Lessons Learned Mapping Critical Pressure Pipelines: City of Ottawa Case Studies

The City of Ottawa is a municipality of 960,000 people that owns and operates its own watermain and sewer infrastructure. The City has developed industry-leading comprehensive asset management strategies for its pipe infrastructure. A key element of the management strategy for its critical pressure pipes-the large-diameter watermains (24 in. to 78 in.) and sewer force mains (all sizes up to 42 in.)-includes mapping. Pipeline mapping is a useful tool for addressing distress and managing the asset. However, when trying to correlate internal pipe conditions to above ground coordinates, a number of challenges arise, particularly when defects are identified as a part of the condition assessment. In order to effectively intervene on a distressed pipe, it is critical to be able to locate and excavate that pipe with certainty. Errors in mapping can lead to erroneous excavations, costing the City valuable time and money. In order to overcome this challenge, a variety of technologies and methodologies have been utilized to map the City’s pipelines. To date the City has completed over 24.2 mi of 2-dimensional mapping using a combination of above ground GPS points and internal pipe data collected as part of the condition assessment work. Different inline inspection tools were used to collect the data required to create the maps, including tethered and free swimming tools, depending on the inspection requirements. This paper will discuss the methods used to create the GIS data of the over 24.2 mi of pipeline; the benefits to having the mapping data; lessons learned while trying to use the map; comparisons between the inspection GIS and the City’s GIS; as well as overall challenges with mapping pipelines in general.