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City of Santa Ana, CAI SLWER RAT' E STUIOY <br />Table B - 2: Summary of PoF Criteria used in this Analysis <br />PoF Criteria <br />Weight <br />Comment <br />Strategy / Assumption <br />Cohort Rank (1- <br />33% <br />Assigned values 1 -5 <br />Cohort 5, High: All sewer pipelines installed before 1946 <br />5 values) <br />range, multiply by 2 <br />Cohort 4, Med -High: All pipes with an unknown installation year <br />to get values 1 to 10 <br />Cohort 3, Med: All pipes (except PVC and High Density Polyethylene) <br />installed between 1946 and 1975 <br />Cohort 2, Med -Law: All pipes (except PVC and High Density <br />Polyethylene) installed after 1975 <br />Cohort 1, Low: All PVC and High Density Polyethylene pipes installed <br />after 1946 and any pipes which have been lined since their original <br />installation <br />Raw QSR <br />33% <br />Raw values 0 -5 <br />Considers only the highest grade (worst defect) only and assigns that <br />Grading <br />range, multiply by 2 <br />value to the entire pipe segment. Does not consider the number of <br />Method (0 -5 <br />to get values 0 to 10 <br />defects or lower grade defects observed. Lined pipe ranked at 0 <br />values) <br />(assumed to be "fixed"). Missing QSR data replaced by Cohort Rank. <br />Overall QSR <br />33% <br />Calculated: Divide by <br />Uses a PACP formula of multiplying both rank scores times the number <br />Segment Score <br />16.1 to get decimal <br />of occurrences to identify a total risk factor for the pipe segment (i.e. <br />Method (0 -161 <br />values 0 to 10 <br />considers the number of defects — not just the grade of the worst <br />values) <br />defect). Lined pipe ranked at 0 (assumed to be "fixed "). Missing QSR <br />data replaced by Cohort Rank. <br />Total (sum of <br />100% <br />The resulting PoF <br />above) <br />scores are 0 to 10. <br />By applying the weighting described above (1/3 Cohort Score, 1/3 Raw QSR, and 1/3 QSR Segment <br />Score) to each of the 8,706 active main pipeline segments in the Santa Ana Sewer System, a 0 to 10 PoF <br />Score was calculated for each and the distribution is shown in Figure B 23 below. Figure B 24 provides a <br />map of sewer mains color coded by total PoF score. <br />Figure B- 23: Distribution of Sewer Pipeline PoF Scores <br />BLACK & VEATCH I Appendix B: Sewer CIP Prioritization Proress <br />65B -256 <br />