Investment in research and development of technology for detecting and mapping underground infrastructure is accelerating. The Common Ground Alliance (CGA) has initiated an annual Common Ground Alliance Technology Report. The report not only describes existing and new technology, but also identifies gaps or unexplored areas to encourage new research and development in locating and mapping subsurface utilities. The first report was released that this year's CGA 811 Excavation Safety Conference in Phoenix.
The report also includes case studies of new technologies under development. This year's report included a case study describing the demonstration of a radar look-ahead device for trenchless digging.
Trenchless digging, also called horizontal drilling, is widely used in North America and Europe to install new underground infrastructure including gas and water distribution lines. However, there is a significant risk of hitting existing subsurface infrastructure. For example, cross-bores - where gas lines penetrate sewer pipes - occur frequently when using trenchless drilling to install new gas lines. As I have discussed in a previous blog post, there is a large industry segment focussed on detecting and fixing cross-bores. Penetrating sewer pipes can lead to hazardous complications in the long term, but many cross-bores remain undetected for years. However, hitting other infrastructure such as an electric power cable or gas line can be very dangerous not only to the operator but also to nearby structures and people. Hitting telecommunications cables can lead to many people being without phone or internet service.
The European project ORFEUS has development a horizontal directional drilling machine with “look ahead” technology, which consists of radar incorporated into the drilling head to detect and warn the operator of obstacles during the drilling operation.
Experiments using the technology were conducted in Paris and at Pacific Gas and Electric’s (PGE) training facility in Livermore, California. In the Paris trial 75 meters of polyethylene (PE) water pipe were installed in a conjested area of Paris using the new horizontal “look ahead” drilling. The subsurface was very congested with many buried pipes that were crossing beneath or above the drill head. Pits were excavated to validate the exact position of the existing infrastructure. But many other unknown obstacles were also present, such as old foundation walls, pipes and other buried items. During the drilling operation, the ORFEUS system detected an unknown object not shown on the as-built maps, which potholing revealed to be a previously unknown electrical cable.
In Livermore a successful demonstration of the technology involved a previously prepared area where a selection of non-conductive and metallic pipes with different diameters and layout with respect to the planned drilling path had been laid during the period before the trial. In addition, two boulders were also buried in the area, as well as the installation of a “joint trench” in the final part of the test site.
Funding for further development is being pursued. ORFEUS technology could be commercialized and used by utilities within 2.5 years.
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