Update

Accessible Pipeline Data Becomes Focal Point of Safety

By Erik Dahlberg

Many of the world’s most vulnerable pipelines are in developed and municipal areas, where it can be difficult to locate miles of gas pipelines in these regions. And where locations exist, the data may not be in an easily retrievable and shareable format. 

By not having accurate, readily available location data, pipeline operators, construction companies, farmers, landowners and other stakeholders face the risk of accidental and potentially catastrophic damage to a buried gas pipeline.

The U.S. 2016 Protecting our Infrastructure of Pipelines and Enhancing Safety (PIPES) Act requires increased use of data and technology to improve pipeline safety. The legislation is vehemently supported by industry players and calls for ways to prevent damage by third-parties, such as inadvertent contact with a buried line.

Woolpert surveyors sometimes use a SPAR 300 subsurface utility locating system in conjunction with survey-grade GNSS to track and geo-reference underground utility lines. A client’s property in northern Ohio was one of their first projects.

“We used the SPAR unit coupled with Trimble R10 GNSS receivers to detect buried gas lines,” said Dave Kuxhausen, Woolpert discipline leader for surveying and geomatics. “The scale of the project was sufficient to demonstrate that we had the capabilities to perform this type of work.”

Magnetic field sensors determine the distance to a buried pipe or other asset capable of carrying an electric current. The sensors can be integrated with receivers or total stations connected to software.

The system locates buried pipes in three dimensions. The controller indicates when the SPAR has located a pipe and aids the crew in following the pipe. The system provides horizontal and vertical offsets from the sensor to the pipe while the GNSS receiver supplies precise geographic positioning.

To capture a measurement, the field software automatically combines the data from the SPAR and GNSS sensors and stores the resulting positions into its database. In addition to a 3-D coordinate on the pipeline itself, the solution also produces coordinates for points on the surface directly above the pipe.

Surveyors can detect and mark the pipe as well as capture survey-grade positions in a single pass. The resulting locations approach the accuracy of Level A excavations. (Level A locations require the pipe to be physically exposed, usually by digging or hydro-excavation.) Kuxhausen said that the system enables his crews to capture pipe depths accurate to roughly 8cm, depending on the integrity of the tracer wire. Crews can work with the speed and flexibility associated with handheld electromagnetic sensors not capable of determining a pipe’s depth.

The SPAR systems easily stay in use. Kuxhausen said his clients recognize the value of the mapping solution. Beyond the mapping required by the PIPES Act, demand for their mapping services comes from large and small construction companies. The work includes locating utilities for new construction as well as maintenance and update projects.

When working on the projects, there isn’t much flexibility, so the accurate locations are important for efficient design and construction. “In a lot of places clients are forced to do Level A excavation just to locate a pipe,” Kuxhausen said. “They may need data every 10 feet along the road. We are able to use this system to reduce the frequency of the Level A excavations to say, every 50 feet. It’s a faster and more cost-efficient approach.”P&GJ


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