Condition Assessment: Accurate Non-Invasive Measurement of Pipe Wall Thickness OHAWWA Water Distribution Seminar by Dave Johnston Tuesday, July 17

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1 Condition Assessment: Accurate Non-Invasive Measurement of Pipe Wall Thickness OHAWWA Water Distribution Seminar by Dave Johnston Tuesday, July 17 th, 2012

2 The Problem: Water Mains are aging: Approaching or beyond estimated serviceable life. Budgets are tighter: need to maximize the life of buried utilities. Physical condition of the majority of water mains is unknown. How do you choose which mains to prioritize for replacement or rehabilitation?

3 Types of Pipe Cast Iron Turn of the Century Pit Cast Iron Early Spun Cast Iron Thin Walled Cast Iron (post WWII) Asbestos Cement Installed Late 40 s-70 s Early Ductile Iron Concrete (PCCP, RCP etc) Risk Factors: Distribution or Transmission Mains, Location etc.

4 Pipe Wall Condition Assessment 4

5 Condition Assessment What is Condition Assessment? A process or processes that establish a record of the state of the critical aspects of an object at a given time. For cast and ductile iron pipes, a critical aspect is pipe wall thickness and degree pitting corrosion.

6 Condition Assessment Why do Condition Assessment? Find out what condition pipes are in. Estimate remaining serviceable life Prioritize water mains for Rehab or Replacement. Identify water mains that DO NOT need rehab or replacement Avoid Catastrophic Failure.

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9 Condition Assessment How do We Prioritize Capital Spending? Low Hanging Fruit Obvious Choices Indirect Failure history Leakage level Flow testing Soil Analysis Age of Pipe Water Analysis LEYP and KANEW Models

10 Condition Assessment Existing Methods: Direct Visual inspection (e.g., using CCTV probes) Sampling programs Non-destructive testing acoustic emission, RFEC BEM magnetic flux leakage Ultrasonic

11 Condition Assessment Limiting Factors Indirect Analysis do not account for physical condition of the pipe Pipe Sampling Expensive, disruptive, statistically insignificant In-Line Technologies Expensive, Intrusive External Measurements Expensive, mass excavation required Resulting Problems Indirect Analysis Educated Guess In-Line and External: Only limited amounts of pipe can be surveyed and not feasible for smaller diameter mains.

12 Non-Invasive, Non- Destructive Acoustic Assessment Technologies

13 Echologics Pipe Wall Integrity Testing Non-intrusive, Non-disruptive Acoustic Measurements. Uses existing fittings and access points to the pipe. Results in the Average Remaining Pipe Wall Thickness for a given section of pipe. Locates Leaks

14 Leak Detection: Correlation Bracket the leak with two sensors The leak noise takes longer to arrive a point 1 than point 2 Correlator measures this difference and determines the exact leak location

15 Leak Position Determined

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17 Non-Invasive Non-Destructive Assessment Technologies - Background Low frequency acoustic pressure wave is induced in pipe Dominated by a non-dispersive axi-symmetric (S1,n=0) Pressure wave causes pipe wall to flex on microscopic level Thicker (stiffer) pipe walls are more resistant to breathing, causing wave to travel faster Measuring this phenomenon allows calculation of remaining wall thickness

18 Non-Invasive Non-Destructive Assessment Technologies - Velocity Measurement Noise Source Measure the sound velocity Wave propagation velocity (v) = D/ΔT, where ΔT is time delay between signals 1 and 2

19 Velocity Measurement

20 Velocity Equation Where: v = propagation velocity of leak noise in pipe v o = propagation velocity of sound in an infinite body of water D = internal diameter of pipe e = thickness of pipe wall K water = bulk modulus of elasticity of water E pipe = Young s modulus of elasticity of pipe material

21 Condition Assessment Dotted lines represent Minimum band of continuous metal Raised areas cannot carry load

22 Non-Invasive Non-Destructive Assessment Technologies - Implementation Average distance 300 to 500 is optimal, can measure from 100 to 1000 Typically measure between two valves or hydrants Can measure ¾ to 1 mile per day For transmission mains, can vacuum excavate to the crown of the pipe to obtain proper distance Average structural integrity between the two locations is obtained Pipe sampling may be done to confirm results

23 Non-Invasive Non-Destructive Assessment Technologies - Implementation

24 Condition Assessment Echologics Requirements: Pressure No air in pipe Accurate pipe information (maps, as-builts, specs) Access points every ft (ideal). 24

25 Ferrous Water Mains

26 Ferrous Water Mains Cast Iron, Ductile Iron, Steel Physically lose Pipe Wall Thickness AC/DC corrosion Aggressive Soils Aggressive Water Graphitic Corrosion Tuberculation Leaking Joints, pits. Multiple breaks. Echologics Measures the Pipe Wall Thickness

27 Case Studies Hamilton, Ontario Tests were performed at the water distribution system of the City of Hamilton in Ontario. Ten test sites were selected. Selected sites included large and small diameter pipes at different levels of deterioration. All pipes were cast iron.

28 Case Studies Hamilton, Ontario The level of deterioration was judged on the basis of break history, pipe age and soil corrosiveness. Selected pipes ere installed between 1860 and Evaluation of the accuracy of the remaining thickness predicted by the new method was based on visual appearance and average wall thickness of exhumed samples as reported by Correng consulting services under contract with the City.

29 Case Studies Pipe Exhumed at Site 3 Installed in Cast Iron Echologics Measurements showed this pipe to be heavily deteriorated.

30 Case Studies Pipe Exhumed at Site 3

31 Case Studies Site 8 Pipe installed in Cast Iron Echologics measured the pipe to be in good condition

32 Pilot Study in Newark, NJ Condition Assessment performed on one section of 1890s era 6 Cast Iron Pipe Pipes in this area had been selected for relining A service leak was discovered during CA testing 3 coupon samples were extracted along the street for confirmation of results

33 Newark, New Jersey Fire Hydrant Service Leak at House #195 Average Pipe Wall Thickness of 0.18, 63.9% loss Pit #3 Pit #2 Pit #1 - Valve Confidential Use pursuant to Company 33

34 Case Studies

35 Newark, NJ Tuberculation and Graphitization does not contribute to the structural thickness This is the remaining structural thickness!

36 Las Vegas Valley Water Department Identified mains that did NOT need rehab or replacement Surveyed 10 miles of 16 to 36 bar-wrapped steel cylinder transmission main Discovered 2.5 miles still in great condition. Reduced budget by $2,000,000

37 Asbestos Cement Water Mains

38 Asbestos Cement Water Mains Lose Structural Stiffness rather than Pipe Wall Thickness Structural component of Pipe Matrix leaches out of the pipe wall leaving soft AC. Affected by: High water tables Aggressive water Stagnant water Aggressive Soil (Sulphates) Echologics Measures this Structural thickness

39 AC Pipe Background - Health Studies Several Major Studies Ambient Water Quality Criteria for Asbestos EPA (1980) Asbestos in the Water Supplies of the United States Millette et al (1983) Public Health Goal for Asbestos in Drinking Water CEPA (1983) Investigation of Cancer Incidence among the Woodstock, Asbestos Exposure Registry Population NY State Department of Public Health (2004) According to EPA evidence: drinking asbestos fibers can cause intestinal polyps Current EPA Limits: 7 million fibers/liter Most studies indicate that AC pipe degradation could be a significant water quality concern

40 Las Vegas Valley Water District 600 Miles of AC Pipe Originally Planned to replace all 600 miles Pilot: Two sections of 6 AC pipe tested 0.73 remaining structural thickness measured by Echologics Results indicated that pipe met requirements of PC200 Excavated pipe to confirm results Testing confirmed that results accurately represented the pipe s remaining structural thickness

41 Las Vegas Valley Water District: Velocity Measurement & Results Program Input Pipe Diameter (m) Output Wall thickness (mm) 18.5 Wall Thickness (in) 0.73

42 Las Vegas Valley Water District: Excavated Pipe

43 Southern Nevada Water Purveyor: 14 Pipe Degradation Project

44 Las Vegas Valley Water District: Asset Management Plan Utility has standardized non-invasive, non-destructive acoustical methods to test for AC pipe based on confidence and repeatability To date: ~30 miles of AC pipe tested successfully Most AC pipe was found to be in excellent condition Avoided unnecessary replacement Several areas of degraded AC pipe identified and replaced

45 Case Study: Medium-sized BC Utility Both hard and soft AC pipe; no discernable geographical/age patterns Several sections tested; identified one pipe as ~50% degraded Lab testing confirmed results Location Pipe Distance Nominal thickness Measured Structural Integrity Stiffness Loss 16 th to Spring 6 AC m mm 8.43 mm -50%

46 Ohio Projects

47 City of Dayton Small Project with AECOM. Surveyed 4,500 ft of a mid-sized CI water main that had experienced issues in the past. Ultrasonic measurements taken. Echologics Results aligned with Ultrasonic measurements.

48 Town of Dublin Curious to know what is happening within their system. Recently surveyed approx. 14,000 ft of Ductile Iron Water mains. Overall, Ductile Iron Pipe displayed moderate amounts of degradation. 2 leaks pin pointed, confirmed by Columbus Water.

49 City of Columbus Pilot Project w/ Malcolm Pirnie, Arcadis 10 sections of 1,000 ft Both Cast Iron and Ductile Iron of varying ages Soil Testing and Physical Samples taken at each site Echologics Results aligned with the physical samples on 9/10 sites.

50 Thickness Change (%) Thickness Comparision for City of Columbus Echologics Data Coupon Data Data Overlap 60% 40% 20% 0% -20% -40% -60% -80% Site No.

51 9 8 7 R² = CTL Pipe Rankings (1 is best) 4 3 Series1 Linear (Series1) Echologics Pipe Ranking (1 is best)

52 Summary

53 Summary Utilities need to understand condition of their water mains Condition assessment enables utilities to: Reduce costs Prioritize capital Maximize Service Life of existing water mains Utilities have options for condition assessment Non-invasive non-destructive condition assessment has distinct advantages

54 Summary: Benefits of Non-Invasive Non- Destructive Acoustic Condition Assessment Scalability Cover larger areas with one crew (~0.7 miles/day) Ease of use No need for specialized access, road repairs or service disruptions Top-down approach Large areas covered for lower costs than intrusive in-pipe technologies Screening performed on large areas to identify problems and avoid rehabbing or replacing pipes in good condition Prioritize capital spending Reduction of NRW Leak detection is performed On average, find 1 leak per mile of pipe surveyed Rehab costs of $50 - $200/foot vs. replacement costs of $150 - $300/foot Identifies mains NOT needing rehab or replacement

55 Condition Assessment Methods Advantages and Disadvantages of Acoustic Testing Advantages: Provides minimum structural wall integrity Non-destructive, Non-disruptive Cost effective Good survey accuracy Leak detection is performed at same time Can be included in engineering criticality models to prioritize pipes for replacement/rehab Disadvantages: Average wall thickness is obtained

56 Top Down Approach Review Historical Records Collect and review relevant records from the utility owner such as: Failure, repair history Leakage rate, pressure Develop large scale sampling program Perform Large Scale Screening Collect and analyze field data using non-intrusive methods: Soil chemistry Pipe locating Survey Level leak detection and Condition Assessment* Focus Efforts on Troubled Areas Correlate relevant records with field data and make informed decisions Use in-pipe (REFC, CCTV etc) technologies to determine failure mechanisms and plan for remedial action

57 Q & A For comments or additional information, please contact Geoff Boyd at , gboyd@echologics.com. Or, please visit