Volume 27 • No 04 • 2004
ISSN 0742-468X • Since 1978
On-line Since 2000
Using Parcels
for
Pipeline Integrity
Pipeline integrity, and with it High Consequence Area analysis, is keeping the systems integrators busy these days. Nobody in the pipeline (gas or liquid) industry ever wants to experience a pipeline explosion or similar accident. Now with the US government watching, companies must make sure they are complying with the rules
The detailed requirements are what you might expect of a federal regulation. Rather than repeating them here, you can familiarize yourselves with the details, starting at http://www.epa.gov/fedrgstr/EPA-IMPACT/2002/August/Day-06/i19840.htm.
In summary, the regulations say that you have to know where your pipelines are located and if they are in a dense area, you have to tell the feds all about it. That seems to be the short version of the regulations, probably brought on by the use of the term High Consequence Areas (HCA). However, as one integrator told me, the regulations are about developing an internal management plan for ranking field inspections by priority
How do parcel maps help?
In complying with the regulations, the pipeline company has to know where its pipes are located. That means it needs the facility maps to show location to a meter, which structures are in the same corridor, and the proximity of the pipeline to the structures. other maps such as soil subsidence and fault maps are useful to determine likelihood of problems.
Opinions differ about the usefulness of parcel maps. Some system integrators don't see the need for it, since the regulations don't specify parcel maps. GIS managers in pipeline companies often immediately see the benefit of understanding the true location of a pipe in relation to a property line and to be able to access situs information about a parcel. The parcel boundaries add detail to any photography that may be used. However, for pipeline transmission companies, the use of parcel boundaries may not add very much to the analysis. These pipes tend to be in open areas with few or no structures. Based on the formulas in the regulations, in low density areas buffer zones can reach about 1,000 feet from the pipe. So, if there are few or no parcels in 1,000 ft of the pipeline, the accuracy of parcel maps is less important.
Who uses parcel maps?
Gas distribution companies, on the other hand, will find a big advantage to the accuracy of parcel maps. In the denser urban areas where the pipeline can be as small as two to six inches, the HCA calculations bring the buffer to fewer than 50 ft. At that point, locating a building as accurately as possible substantially adds to the analysis./P>
A large California combined power utility used parcel maps to provide and maintain a seamless database of over five million parcels covering their service area. This approach is helping the company to ensure the integrity of its gas distribution pipelines. The parcel data and local data release agreements were provided by Boundary Solutions Inc. (www.boundarysolutions.com).
As part of identifying high consequence areas, a calculated buffer, based on density determines the pipeline's proximity to occupied areas. Parcel maps show the points in a parcel's boundary within 6 feet of their true location, instead of a single point often not located within the parcel. Compared to the use of a buffered lat/long address point derived from the United States Postal Service (Zip code) database, digital parcels map databases are far more accurate.
The reason address points often are not within the subject parcel is because of address-range anomalies; worse, they can be hundreds of feet away. The improved accuracy of parcel maps goes a long way to reduce incidents of erroneous reporting. Another benefit is that when the updates to the parcel maps are loaded (often quarterly) density changes can be spotted quickly.
As a side benefit, by bringing the parcels into the utility's database, other user groups gain tremendous spatial advantages. Groups such as right-of-way, marketing, field services and others all benefit from knowing the true intersection or juxtaposition of the pipeline and the parcel boundary.
Conclusion
The government regulators may not specify parcel maps, but parcel boundaries add value to pipeline integrity and will benefit other areas of your enterprise. It is your company. Comply with the regulations, but make the analysis and underlying data useful to the entire company.
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