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116 <br />WATER RATE STUDY I City of Santa Ana, CA <br />Consequence of Failure Analysis (CoF) <br />In order to assess the criticality of each pipe segment for use in risk based prioritization, a set of criteria <br />(rules) were required that reflect the relative importance of each pipe section in terms of delivery of <br />levels of service (serviceability), economics and health and safety. A risk workshop was held with City <br />staff on May 31, 2012 to identify likely criticality factors and their relative importance. Although several <br />possible criteria were suggested, some could not be used due to lack of sufficient source data or were <br />beyond the scope of this study. In a process similar to the PoF analysis, criteria for the Consequence of <br />Failure (CoF) were then identified and evaluated. These criteria are described below. <br />Pipe Diameter <br />Primarily, the consequence of any given pipeline failing is related to the number of customers which are <br />directly served, the impact of that pipeline on the overall hydraulics of the system and the impact of that <br />main break from a safety standpoint. Without a hydraulic model to assess the hydraulic criticality of <br />each pipeline, the most effective proxy available in the existing data is simply pipe diameter. The <br />assumption used is that the consequence of a larger main failing is more significant than that of a <br />smaller main, plus the repair cost will likely be greater. Pipe diameter was used as 100 percent of the <br />initial CoF score and defined as shown in Figure B - 29 below. <br />Figure B - 29: Water System Pipelines CoF Scores by Diameter <br />Critical Customer Impacts <br />In addition to the diameter of each main, the proximity of each main segment to critical customers (such <br />as hospitals, schools and government buildings) was also utilized in order to increase the initial CoF <br />Score. The concern here is for increased risk due to possible environmental and inconvenience to nearby <br />critical customers. The City provided tabular lists of critical customer locations. These sites were <br />geocoded by address data (if available) to identify the customer's location on a map. Using GIS spatial <br />processes, all mains within a 300 foot radius of each critical site was tagged. A count of nearby sites was <br />then tabulated for each main segment. Note, other methods could be used to identify the impact of <br />nearby critical customers. However, based on the source data available, this approach was the most <br />logical. The initial CoF Score (diameter) was then adjusted as follows: <br />65B -128 <br />NOVEMBER 2014 <br />