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112 <br />WATER RATE STUDY I City of Santa Ana, CA <br />Repeated Failures <br />Finally, while the Pipeline Cohorts and Age make up the overall PoF data, City staff mentioned that in <br />many instances, pipelines that have failed in the past have experienced multiple failures. Therefore, pipe <br />segments that have had more than one recorded break since 1990 had their individual PoF score <br />increased by 2. Pipes which have had one recorded break since 1990 had their PoF score increased by 1. <br />Pipes with no recorded breaks since 1990 had their PoF Score determined solely by their Cohort and <br />Age. Resulting PoF scores were limited to not exceed 10. <br />Other PoF Considerations <br />Several other physical properties and environmental conditions were considered for inclusion in this <br />analysis. Some of them are addressed below. Although these factors were not actually used in the PoF <br />prioritization analysis, they may someday provide useful information. Therefore, the City is encouraged <br />to reevaluate these once their Asset Management system is more mature. <br />• Mains by Diameter: There does not appear to be any obvious correlation of water pipe failure <br />and pipe diameter. Therefore, this aspect was not considered for PoF calculations. <br />• Depth of burial: Data not available. <br />• Heavy street traffic: Data not available. <br />• Operating Pressure: Hydraulic modeling data not available. <br />• Soils: A high level review did not reveal any obvious correlation of high break concentrations for <br />water pipe to key soil characteristics. However the City may want to further review these <br />considerations in the future. <br />Overall PoF Calculation <br />To produce an overall PoF score for individual pipe segments, weighted scores for each of the <br />contributing PoF criteria were added together. The resulting PoF scores are, by design, within the range <br />of 0 to 10. For simplicity, the three PoF criteria were all assigned the same weighting (level of <br />importance). By adjusting these weights other assessment scenarios could be created. Table B - 9 below <br />provides a summary of the PoF criteria used in this analysis. <br />[SPACE INTENTIONALLY LEFT BLANK] <br />65B -124 <br />NOVEMBER 7014 <br />