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 Region of Peel Trunk Sewer Inspection and Condition Assessment Program: A Multi-level, Staged Approach Mark Andrews, P.Eng., Andrews Infrastructure, Ottawa, Canada Overview Subject: Trunk Sanitary Sewer, Operations and Management Keywords: condition assessment, trunk sanitary sewers, CCTV inspection The Regional Municipality of Peel is located on the west side of the City of Toronto adjacent to Lake Ontario. Peel’s wastewater scheme consists of 2 major drainage systems (the East and West systems) each of which outlets to a treatment plant located on the shores of Lake Ontario. The lake-based wastewater system currently services approximately 1 million people. In 1997 the Region commenced a pilot program to inspect two large diameter trunk sanitary sewers using combined Closed-circuit Television (CCTV) and Sonar equipment. Successful completion of the pilot program lead the Region to initiate a comprehensive Trunk Sewer Inspection and Condition Assessment Program to address the needs of the entire trunk sewer system. This involves some 210 km of pipes ranging in size from 750 mm to 3050 mm in diameter (see summary in Table 1). Based on known needs and available technology a multi-year, staged program was developed. Approximately 50,000 m of pipeline and some 500 structures have been inspected each year since 1997. Stage 1 of the annual program involves an initial “First Order” inspection of the assigned sewers and manholes for that year. In Stage 2, assets are rated according to a defined set of criteria, needs are identified and priorities ranked. For the most part condition assessment results are clear cut with the majority of pipelines and structures found to be in good condition while only a few need obvious repair or rehabilitation. However, in some cases the implications of the First Order inspections are not obvious and further detailed investigations are warranted in order to finalize condition assessment conclusions; these detailed, “Second Order” investigations are carried out in Stage 3. Selecting from a menu of available techniques, detailed investigations are tailored to suit site specific problems and objectives. These have involved in-depth hydraulic analysis, monitoring of corrosive environments, person-entry inspections, concrete coring and detailed structural investigations. The Stage 3 findings are then used to finalize and update the Stage 2 condition assessment rankings. Finally, in Stage 4, findings are compiled and feasible remedial techniques are programmed into the next year’s Capital Budget. The purpose of this paper is to explain the importance of a systematic and proactive approach for managing large diameter trunk sewers. The paper highlights how this program has evolved to become an important tool in developing and prioritizing the Region. |
