Pure Technologies - a Xylem brand

Case study - Anderson and Fish Creek PCCP and bar-wrapped force main assessment


Courtesy of Pure Technologies - a Xylem brand

  • Service: SmartBall and PipeDiver
  • Client: The City of Calgary
  • Project Date: December 2011
  • Type of Pipeline: Wastewater Force Main
  • Diameter: 750mm (30-inch)
  • Pipe Material: PCCP and C-303 pipe
  • Length: 12.6km

The City of Calgary is currently planning to reverse the flow direction of two critical wastewater force mains in the city. The flow will be redirected to a new major treatment facility south of the city. Part of the project requires an engineering study to to assess the risk of the operational changes to the pipeline.

A critical part of the study is to collect structural condition information on the pipelines and then use that information to assess the structural capacity. One of the force mains is composed of 750mm (30-inch) prestressed concrete cylinder pipe; the other is composed of 750mm (30-inch) bar-wrapped pipe (AWWA C303). Based on previous success in the City of Calgary with inspecting both PCCP and C303 pipes, Pure was contracted to inspect both of the critical wastewater conduits for the City.

Pure used its PipeDiver electromagnetic (EM) system to perform a non-destructive in-line inspection of the PCCP force main while it remained in service. Prestressing wires are the main structural component of PCCP and as the wires break, the pipe loses its internal loading capacity. The EM system was used to provide a baseline assessment of the pipeline by locating and quantifying the number of broken prestressing wires along the pipeline.

C303 pipe, in contrast to PCCP, acquires its structural capacity from a combination of a thicker gauge wire coil and a thicker gauge steel cylinder. An inspection of both the wire and cylinder is required to provide baseline information on C303 pipe and Pure re-configured the PipeDiver system in order to accomplish this. This enhanced-EM system was used to locate and quantify broken wires along the pipe, but in addition, it scanned the steel cylinder to identify large areas of corrosion (i.e. wall thinning). Again, the PipeDiver system provided a in-line method of inspecting the pipeline while it remained in service.

The data from the inspections will be utilized by CH2M HILL and the City of Calgary to determine if the flow reversal project can go ahead as planned.

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