CoNTINUED FRoM PAGE 23
WaterOne Applies Foundation Research to Prioritize Pipe Replacements
• Pipe replaceable as part of a city street/sewer improvement project
• Large or critical water user
Each segment of pipe is rated against the criteria on a 5 point scale. All of the criteria are valued programmatically
through the GIS and BMS systems. After the evaluation process is completed, a spreadsheet is developed, which lists
the utility’s entire pipe segments based on the highest to lowest rating. WaterOne’s 2,500 miles of pipe results in
approximately 60,000 pipe segments. Needless to say, attempting to address all 60,000 pipe segments is a daunting
task so the engineering staff evaluates only the top 5% of pipe segments for replacement consideration. The PRPS is
updated yearly to ensure continual evaluation of the pipe segments to be replaced or rehabilitated.
The PRPS process has been successful in helping WaterOne focus on the correct segments of pipe so that its capital
dollars are expended as efficiently as possible. In addition, the PRPS has been used to justify the utility’s pipe
replacement efforts to its governing body and customers as well as the 17 cities served by the utility. When a city or
customer complains about a main break in their city or yard, the utility is able to explain the methodology used to
replace pipe within the system.
For corrosion issues, WaterOne drew upon the WaterRF report called External Corrosion and Corrosion of Buried
Water Mains (2005, order #90987/project #2608). WaterOne believes the root cause of most its main breaks is due
to loss of structural strength of the metallic pipe system due to corrosion. While there are numerous causes of main
breaks such as ground shift from changing soil, moisture content, and frost action to pressure transients, the bottom
line reason the pipe failed, in most cases, is because the structural integrity of the pipe wall has diminished. The loss of
structural integrity of the pipe over the years is generally due to corrosion of the exterior pipe wall. WaterOne started
a corrosion control program, which is still in its infancy, in an attempt to prolong the life of its buried metallic pipe
system. The utility now installs a sacrificial anode whenever it excavates a main for repair or relocation. The utility is
also beginning to evaluate the proactive installation of sacrificial anodes on its existing metallic piping system.
In addition to the projects mentioned above, WaterOne has also referenced Prioritizing Water Main Replacement
and Rehabilitation (2002, order #90898/project #459) for guidance on developing practical and cost-effective
distribution system renewal techniques. The information provided from all these WaterRF reports has helped WaterOne
develop an asset management program suitable for its own unique system.
Deb, A., Y. Hasit, H. Schoser, J. Snyder, G.V. Loganathan, and P. Khambhammettu. 2002. Decision Support System
for Distribution System Piping Renewal, order #90892/project #2519. Denver: AwwaRF and AWWA.
Deb, A. F. Grablutz, Y. Hasit, J. Snyder, G.V. Loganathan, and N. Agbenowsi. 2002. Prioritizing Water Main
Replacement and Rehabilitation, order #90898/project #459). Denver: AwwaRF and AWWA.
Romer, A., G. Bell, S. Duranceau, and S. Foreman. 2004. External Corrosion and Corrosion of Buried Water Mains,
order #90987/project #2608. Denver: AwwaRF.