How confident are you in the spatial data relating to your underground infrastructure? Is it based on 50-year-old as-built records, or worse? An asset management database is only as good as the data with which it is populated. Do you feel confident relying on the information in your database?

The Regional Municipality of Niagara (RMN) - Water and Wastewater Services recently asked itself these same questions and conclude that the spatial data it had available for its water and wastewater underground infrastructure lacked the level of accuracy required to manage its network. RMN decided to look for a better method of populating its database with reliable information that could be used for years to come. The solution to the problem was Subsurface Utility Engineering or SUE, which is a proven method of identifying, locating and mapping underground utility infrastructure. RMN felt the SUE process would provide an excellent, cost-effective method of obtaining reliable information with proven results. The ability to collect data at a variety of quality levels would allow RMN the ability to balance future risks with project cost. In order to test the effectiveness of the process, RMN conducted a pilot project to locate and map approximately 12.1 km of water main, which previously had no as-built records showing their location. The goal of the pilot was to provide a good base for the future collection of additional subsurface infrastructure data.

TSH/TBE Subsurface Utility Engineers join Venture (TSH/TBE) was awarded the contract to complete the pilot project in November 2002. TSH/TBE followed the basic principles laid out in CI/ASCE Standard 38-02 as a guideline for the completion of the project. Using the quality levels defined in the Standard, the goal was to map as much of the project as possible to quality level "B", as well as gather quality level "A" information at key locations.

TSH/TBE began the field collection of data in November 20002 in the St Catharines section, an area with two parallel water mains running down Riverview Boulevard, a residential street in the city. Following the Region's records, the crew began looking for two separate 24" diameter water mains separated by approximately 5m. However, through detailed investigation it was eventually discovered that the two water mains were actually running together stacked one over the other. The position of the water mains was also found to be significantly different from what was first thought; in some areas, they were on the opposite side of the road.

Figure #1. Field Crews completing test holes during winter conditions.

After the SUE field crew completed the designating and test holes for each area, they were followed by the survey crew, who used total station survey equipment (TSS) to precisely survey all the field assets and tie the points to the local coordinate system (UTM). The survey data was forwarded to the CAD operators who converted the information into water main utility drawings using the Region's digital ortho imagery (DOI) raster files as a background for the vector (water main lines) work. The drawings were also converted into ESRI shape files for inclusion in the Region's geographic information system (GIS) geodatabase. The shape files seen in Figure #2, allow a user to see the location of water mains and click on the to obtain details such as size, material type, and depth (at test hole locations). The Region plans to pilot handheld GIS/GPS technology with operations staff to ascertain the effectiveness of this tool. With mobile GIS/GPS technology the information gathered through the SUE process would then be available to field crews.

Overall, the pilot project was very successful. Using SUE principles the project successfully replaced the Region's "poor" spatial information with information that is reliable and accurate. During a recent water main break on a section of main that was included in the investigation, the information proved invaluable for quickly identifying the location of the water main and the valves to shut down the affected section. The SUE process also provided depth information for repair crews that proved to be highly useful, since the water main break was located in a swampy area. In addition, the actual location of this section of water main turned out to be over 100m from where it was thought to lie prior to the investigation. The information from the SUE project was vital in drastically reducing the time required to repair the water main.

The Region of Niagara has now established a method of confidently designating and mapping the location of its existing water and wastewater infrastructure. Using the SUE process allows it the flexibility to collect the appropriate quality level of information for each section. Their progressive approach to this common problem should be applicable in all areas in Ontario and throughout North America.

Credits
Author(s)
Author Not Identified
Written by TSH/TBE

Publication(s)
Underground Focus
Fall/Winter 2003.