GPS/GIS automates mobile gas leak detection
The Pilot
Like any other innovative technology project, the pilot was used to test the concept of integrating the
numerous technologies that were proposed. An existing FIU, an existing GPS receiver with a DGPS
receiver, an existing laptop PC 486-25, an AC/DC power converter, an existing LD vehicle, and a new
piece of prototype technology called an Optical Methane Detector (OMD) was used in the pilot. The
original pilot concept did not call for the use of the OMD, but the opportunity was there, and it was used.
As detailed in the list of equipment, problems are already occurring. To have the FIU talk to the PC, an
analog to digital interface needed to be established; however, there was not an 1/0 port on the FIU to talk
to the PC. A port needed to be added to the FIU, tested, and software written to read the output by the PC
and to put the data in an understandable format. The OMD also needed a communications link to the PC;
although, this was easily established through the use of an existing RS422 communications port on the
OMD. Again, the software needed to read the output from the OMD and the FIU. The PC being used did
not have a cigarette lighter device available for power, so an AC/DC power converter was installed to
power the PC and GPS receiver. Depending on how the converter was wired, a ground loop would occur
and stop communications between both leak detection devices. Two final pieces were left to contend
with—the GPS receiver and the DGPS receiver. The installation portion was adequate, but a few months
into the pilot, the DGPS signal was disabled by MnDOT. So the 1-meter, real-time accuracy that was
being achieved early in the pilot was gone. There are other DGPS alternatives, such as Accupoint and
Omnistar; however, neither of which were used for the remainder of the pilot. The GPS portion of the
pilot in general worked very well until the leaves on the trees appeared. The urban areas became a
problem with the tree canopy blocking the GPS satellite signal, which in turn stopped the recording of
data until satellite lock was regained. A data communications link was not used for the pilot, so data was
transferred using diskettes. This was suitable for a one-vehicle pilot; for five vehicles, the diskette
transfer was not an option.
A pilot typically is used to prove concepts, to find weaknesses in the system, and to gather user input on
the concept and the workings of the system. Although there were problems with the equipment and
software integration and some GPS issues, the system performed well overall for a minimal amount of
work and dollars. One of the major issues that was perceived during the pilot was that the technicians and
the LD manager saw the pilot as a leak detection pilot and not as a data collection GIS integration pilot.
Now that they are looking at the project differently, many new thoughts are arising regarding the use of
the newly found data, including how the issues of the backpack leak detection crews were going to be
addressed. The technology at the time of the pilot was not at a point where the backpack issues could be
addressed at a reasonable cost.
The Benefits
The pilot project cost-benefit had been originally based solely on the fact that there would be a
tremendous time savings on the part of the LD technicians and the LD clerk. Approximately one-third of
the daily time would be saved due to the automation of mapping and electronic transfer of data to and
from the LD vehicles. There would be no more hand coloring of maps and no more, or minimal, data
entry by the LD clerk. Electronic Leak Sheets would be field originated, and the ability to dispatch repair
crews in a more timely fashion with more accurate location description information would be seen as
benefits.
Using the power of GIS, the data collected during the LD surveys can now be easily analyzed.
Forecasting of leaks can take place and differential calculations from previous data to current leak data
can be made to help identifi the frequencies at which leak surveys could be done. Accurate time
estimations for the routes can be established, and if the traffic flow information is in the GIS, better and
more efficient routes can be established. Routes can be established on cyclical information as opposed to
geographic areas. Through the better routing process not only can the time of the LD technician be put to
better use, but there can be a large savings on vehicle maintenance, gasoline, and overall operating costs
of the vehicles. This paragraph address issues that are somewhat intangible at this point, but you can see
that with a little foresight, field data collection projects such as this will have a tremendous impact and
benefit to the utility industry and help them establish themselves as world class organizations.
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