65B - PROPOSED WATER AND SEWER RATE ADJ

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City of Santa Ana, CA I �1JATER RATE STUDY Pipe Vintage (Age) Although the Pipe Cohorts were the single most critical aspect of the PoF Score, it was important to also consider the age of a pipeline without regard for material. As shown in Figure B - 26 below — which displays the number of breaks per 100 miles per year since 1990 for water system pipelines installed in each decade — pipes installed prior to 1940 were shown to have more than 6 breaks per hundred miles per year. For pipes installed after 1940, the number of breaks per hundred miles per year steadily decreased based on installation year, from more than 4 for pipes installed in the 1950s to less than 1 for pipes installed in the 1990s and 2000s. Figure B - 26 provides a map of water mains highlighting those pipes that have not had CCTV inspections. Depending on the asset management strategy used, the City may want to target future inspections on those uninspected mains or on those mains having high -risk conditions. Performing repeated inspections every few years provides valuable insight into the rate of change. Figure B - 26: Water Pipeline Historical Break Rate by Installation Decade Because the age of the pipelines clearly plays an integral role in the overall probability of a failure occurring, pipeline installation year was included as 40 percent of the initial PoF Score. Pipe age considerations were assigned as follows: • Pipes installed before 1940 were assigned a score of 10 • Pipes installed in 1940 or after were assigned a decreasing linear score from 10 to 1 • 1970s and 1980s Ductile Pipe was considered 0 percent BLACK &VEATCH I Appendix8: Water CIP Prioritiza?lo,� P, -1 -',s 65B -123 111