Retrospective Evaluation of Cured-in-Place Pipe - (NEPIS)(EPA ...

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does not include work on the behavior of internally pressurized liners for water main or force main renovation. Research on the appropriate external loadings to be designed for CIPP installations has also been carried out, including Spasojevic et al. (2004), Spasojevic et al. (2007), Law and Moore (2007), and Moore (2008). If the types or ratio of resins are an area of concern, QA/QC using nuclear magnetic resonance testing can be carried out to make this determination. Research on the properties of resins used for CIPP includes Kleweno (1994), Hayden (2004), and Bruzzone et al. (2008). 2.3.3 Environmental Issues. The principal issue rose about the environmental impacts of CIPP materials and their installation has been the release of styrene into the process water (or other water present in the host pipe) and into the air. This has been a significant issue in Europe encouraging changes in the way that CIPP is manufactured and supplied and the switch to UV-cured liners for smaller diameter CIPP rehabilitation. UV-cured liners (such as the German Brandenburger liner) use gas-tight membranes to minimize the release of styrenes during storage and installation and the UV-cure process does not require water or steam into which styrenes could leach before curing. Papers and reports discussing this issue in the U.S. include Lee (2008), Donaldson (2009), and Kampbell (2009). In most areas of the U.S., styrene-based CIPP resins with thermal curing are still in use, but closer attention to reducing gaseous styrene emissions and capturing water/condensate containing styrene is generally being practiced. The smaller quantities of liquid water present during steam curing means that water contamination is more easily handled in steam cures than in water cures (Kampbell, 2009). There is very little information concerning the environmentally-caused degradation of CIPP. Two references identified on this topic are Sever et al. (2005) and Potvin et al. (2008). In the evaluations of the oldest CIPP liners from the current study (see Sections 4 and 5), it was noted that the coating layer on the interior of the polyester resin was degraded or missing in the areas exposed to flow. This coating layer was used to isolate the polyester resin from the environment during impregnation, installation, and curing. Once cured, the layer had essentially served its purpose. Long-term exposure to water caused the polyurethane film used in early installations to breakdown due to hydrolysis, a process of slow but temperature-dependent dissolution. In newer liners, both improved formulations of polyether polyurethane (which has good resistance to hydrolysis) and PE are used as a coating material. The longevity of both coating materials is expected to be greatly improved over the original form of polyurethane coating. 14
3.0: DEVELOPMENT OF CIPP EVALUATION METHODOLOGY 3.1 Review of Potential Alternatives A variety of approaches to evaluate the state of deterioration of previously installed liners were considered in the initial stages of the project. Table 3-1 indicates the main alternatives considered and the advantages and disadvantages of each approach. Through a detailed literature search and the specific international scan effort described in Section 8, the research team was only able to find scattered efforts to thoroughly evaluate the long-term performance of rehabilitated sewer sections. Most typically, the rehabilitated sections were only evaluated using CCTV immediately following the installation and then perhaps periodically using CCTV depending on the overall inspection strategy of the agency. In some cases, this would mean a regular CCTV inspection at intervals of a number of years, while in other cases it may mean no follow up since the rehabilitated section would be moved to the lowest priority for inspection. Table 3-1. Potential Evaluation Strategies for Liner Deterioration Evaluation approach Advantages Disadvantages Targeted or periodic CCTV inspection Advanced scanning and nondestructive testing (NDT) methods Recovery of destructive samples from select locations • Relatively low cost • Familiar to agencies • Can uncover other operating problems such as potential blockages • Can provide broad coverage of relined sections within an agency leading to statistically meaningful results • More detail on such aspects as liner distortion, development of external voids, etc. • Physical samples of the liner are available for a variety of tests • Variation of material properties from as-installed requirements can be determined • Comparison with NDT methods possible to build future NDT evaluation procedures 15 • Can only identify deterioration or defects that are easily identified by CCTV inspection • No material properties obtained • Liner distortion difficult to identify • Not possible to evaluate intermediate stages of deterioration • More expensive than CCTV • Data that can be gathered still would not presently allow evaluation of intermediate stages of deterioration • Expense of retrieving physical samples limits the number of samples that can be recovered and hence the statistical validity of results in terms of system-wide performance • Expense can limit the wish of agencies to participate in a national evaluation program
Page 1 and 2: EPA/600/R-12/004 | January 2012 | w
Page 3 and 4: DISCLAIMER The work reported in thi
Page 5 and 6: ACKNOWLEDGMENTS This report has bee
Page 7 and 8: samples had a flexural modulus valu
Page 9 and 10: CONTENTS DISCLAIMER ...............
Page 11 and 12: 4.3.10.2 Upstream Sample ..........
Page 13 and 14: 9.2.2 Recommendations for Developme
Page 15 and 16: Figure 5-27. Raman Spectra for the
Page 17 and 18: ABBREVIATIONS AND ACRONYMS AMP Asse
Page 19 and 20: 1.0: INTRODUCTION This report forms
Page 21 and 22: 1.2 Organization of the Report Foll
Page 23 and 24: Some sections of a sewer system may
Page 25 and 26: • The depth of the pipe below the
Page 27 and 28: Figure 2-3 highlights the main diff
Page 29 and 30: The most commonly used resins are i
Page 31: the glass fiber. The tube, which is
Page 35 and 36: • The municipality would be willi
Page 37 and 38: • Measurements and/or physical sa
Page 39 and 40: Table 3-3. Laboratory Evaluation an
Page 41 and 42: 4.1 Introduction 4.0: CITY OF DENVE
Page 43 and 44: Figure 4-1. Images of the Recovered
Page 45 and 46: Sample ID Figure 4-4. Soil Grain Si
Page 47 and 48: Location Table 4-5. Denver 8-in. Li
Page 49 and 50: Profile Plot Red - Steel tube Green
Page 51 and 52: Table 4-7. Results from Flexural Te
Page 53 and 54: 35 Table 4-9. Comparison of Test Da
Page 55 and 56: 4.2.12 Buckling Test. A steel mecha
Page 57 and 58: Figure 4-18. Pressure Gage and Pres
Page 59 and 60: 4.2.13 Shore D Hardness. Durometer
Page 61 and 62: Figure 4-24. Barcol Hardness Readin
Page 63 and 64: increases and the heat of cure decr
Page 65 and 66: In summary, CCTV inspection of thre
Page 67 and 68: Figure 4-28. Thickness for Denver 4
Page 69 and 70: 4.3.6.2 Downstream Sample. Seven sp
Page 71 and 72: Figure 4-34. Flexural Stress-Strain
Page 73 and 74: Table 4-18. Flexural Test Results f
Page 75 and 76: 4.3.8.2 Upstream Sample. Specimens
Page 77 and 78: 4.3.10 Barcol Hardness 4.3.10.1 Dow
Page 79 and 80: 4.3.11.2 Downstream Sample. The Ram
Page 81 and 82: 5.1 Introduction 5.0: CITY OF COLUM
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April 16, 2010 The specimen was rec
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The resulting gradation curves are
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Table 5-4. Soil pH at Designated Lo
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Figure 5-8. Average Thickness at Di
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5.2.12 Flexural Testing. Specimens
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Figure 5-14. Flexural Stress-Strain
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Figure 5-16. Tensile Stress-Strain
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5.2.15 Buckling Test. A mechanical
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Figure 5-24. Localized Leak on the
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Figure 5-26. Barcol Hardness Readin
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5.3.3 Visual Inspection of Liner. I
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Figure 5-32. Ultrasonic Testing for
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Table 5-13. Geometric Data for Flex
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Figure 5-38. Shore D Hardness of Co
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6.1 Introduction 6.0: REVIEW AND CO
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Overall, the liners appear to be ho
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age difference between the liners i
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Looking for correlations to the low
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A significantly lower range of Shor
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7.0: RECOMMENDED TEST PROTOCOL FOR
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combining this broadly available in
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Table 7-3. Overall Structure for a
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Table 8-2. CIPP and Other Rehabilit
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Table 8-5. Rehabilitation Specifica
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113 Table 8-9. Process Verification
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Göttingen Stadtentwässerung: Göt
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experience and quality, and do not
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km of pipe and 50-year-old pipes ar
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methods are detailed in the Guide t
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The business of pipeline rehabilita
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• Destructive testing (but will n
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In Denver, in CCTV inspections of n
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9.2 Recommendations for Future Work
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Falter, B. 1996. “Structural Anal
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Lehmann, M.A, J.P. Schroeder and C.
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APPENDIX A LIST OF TEST STANDARDS R
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The following table lists the non-A
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B.1 Introduction This study was con
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Mean thickness values for each cont
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APPENDIX C INTERNATIONAL STUDY INTE
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The original Insituform liner insta
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However, the figures published by O
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exfiltration and infiltration. Any
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STW uses CIPP for virtually all of
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method. Top hat repairs to junction
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All design and construction supervi
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Process verification test samples a
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consultant born out of the corporat
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BW continues to use CIPP, mainly in
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East, but has not yet had marked su
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D-1
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D-3
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D-5
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D-7
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D-9
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D-11
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D-13
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D-15
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D-17
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D-19
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D-21
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D-23
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D-25
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D-27
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D-29
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