WRF Webcast Selecting Cost-Effective Condition … Municipal Utilities Authority (EMUA), New Jersey Colorado Springs Utilities (CSU), Colorado WaterOne, Kansas City of Ottawa, Ontario
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2. Examples of data on costs, inspection techniques, their estimated costs, and Weibull parameters.
3. Illustrate framework tool, PIDA (Pipeline Inspection Decision Analyzer) with overview, data requirements and information that helps utilities to make decision on inspection strategies by way of detailed discussion on 1 of 15 selected case studies submitted by water utilities.
San Diego County Water Authority (SDCWA), California
Tarrant Regional Water District (TRWD), Texas
Evesham Municipal Utilities Authority (EMUA), New Jersey
Colorado Springs Utilities (CSU), Colorado
WaterOne, Kansas
City of Ottawa, Ontario
City of Calgary, Alberta
Halifax Water, Nova Scotia
Russell NDE Systems, AlbertaEchologics Engineering, Ontario_____________________________________________________________None of these analyses are possible without good data collection practices.
General objective: Investigate and quantify cost-effectiveness of inspection/condition assessment for high consequence mains.
• Strategy to determine a cost-effective course of action will include:o preventative renewal/rehabilitation of at-risk segments, selection
and implementation of the most appropriate condition assessment technique, determine expected pipe end-of-life, schedule the next pipe inspection/condition assessment.
• Compile library of parameter values
• Present case studies to demonstrate how the proposed framework could be effectively applied in various circumstances.
The main benefit of water main inspection is to identify imminent failures and convert them from catastrophic(high-cost) to manageable (low-cost).
The expected number of catastrophic failure interceptions varies over the life of the pipelines: the more deteriorated, the more potential catastrophic failures are expected.
Inspection makes sense if the cost to inspect is lower than the expected cost savings of failure interception (provided the pipeline has not reached the end of its useful life).
• Pipeline – collection of relatively homogeneous pipe segments (bell-to-spigot).
• Pipe segment failure - occurs when a single pipe segment fails, resulting in segment renewal (replacement or rehabilitation).
• Segment time-to-failure – pipe segments comprise a statistical population assumed to have a probability distribution (Weibull) of time-to-failure.
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Failu
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Segment age
Faster deterioration
Slower deterioration
Source: Rajani, B., and Y. Kleiner. 2017. Selecting Cost-Effective Condition Assessment Technologies for High-Consequence Water Mains. Project #4553. Denver, Colo.: Water Research Foundation.
• Pipe segment (minor) repair –restores the pipe segment to as good as old (clamped small leaks, re-caulked joint leaks, etc).
• Pipe segment rehabilitation (unscheduled) - upon failure, the pipe segment can be repaired/replaced, restoring it to as good as new.
• Pipe segment rehabilitation (scheduled) - undertaken following discovery of imminent failure (interception). Pipe segment restored to as good as new.
Failure cost (consequence) includes direct, indirect and social costs:
• Pipeline inspection – includes inspection planning, mobilisation, implementation and interpretation of results to identify imminent failures.
• Pipe segment imminent failure – determined by inspection (failure almost certain to occur before next inspection).
• Probability of detection (POD) - as no inspection technology is perfect, there is some likelihood that an imminent failure will not be identified.
• Probability of false positive (PFP) – probability that an inspection will erroneously identify an imminent failure.
• Validation of inspection results – a pipe segment identified as imminent failure is re-examined closely before rehabilitation/replacement is undertaken.
• Inspection cycle ─ duration between subsequent inspections. It is assumed that an inspection session can reveal with reasonable confidence imminent failures anticipated during the cycle.
• Pipeline (economic) end-of-life - when it is more economical to replace the entire pipe rather than continue to perform scheduled and unscheduled segment renewals.
Source: Rajani, B., and Y. Kleiner. 2017. Selecting Cost-Effective Condition Assessment Technologies for High-Consequence Water Mains. Project #4553. Denver, Colo.: Water Research Foundation.
Source: Rajani, B., and Y. Kleiner. 2017. Selecting Cost-Effective Condition Assessment Technologies for High-Consequence Water Mains. Project #4553. Denver, Colo.: Water Research Foundation.
• Compute the expected number of failures.• Inspection will reveal a portion (POD-dependent) of existing
imminent failures.• Detected imminent failures are validated and segments are
replaced if necessary.
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Exp
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Pipeline age
Inspection (POD) Detected imminent failures
Undetected imminent failures
Source: Rajani, B., and Y. Kleiner. 2017. Selecting Cost-Effective Condition Assessment Technologies for High-Consequence Water Mains. Project #4553. Denver, Colo.: Water Research Foundation.
• Compute the expected number of failures.• Inspection will reveal a portion (POD-dependent) of existing
imminent failures.• Revealed imminent failures are validated and segments are
replaced if necessary.
Expected cost of inspection cycle of duration t years =(expected # of failures • failure cost) +(expected # of failures avoided • renewal cost) +(expected # validations • validation cost) +cost of inspection
Direct (monetary) benefit of inspection =(expected cost of failures over t years with no inspection) -
Source: Rajani, B., and Y. Kleiner. 2017. Selecting Cost-Effective Condition Assessment Technologies for High-Consequence Water Mains. Project #4553. Denver, Colo.: Water Research Foundation.
Source: Rajani, B., and Y. Kleiner. 2017. Selecting Cost-Effective Condition Assessment Technologies for High-Consequence Water Mains. Project #4553. Denver, Colo.: Water Research Foundation.
Source: Rajani, B., and Y. Kleiner. 2017. Selecting Cost-Effective Condition Assessment Technologies for High-Consequence Water Mains. Project #4553. Denver, Colo.: Water Research Foundation.
Source: Rajani, B., and Y. Kleiner. 2017. Selecting Cost-Effective Condition Assessment Technologies for High-Consequence Water Mains. Project #4553. Denver, Colo.: Water Research Foundation.
After every update re-compute pipeline remaining life.
Updating Pipe Condition (1)
Inspection provides distress indicators pointing to imminent failures.
Continual field-data about the pipeline condition are obtained from: • Actual (historical and current) failures.• Existence of imminent failures (from inspection).• Number of pipe segments survived to date.
Use a detailed Bayesian-updating process to update the time-to-failure probability distribution parameters.
Example: Pipeline installed 1945, analysed in 2013, 100 segments. Semi-informative parameters determined by expert opinion.
Source: Rajani, B., and Y. Kleiner. 2017. Selecting Cost-Effective Condition Assessment Technologies for High-Consequence Water Mains. Project #4553. Denver, Colo.: Water Research Foundation.
• In 1985 complete inspection found one imminent failure.
• In 1995 opportunistic inspection revealed imminent failure in one segment.
• In 1999 bell split (failure).
• In 2005 complete follow-up inspection revealed imminent failure in one segment.
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Updated
Updating Pipeline Condition (3)
Source: Rajani, B., and Y. Kleiner. 2017. Selecting Cost-Effective Condition Assessment Technologies for High-Consequence Water Mains. Project #4553. Denver, Colo.: Water Research Foundation.
Trunk main correlator ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ EchoShore®)-Mobile Leak detection. 50% 0.15% $15,000 $2 / ft ($7 / m)
Acoustic resonance ✓ ✓ ✓ ✓ Breivoll ART Detailed thickness profile, pipe topography and detects and distinguishes between internal and external corrosion. Also detects leakage.80% 0.30% $11-21 / ft ($35-70 / m)
Acoustic propagation velocity ✓ ✓ ✓ ✓ ✓ ✓ ePulse® Average remaining wall thickness (hoop stiffness for PCCP and Bar-wrapped).70% 0.06% $15,000 $5 / ft ($16 / m)
Acoustical Long-Term Monitoring
Fixed leakage monitoring systems ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ EchoShore-TX Detection of leaks as they occur. 50% 0.15% $15,000 $8 / ft ($26 / m)
Acoustic emissions monitoring (hydrophones, fiber optic) ✓ EchoShore-TX, SoundprintDetection of wire breaks as they occur. Immenent failure warning possible.90% 0.06%
Inspection TechnologiesCast iron -
pit
Cast iron -
spun
Ductile
ironSteel
Bar-
wrappedPCCP
Reinforced
concreteHDPE
Trade (proprietary) name
for specific technologyDescription of capabilities
Probability of
detection (POD)
of imminent
failures
Probability of
false
positives
(PFP)
Typical
mobilization & de-
mobilization costs
($)
Range of inspection
costs / unit length
Visually based
Internal - Man entry and visual inspection ✓ ✓ ✓ ✓ ✓ ✓ ✓ PCWI 30kV Visual photography, coating
assessment detect longitudinal cracks
20% 0.12% $20,000 - $30,000 $12 / ft ($39 / m)
Internal - CCTV inspection ✓ ✓ ✓ ✓ Sahara, JD7 Useful for spalling of cement mortar
Trunk main correlator ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ EchoShore®)-Mobile Leak detection. 50% 0.15% $15,000 $2 / ft ($7 / m)
Acoustic resonance ✓ ✓ ✓ ✓ Breivoll ART Detailed thickness profile, pipe topography and detects and distinguishes between internal and external corrosion. Also detects leakage.80% 0.30% $11-21 / ft ($35-70 / m)
Acoustic propagation velocity ✓ ✓ ✓ ✓ ✓ ✓ ePulse® Average remaining wall thickness (hoop stiffness for PCCP and Bar-wrapped).70% 0.06% $15,000 $5 / ft ($16 / m)
Acoustical Long-Term Monitoring
Fixed leakage monitoring systems ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ EchoShore-TX Detection of leaks as they occur. 50% 0.15% $15,000 $8 / ft ($26 / m)
Acoustic emissions monitoring (hydrophones, fiber optic) ✓ EchoShore-TX, SoundprintDetection of wire breaks as they occur. Immenent failure warning possible.90% 0.06%
Trunk main correlator ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ EchoShore®)-Mobile Leak detection. 50% 0.15% $15,000 $2 / ft ($7 / m)
Acoustic resonance ✓ ✓ ✓ ✓ Breivoll ART Detailed thickness profile, pipe topography and detects and distinguishes between internal and external corrosion. Also detects leakage.80% 0.30% $11-21 / ft ($35-70 / m)
Acoustic propagation velocity ✓ ✓ ✓ ✓ ✓ ✓ ePulse® Average remaining wall thickness (hoop stiffness for PCCP and Bar-wrapped).70% 0.06% $15,000 $5 / ft ($16 / m)
Acoustical Long-Term Monitoring
Fixed leakage monitoring systems ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ EchoShore-TX Detection of leaks as they occur. 50% 0.15% $15,000 $8 / ft ($26 / m)
Acoustic emissions monitoring (hydrophones, fiber optic) ✓ EchoShore-TX, SoundprintDetection of wire breaks as they occur. Immenent failure warning possible.90% 0.06%
Inspection TechnologiesCast iron -
pit
Cast iron -
spun
Ductile
ironSteel
Bar-
wrappedPCCP
Reinforced
concreteHDPE
Trade (proprietary) name
for specific technologyDescription of capabilities
Probability of
detection (POD)
of imminent
failures
Probability of
false
positives
(PFP)
Typical
mobilization & de-
mobilization costs
($)
Range of inspection
costs / unit length
Visually based
Internal - Man entry and visual inspection ✓ ✓ ✓ ✓ ✓ ✓ ✓ PCWI 30kV Visual photography, coating
assessment detect longitudinal cracks
20% 0.12% $20,000 - $30,000 $12 / ft ($39 / m)
Internal - CCTV inspection ✓ ✓ ✓ ✓ Sahara, JD7 Useful for spalling of cement mortar
Trunk main correlator ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ EchoShore®)-Mobile Leak detection. 50% 0.15% $15,000 $2 / ft ($7 / m)
Acoustic resonance ✓ ✓ ✓ ✓ Breivoll ART Detailed thickness profile, pipe topography and detects and distinguishes between internal and external corrosion. Also detects leakage.80% 0.30% $11-21 / ft ($35-70 / m)
Acoustic propagation velocity ✓ ✓ ✓ ✓ ✓ ✓ ePulse® Average remaining wall thickness (hoop stiffness for PCCP and Bar-wrapped).70% 0.06% $15,000 $5 / ft ($16 / m)
Acoustical Long-Term Monitoring
Fixed leakage monitoring systems ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ EchoShore-TX Detection of leaks as they occur. 50% 0.15% $15,000 $8 / ft ($26 / m)
Acoustic emissions monitoring (hydrophones, fiber optic) ✓ EchoShore-TX, SoundprintDetection of wire breaks as they occur. Immenent failure warning possible.90% 0.06%
Source: Rajani, B., and Y. Kleiner. 2017. Selecting Cost-Effective Condition Assessment Technologies for High-Consequence Water Mains. Project #4553. Denver, Colo.: Water Research Foundation.
Source: Rajani, B., and Y. Kleiner. 2017. Selecting Cost-Effective Condition Assessment Technologies for High-Consequence Water Mains. Project #4553. Denver, Colo.: Water Research Foundation.
Romer et al. (2008) Failure of PCCP – WRF (parameters re-derived from data).
Source: Rajani, B., and Y. Kleiner. 2017. Selecting Cost-Effective Condition Assessment Technologies for High-Consequence Water Mains. Project #4553. Denver, Colo.: Water Research Foundation.
Source: Rajani, B., and Y. Kleiner. 2017. Selecting Cost-Effective Condition Assessment Technologies for High-Consequence Water Mains. Project #4553. Denver, Colo.: Water Research Foundation.
Source: Rajani, B., and Y. Kleiner. 2017. Selecting Cost-Effective Condition Assessment Technologies for High-Consequence Water Mains. Project #4553. Denver, Colo.: Water Research Foundation.
Sensitivity: If inspection cost is reduced to $270K (< 25%)
Source: Rajani, B., and Y. Kleiner. 2017. Selecting Cost-Effective Condition Assessment Technologies for High-Consequence Water Mains. Project #4553. Denver, Colo.: Water Research Foundation.
Sensitivity: If failure cost is x 7 = $560K & POD is 0% (No inspection)
Source: Rajani, B., and Y. Kleiner. 2017. Selecting Cost-Effective Condition Assessment Technologies for High-Consequence Water Mains. Project #4553. Denver, Colo.: Water Research Foundation.
Source: Rajani, B., and Y. Kleiner. 2017. Selecting Cost-Effective Condition Assessment Technologies for High-Consequence Water Mains. Project #4553. Denver, Colo.: Water Research Foundation.
• PIDA (Pipe Inspection Decision Analyzer) tool is an aid based on the developed framework to make a business case.
• Available data often imprecise and vague hence it is important to take the time to establish credible input values.
• Good practice to conduct sensitivity study for those input data or parameters where some uncertainties exist, e.g., cost of failure (location, location, location, ...), cost of inspection, probability of detection (POD), probability of false positives (PFP), etc.
• PIDA does not obviate the need for good engineering and economic judgment!