Building a Defensible Framework for Prioritizing Water Main Rehabilitation James Carolan and Replacement. March 21, 2012

Transcription

1 Building a Defensible Framework for Prioritizing Water Main Rehabilitation James Carolan and Replacement March 21, 2012

2 The Challenge Challenge - How do you effectively balance infrastructure growth, upgrades and replacement, within your available budget? Solution - Identify, then upgrade and/or replace highest risk assets first, right? but it s not that easy How do you know if your strategy is keeping up with the degradation of your assets? How much is enough? How do you assign and prioritize asset risk? Which pipes are a your riskiest? How do you manage the plan long term? How to integrate capital planning with your enterprise?

3 Past Solutions Target leaking or obviously failing assets Line or replace the old stuff Look at past breaks and try to identify bad areas Keep your ear to the ground advanced leak detection

4 The New Approach Use hydraulic criticality from a hydraulic model Use GIS for consequence analysis Use statistical tools for failure forecasting Age and break analysis Corrosion & soils analysis (GIS) Stray current analysis Manage the data and the plan in capital planning software Integrated with GIS and other systems (CMMs, etc)

5 The New Approach is a Continuous Process GIS Data Anecdotal Data Hydraulic Model Field Samples O&M Data Management Strategies Defensible & Sustainable Capital Planning LEYP/GompitZ (Care-W & Care-S) KANEW Spreadsheets CapPlan Riva Modeling Capital Plans ARP Annual Renewal Planning

6 GIS The New Approach Basic Toolkit Can help assemble data from multiple sources and do spatial analysis, but no hydraulics Hydraulic Modeling Software Useful for seeing the consequences of a hydraulics failures, but unable to build models that encompass non-hydraulic data (breaks, condition, etc.) Computerized Maintenance Management Software (CMMS) Source of failure and performance data, but not able to do modeling using multiple factors Capital Planning and Management Software Pull all these data together then develop and manage your plan long term Better integrated with the organization than past paper reports or long term studies

7 The New Approach Advanced Toolkit Statistical Analysis Tools - LEYP Advanced review of historic pipe failure data What types of pipe are failing and why Provides better estimate of pipe condition system wide Macro Modeling Tools - KANEW How do we know how much to do each year and of what type? Use pipe life spans and pipe inventory to develop long range plans

8 Leverage GIS and Hydraulic Model Fluid Age/Chemistry Historic Shorelines Economic Zones Critical Users Roads and Tunnels Hydraulic Criticality

9 GIS - Automated Service Generation Automated service placement to nearest main Determined demands for water model Not 100% perfect, but significantly improves accuracy of demand allocation Used in water outage analysis Link your customers to your model/gis

10 GIS - Soil Data Overlay main breaks on Fill areas Soil types Corrosive soils vs Break Locations

11 GIS - Flood Risk Analysis Locate sensitive locations Hospitals Schools High use roadways Critical facilities Use topographical data to develop flow sheds What areas will drain to the sensitive location? Overlay sheds with mains and sensitive locations Determine which mains breaks may flood a sensitive location

12 HM - Hydraulic Criticality Hydraulic model based on GIS can identify problem areas Pipes where failure results in loss of service Areas that are only served by one pipe Extent of outage area resulting from pipe failure

13 HM - Automated Valve Isolation Tracing Valve shutoff for single main failure affects multiple pipes and buildings Analyze and rank each main feature Identify mains that would effect sensitive customers

14 HM - Water Age Hydraulic model analysis Identify areas of low flow high residency time Of those identify older pipes non-lined pipes Query water quality complaints from work orders Correlate complaints with hydraulic model results Determine if model accurately predicts water age

15 Example: CapPlan Bringing it All Together Uses existing hydraulic model and GIS Innovyze hydraulic models Esri GIS Performs spatial analysis on the fly Easily builds spatial tests for consequence Use hydraulic modeling results Pressure Water Age Hydraulic Criticality Manages the plan long term

16 CapPlan - Past Break Analysis Proxy for condition Use past breaks to rank assets Each pipe is assigned a value based on number of past breaks Allows each pipe to be compared for break risk against each other But it only ranks pipes with breaks what about the others?

17 The Advanced Tools Taking it the Next Step Statistical Analysis Tools Casses/LEYP Allows failure and GIS data to be assessed simultaneously using advanced statistics Great for determining how different variables (material, age, soil type, etc.) impact each other Used to determine failure probability of each pipe Not just previously failed pipes Macro Modeling Tools - KANEW Looks at pipe renewal rate as a collection over time Relies on user setting service lives for each type of pipe Budget impacts shown over time Does not help decide which specific pipe segments need to be replaced or when

18 Statistical Analysis Asset type Predicted Break Rate [breaks per mile/ year] CI CI CI2R 0.02 CICL 0.11 DICL DICL DICL2R PCI PCI PCI2R 0.02 Advanced regression analysis used to identify contributing factors Identifies strong and weak correlations Provides a predicted break rate for ranking the pipes All pipes in the system get ranked, not just those that have broken Provides an overall guide to pipe life spans

19 # breaks Break rate (breaks/100mi/year) LEYP - Example Use past break history to develop Asset Typesurvival PCI curves Inventory (2009) Break stats ( ) Length [ft]: 1,865,451 ft # Breaks, all pipes: 553 breaks Curves provide a guide to when and what percentage of assets Length [%]: 37 % Break rate, all pipes: 4.89 #/100mi.year will fail over the short and long term Average age 106 years # Breaks, active pipes: 344 Schäden 100%-Age: 82 years Break rate, active pipes: 3.04 #/100mi.year 50%-Age: 102 years 10%-Age: 127 years Trend: Important for macro analysis system wide long term analysis PCI - Breaks and break rate per age Age (years) Ageing parameter Replacement stats ( ) From To not representative 100% Replaced length [ft]: 0 ft 50% Cumulative replacement rate (x years): 0 % 10% Average replacement rate (x years): 0 % Ageing factor a Average age at time of replacement: 0 years Renewal factor b Required age at time of replacement: 0 years Resistance time c % 90% 80% 70% 60% 50% 40% 30% 20% 10% Survival function 0% Age # breaks Break rate (breaks/100mi/year)

20 KANEW Macro Analysis How much should we work on to keep up? Which types of pipe will fail first? What should our mix of rehabilitation vs replacement be? Will rehabilitation help extend our system life? Run scenarios and develop long term approaches

21 The Tools Need Data Data quantity can be an issue Material and age information Joint type and lining information How many previous break records exist? Is there soils data? Data quality can be an issue Accurate GIS data age, material, etc. Are the breaks as points on the pipes? How spatially accurate and well defined are the soil records?

22 Developing a System for Your Agency Build on a good GIS base Good material & age data Add asset management & historical data Type and number of breaks and leak Link between work activity and affected assets Identify risk and performance factors Where failure will impact service? What do you and your customers worry most about? Feed back data to asset database (GIS) Internal procedures Leverage existing and new computer technology

23 Questions?? James Carolan Associate CDM Smith