Utility Applications for Micro Impulse Radar (MIR) and Underground Imaging Technologies
Source: Lawrence Livermore National Laboratory
Date: 1/1/95    Record No.: 10084
Contact: John Warhus, 510-423-2783

Utility Applications for Micro Impulse Radar (MIR) and Underground Ima...
Lawrence Livermore National Laboratory (LLNL) has developed technologies with the potential to solve some important problems for utility companies. Two problems for which new and emerging technologies have the strongest potential are:

*Non-destructive detection and characterization of rot in wood utility poles
*Locating and mapping underground utilities (pipes, conduits, cables, etc.).

The Problems
The 100 million or more wood utility poles in the U.S. and perhaps 1 billion or more world wide represent a huge investment for utility companies. In addition to existing techniques, which include visual inspection, core boring, and using non-destructive acoustic methods which enable crews to assess residual strength, low-cost tools are needed which can be used to pinpoint and characterize damage resulting from wood pole rot. Such tools can provide more quantitative information on which to base repair and replacement decisions and optimize pole management efforts.

Underground and buried utilities represent another huge investment by utility companies. These facilities must be installed and maintained, and good knowledge of the location of existing facilities is crucial to safe, cost-effective underground operations. Typically, documentation for underground installations is inaccurate or does not exist at all, resulting in the need for underground surveys at sites where operations (construction, troubleshooting, repair, etc.) are conducted. Ground penetrating radar (GPR) is a surveying tool that is often used, with varying degrees of success, for performing these surveys. Unlike many of the other tools used for underground locating and mapping, GPR has the capability to provide not only 2-dimensional surface maps, but also accurate measurement of depth. However, one of the primary limitations of GPR that has restricted its use is that the data it produces are difficult to interpret. Because of this limitation, utility companies often contract for GPR surveying services, at high cost, to companies that specialize in using GPR. Improvements in data interpretation and in overall operational effectiveness could make GPR a much more useful underground utility mapping tool.

Technology Descriptions
Micro-impulse Radar (MIR) is a new radar technology developed at LLNL with the capability to penetrate dielectric materials like wood, concrete, and soil, as well as air, and provide high resolution detection of changes in material dielectric and conductivity properties. In addition, it can be used to accurately measure distances, sense fluid levels, and detect motion in operating environments where other sensor technologies (e.g., acoustic and infrared) fail. MIR operates at very low RF power levels (< 0.5 W peak and << 1 mW average) ensuring operator safety and non-interference with other electronic systems. MIR uses low-cost, off-the-shelf electronic components to produce compact, user-friendly instrumentation. This technology has been licensed for use in low-cost, high-volume electronic hand tool and automotive applications and is available for licensing for other applications. [One company is making a stud-finder!]

LLNL has combined MIR and other related radar technologies with unique imaging software to provide a capability for high resolution imaging of objects embedded in dielectric materials. The imaging software tools were developed in an R&D program directed at developing radar as a tool for inspecting steel-reinforced concrete bridge decks. Systems based on this new approach do not require direct contact of the sensors with the structure to obtain inspection data and, as a result, can collect data over large areas of bridge deck very rapidly. Images reconstructed from the radar inspection data will enable bridge engineers and inspectors to visualize structural details (e.g., location and condition of structural elements, layer thickness, moisture content, etc.) that were previously only observable using destructive techniques like coring. The program succeeded in developing and integrating these technologies and proving their feasibility for the inspection application. Under funding provided by the Federal Highway Administration, LLNL will develop and deliver a prototype bridge deck inspection system based on MIR and underground imaging technologies. That project is scheduled to start in February 1995 and with prototype delivery in mid-FY96.

Application of these LLNL Technologies to the Problems
LLNL is preparing to conduct a small research effort aimed at evaluating the feasibility of MIR and radar imaging technologies for use in detecting and characterizing rotting in wood poles. Used alone, MIR technology offers the potential for a low-cost, hand-held pole rot detector that could be used for routine field inspections to identify suspect poles. Using a more sophisticated instrument which combines MIR with imaging technologies, detailed inspections can be conducted on suspect poles with a low-cost tool capable of providing accurate, high-resolution images of the interior of rotted pole sections. This information, combined with data from other inspection methods, can provide a more thorough assessment of pole condition to be used in a pole management program. If our feasibility study shows promise, LLNL intends to seek partners for technology and product development and, ultimately, licensing for manufacture.

LLNL's radar imaging technology and system concepts developed for bridge deck inspection are directly applicable to other underground imaging problems like mapping buried utilities. While the radar used for bridge deck inspection uses very low power levels and penetrates only to depths of about 12 inches in concrete, the imaging algorithms can be used directly with higher power radars designed to achieve greater penetration depths. For example, these algorithms have been used with another LLNL-designed radar system for detecting and imaging land mines and other objects buried in soil to depths of greater than 1/2 meter. In that radar, the antennas were located at a slant range of 10 meters from the target area and operating with a peak power of ~245 kW. Our current assessment is that a radar system, operating at close range to the target area (< 1 meter above the surface) and at relatively low power (< 1 kW, peak), can be designed to penetrate to depths of 2 to 4 meters in a wide range of soil types and conditions to provide data with adequate resolution for underground utility mapping.

We have outlined a low-cost evaluation project that would assess the improvements our imaging algorithms could provide when used with commercially-available GPR systems used for underground utility surveys. Our approach in this program would be to use electromagnetic modeling and controlled laboratory and field experiments to perform the evaluation. LLNL is seeking to communicate with interested parties regarding this evaluation project.

Finally, it is possible that there are other applications for these technologies in the utility industry of which we are not aware. We would welcome your suggestions or inquires in that regard and are prepared to discuss your application requirements.

For further information, please contact:
John Warhus
Lawrence Livermore National Laboratory
P.O. Box 808
Mail Stop L-153
Livermore, CA 94551
510-423-2783 (voice)
510-423-5080 (fax)
jwarhus@llnl.gov (email)

Topics: T&D