LOCATING VOIDS BEHIND PIPE WALLS IN LARGE DIAMETER SEWERS USING PIPE PENETRATING RADAR (PPR)

摘要

Large diameter sewers are considered critical assets for most municipalities. Preventing catastrophic sewer failures is probably one of the most challenging issues facing Asset Managers today. The only effective way to view the inside of a large diameter sewer is by undertaking a CCTV camera inspection or by a visual walkthrough inspection, where possible. These methods are effective in locating cracks and structural problems if the lighting and flow conditions are satisfactory. However, these inspection methods only allow us to understand what is happening to the pipe from the inside only, not from behind the pipe wall. If an Asset Manager had the ability to see and understand what is the current condition of the outside of the pipe, they could locate, monitor and make the necessary management decisions to repair possible voids that exist or are forming behind pipe walls before they develop into major catastrophic failures. In 2009, the City of Hamilton undertook a pilot project to develop a multi-array PPR inspection tool to locate voids in large diameter sewers that are greater than 1500 mm in diameter. This paper will review in detail the management decisions around supporting this pilot project. In addition, this paper will describe in detail the man-entry walkthrough PPR trials that were undertaken in a 28 m deep, high flowing 1524 mm combined sewer, and the design, development, construction and successful live trials of a three-channel multi-array PPR inspection tool.