Television and Scanning Sonar in Seattle Metro's Siphons and Brick Sewersby Roger Browne, Municipality of Metropolitan Seattle, (METRO), Seattle, United States,
Graham Knott, Municipality of Metropolitan Seattle, (METRO), Seattle, United States,
Abstract: Comprehensive and often costly investigations are required in order to identify performance deficiencies of the pipeline in sewer systems, particularly when sewers in excess of 48-inch diameters are involved. In Seattle Metro's experience, conventional remote inspection techniques, including Closed Circuit Television (CCTV), had proved inadequate for identifying structural defects and deformation in the larger sewers. Therefore, in 1988, Brown and Caldwell was called upon to conduct predesign investigations, including detailed walkthrough inspections. Considerable flow reduction and safety precautions were required for the walkthrough inspections. Moreover, flow conditions in the large Seattle sewers frequently restricted access, and it some cases excluded it altogether. Therefore, alternative inspection technology, including state of the art CCTV equipment, pipe-profiling sonar, and the 'Sonic Caliper', was examined. Use of such equipment allows the inspection to be undertaken without many of the restrictive safety considerations of walkthrough inspections and at considerably less cost. The paper describes previous inspection methods, including the procedures used for walkthrough inspections. Use of innovative inspection technology and procedures is discussed, and examples of the results presented. Additional developments required to further improve the remote inspection technology are identified.
Subject Headings: Inspection | Siphons | Sewers | Imaging techniques | Bricks | Equipment and machinery | Safety | Defects and imperfections | Sewer pipes | Pipe sizes | Subways | Washington | North America | United States | Seattle
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