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

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It is anticipated that Insituform Technologies, Ltd., will seek the agreement of TW to sample this unique installation again in 2011. There is no data from the original installation which predates the formation of the Permaline Division of Edmund Nuttall, Ltd., (now Insituform Technologies, Ltd.), nor similar data from other installations. Today, TW is headquartered in Reading with operational centers based on major treatment plants at Mogden, Cross Ness, Sandford and Beckton. These operations centers use preferred contractors to undertake emergency works which investigate flooding incidents and other system failures, its crews identify lining needs which are passed to a lining manager based at Reading and sanctioned for implementation, mainly using the preferred contractor Onsite Central. Other specialist contractors such as Waterflow and Insituform can be used. Larger projects classed as capital works will be undertaken by any of four major framework contractors appointed for the current asset management period (AMP) 5. These contractors are B&V, Optimise, MGJV, or GBM and they are expected to utilize the preferred specialist subcontractors. Lining volumes are not centrally recorded, so it is difficult to estimate how much CIPP and other lining methods have been installed. TW and its antecedents, the city and municipalities of the region have been undertaking this type of work since before formation of TWA in 1973 and it is thought that lining volumes have fluctuated widely from 6 to 60 km/year. Policy changes in the four five-year AMPs since privatization have ensured that there has been no continuity of lining work. According to TW, the work currently undertaken is customer focused on solving problems and not asset focused. In England and Wales, according to the U.K. Water Regulator OFWAT, over this asset management period, the proportion of sewers in condition grade 3 to 5 (the poorest conditions) has increased from 20 to 30% of the network. According to OFWAT, TW has renovated 408 km (254 miles) and replaced 264 km (164 miles) of critical sewer since 1990-91. Critical sewers, in the U.K. perspective, are sewers identified for proactive maintenance. These may be located under major roads, highways, rail tracks or in other sensitive locations and serve critical facilities such as hospitals, major business or population centers where the consequences of failure are major. It is thought that critical sewers make up some 20% of the network. OFWAT has published data on renovation and replacement for non-critical sewers since 2000-01; nationwide annual rates of rehabilitation for non-critical sewers of 87 to 91 km (54 to 57 mi)/year are marginally lower than for critical sewers 83 to 110 km (52 to 68 mi)/year. It seems reasonable to assume that TW may have renovated about 800 to 900 km (500 to 560 mi) of all sewers, perhaps 45 km (28 mi) per year since 1990. Table C-2 summarizes sewer renovation data from TW and for all U.K. utilities. Table C-2. TW and U.K. Sewer Renovation Rates for 1990 to 2010 Asset Management Period Critical Sewers Renovated km Thames Water All U.K. Water Companies Non-Critical Sewers Renovated C-3 Critical Sewers Renovated km Non-Critical Sewers Renovated Water Mains Relined km AMP1 90-95 113 N/A 509 N/A 10,639 AMP2 95-00 36 N/A 711 N/A 9,670 AMP3 00-05 47.1 102 505.4 350.5 9,255 AMP4 05-10 231.7 118.8 1,162.5 1,356.7 6,238 Subtotal 427.8 >220.8 2,887.9 >1,707.2 35,802 Proposed AMP5 10-05 79.5 184 769.4 3,358.9 1,126
However, the figures published by OFWAT cannot be taken at face value in terms of total rehabilitation effort since they refer to rehabilitation activity in terms of structural enhancement. For example, a length of condition Grade 4 or 5 sewer lined to improve condition to Grade 3 or better is deemed a valid rehabilitation output and may be included in the volume of activity, whereas a joint sealing by CIPP in a Grade 1 or 2 sewer may improve serviceability, but not structure and accordingly will not be counted. The length reported may also refer to the whole section of sewer, whereas the repair may be a simple CIPP patch repair. So the volumes of work reported as undertaken by OFWAT may be at variance with actual lengths of lining installed by preferred contractors. The CIPP contractors themselves were contacted for estimates of work done for TW and, on this basis, from equally fragile data, it seems more likely that the actual volumes of CIPP undertaken for TW annually may be only about 25 to 30 km (16 to 19 mi) over the period since privatization. The bulk of TW’s experience since 1971 has been with polyester resin and felt lining, inverted with water and hot water cured. Currently, TW’s preferred lining methods include traditional polyester resin and felt for structural improvement, epoxy resin and felt for leak tight lining (mainly for pipes 150 mm in diameter), woven hose lining (Brawoliner) for small diameter pipes with multiple bends and UV cured glass reinforced polyester linings for critical locations such as adjacent to rail tracks where time pressures require rapid installations. TW confines its work to experienced contractors, particularly Onsite and Waterflow, having had unsatisfactory work completed by small contractors. In its experience, construction defects, if present, become apparent within 1 to 2 years of installation. Its experience overall has been good, though some deficiencies in older works have been identified through routine and emergency CCTV surveys where local municipalities acting as TW agents may not have been as informed on acceptance standards and where acceptance criteria have been improved over the years in the transition from WRc IGN 4.34.04 Issue 1 (April 1986) to the current BS12566 Part 4:2002 (see Table C-3). Table C-3. TW Sewer Renovation Acceptance Criteria and Relevant Standards WRc IGN 4-34-04 Criterion Issue 1 1986 Appearance Smooth, generally free from wrinkles, degree of wrinkles may be agreed by purchaser and manufacturer Thickness Minimum specified and up to 15% thicker. May be greater where felt Tensile Strength/ Modulus/ Elongation Flexural Strength/ Modulus/ Elongation layers overlap Not less than 25 MPa 1,700 MPa 1.5% Not less than 50 MPa 2, 600 MPa 1-2.5% WRc IGN 4.34.04 Issue 2 1995 Surface irregularities less than 6mm or tabulated value, % of diameter, normally longitudinal 2% in the invert and 5% above the flowline, circumferential 2% anywhere Minimum specified and up to 15% thicker C-4 BS EN 13566 Part 4:2002 Surface irregularities not more than 2% of diameter or 6 mm Mean thickness not less than design thickness and minimum not less than 80% of design thickness or 3 mm NA Not less than Declared value < 15 MPa N/A Not less than Declared value < 25 MPa Declared value Declared value < 0.75% Declared value < 0.5% Not less than Declared value < 25 MPa Declared value < 1,500 MPa Declared value < 0.75%
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EPA/600/R-12/004 | January 2012 | w
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DISCLAIMER The work reported in thi
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ACKNOWLEDGMENTS This report has bee
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samples had a flexural modulus valu
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CONTENTS DISCLAIMER ...............
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4.3.10.2 Upstream Sample ..........
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9.2.2 Recommendations for Developme
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Figure 5-27. Raman Spectra for the
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ABBREVIATIONS AND ACRONYMS AMP Asse
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1.0: INTRODUCTION This report forms
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1.2 Organization of the Report Foll
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Some sections of a sewer system may
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• The depth of the pipe below the
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Figure 2-3 highlights the main diff
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The most commonly used resins are i
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the glass fiber. The tube, which is
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3.0: DEVELOPMENT OF CIPP EVALUATION
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• The municipality would be willi
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• Measurements and/or physical sa
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Table 3-3. Laboratory Evaluation an
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4.1 Introduction 4.0: CITY OF DENVE
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Figure 4-1. Images of the Recovered
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Sample ID Figure 4-4. Soil Grain Si
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Location Table 4-5. Denver 8-in. Li
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Profile Plot Red - Steel tube Green
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Table 4-7. Results from Flexural Te
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35 Table 4-9. Comparison of Test Da
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4.2.12 Buckling Test. A steel mecha
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Figure 4-18. Pressure Gage and Pres
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4.2.13 Shore D Hardness. Durometer
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Figure 4-24. Barcol Hardness Readin
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increases and the heat of cure decr
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In summary, CCTV inspection of thre
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Figure 4-28. Thickness for Denver 4
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4.3.6.2 Downstream Sample. Seven sp
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Figure 4-34. Flexural Stress-Strain
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Table 4-18. Flexural Test Results f
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4.3.8.2 Upstream Sample. Specimens
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4.3.10 Barcol Hardness 4.3.10.1 Dow
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4.3.11.2 Downstream Sample. The Ram
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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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Page 115 and 116: age difference between the liners i
Page 117 and 118: Looking for correlations to the low
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Page 121 and 122: 7.0: RECOMMENDED TEST PROTOCOL FOR
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Page 125 and 126: Table 7-3. Overall Structure for a
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Page 131 and 132: 113 Table 8-9. Process Verification
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Page 169 and 170: STW uses CIPP for virtually all of
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