CCTV Is Tried and True

Video inspection remains the standard for CIPP assessment, but supplementing with other technologies can provide more accurate results.

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I  eagerly anticipate learning more about new trenchless technologies as I gear up for this month’s WEFTEC and other conferences in early 2018. Over the years, we have seen products and services evolve to deliver best-in-class solutions for the inspection, maintenance and repair of underground infrastructure, advancing our mission to ensure the continued acceptance and growth of trenchless technologies.

Traditional closed circuit television is one example of a technology that has both evolved and been challenged over the years. NASSCO is often asked about the use of alternative technologies to CCTV, specifically for the inspection of CIPP installations, and for the past 30 years the answer has not changed: Only visual inspection and CCTV can accurately identify observations and defects that affect installation (preconstruction) and acceptance (post-construction) of CIPP projects.

With CCTV, the operator is able to see and record the entire rehabilitated sewer from manhole to manhole. This includes checking the quality of service lateral reconnections as well as checking for leaks and identifying defects. That being said, there are many exciting technologies that work to supplement traditional CCTV for more accurate assessment results, including:

  • Laser profiling: This technology provides very accurate shape and condition data for the internal wall of the pipe being inspected. These systems are typically utilized to report pipeline deflection, deformation, ovality and changes in cross-sectional areas, and are also used to estimate wall deterioration (loss of thickness of the pipe wall), principally in concrete sewers.
  • Laser diode measurement tools: Utilized by pipeline inspectors to measure defects inside the pipe during normal CCTV inspections, these tools are used for crack and fracture measurement, joint openings, and other issues of concern that need precise measurement to provide proper perspective and accurate data to the engineer in order to establish condition benchmarks for existing pipe and acceptability of new pipe.
  • Sonar: The sonar profiler is designed to provide dimensional data on debris levels, grease accumulation, pipe deformation and other anomalies below water level, where visual inspection cannot be used. In surcharged lines or siphons, sonar can provide the profile and dimensional data of significant obstacles or defects.
  • Sidewall scanning: These panoramic inspection systems utilize digital imaging cameras to capture a continuous 360-degree image of the inside wall of a pipeline. The data images can be post-processed to provide defect measurements for cracks, joint openings and other issues.
  • Zoom camera technology: Inspections using this technology are intended to quickly obtain enough data to develop a preliminary diagnosis of the pipe condition from images taken only from the manhole or another point, providing a general overview of the condition of the pipe, observable from the access points.
  • Pipe-penetrating radar: This technology works similar to “ground-penetrating radar” in that electromagnetic waves are sent through the pipe wall from within the pipe to identify exterior voids, approximate wall thickness (plus or minus 10 percent), presence of reinforcement steel, exterior repair couplings and changes in soil or water content to a distance of 3 feet.

These and other emerging technologies — including acoustic inspection devices or tools, conductivity measurements from pipe to surface, and the use of microwaves used to identify taps in CIPP — may prove to be excellent complements to traditional CCTV. It is important, however, to steer clear of any marketing message that purports a product or service to be the best (or only) solution. Every project is unique, and every job will benefit from traditional CCTV, supplemented with appropriate technologies to provide the most definitive inspection results possible.

NASSCO will continue to partner with academia, specifically the Trenchless Technology Center at Louisiana Tech, and the Center for Underground Infrastructure Research and Education at the University of Texas –Arlington, as these organizations evaluate and grow the acceptance of new innovations in trenchless assessment, maintenance and repair.


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