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42223177 Twin Falls ePulse Final Report - 2024
[ MUELLER ] NDITI A E ND LEAK D I N The City of Twin Falls, ID C IT O F IN FA.IjLs 4( S�Rvt��' Date: 8/9/2024 Client: City of Twin Falls, ID Utility: City of Twin Falls, ID Echo Project#: 42223177 Report Classification: Final For more information about us or to view our full line of water products,please visit www.echologics.com or call Echologirs customerservice at 1.800.423.1323. Mueller refers to one or more of Mueller Water Products,Inc.a Delaware corporation("MWP"),and its subsidiaries.MWP and each of its subsidiaries are legally separate and independent entities when providing products and services.MWP does not provide products or services to third parties.MWP and each of its subsidiaries are liable only for their own acts and omissions and not those of each other.MWP brands include Muellere,Echologicss,Hydro Gates,Hydro-Guard®,HYMAXs,Jones®,Krauszs,Mi.Nets,Milliken®,Pratte, Singers,and U.S.Pipe Valve&Hydrant. Please see muellerwp.com/brands and krauszusa.com to learn more. Copyright©2019 Echologics.All Rights Reserved.The trademarks,logos and service marks displayed in this document are the property of Mueller Water Products,Inc.,its affiliates or other third parties.Products marked with a section symbol(§)are subject to patents or patent applications.For details,visit www.mwppat.com.These products are intended for use in potable water applications.Please contact your Mueller Sales or Customer Service Representative concerning any other application(s). F 14064 3/19 Page 2 of 44 [This page left intentionally blank] ( M,UELLE -R] Page 3 of 44 EXECUTIVE SUMMARY Echologics, LLC (Echologics) provided acoustic condition assessment and leak detection services on critical segments of distribution water mains for the City of Twin Falls,Idaho(the City). Echologics surveyed 26,676 linear feet of cast iron pipe ranging in diameters from 4-inch through to 20-inch. Echologics' field personnel completed the survey in Twin Falls, ID from April 22nd,2024,to May 1st,2024. Echologics conducted the survey using the ePulse®method. This report presents the results of the ePulse®testing. Summary of key results Leak detection: • No leaks were discovered at the time of the survey. Condition Assessment: • 25 segments appear to be in poor condition with over 30%loss in original wall thickness. • 25 segments appear to be in moderate condition with between 10%to 30%loss in original wall thickness. • 3 segments appear to be in good condition with less than a 10%loss in original wall thickness. • 4 segments yielded no results. Recommendations: • For the water mains in moderate condition, the City may wish to consider installing permanent monitoring systems, depending on the consequence of failure, to allow immediate notification of pressure transients and/or leaks. The installation of permanent monitoring systems may help in preventing future failures. • Echologics recommends conducting follow-up field investigations on these mains in 5 years time, in order to measure the rate of decay and update the condition of the mains. • As Echologics has only assessed a small percentage of the City's water distribution and transmission pipe network,the City may wish to consider testing more of the network. This will allow the City to identify and extend the service life of pipes reported in good condition,and allow for better prioritization of their pipe replacement program and capital budget expenditures. The City may also consider pipe rehabilitation as an option to reduce costs associated with water main replacement.Utilizing"evidence based"condition assessment data,as highlighted in this report,can be a good proactive approach to asset management that is both cost-effective and non-disruptive. ( MUELLER) Page 4 of 44 TABLE OF CONTENTS ExecutiveSummary.........................................................................................................................................................................3 1. PROJECT BACKGROUND.......................................................................................................................................................5 2. RESULTS...............................................................................................................................................................................8 2.1 Leak Detection...............................................................................................................................................................................8 2.2 ePulse®Condition Assessment....................................................................................................................................................8 2.2.1 Discussion of Results............................................................................................................................................12 2.2.2 Segments with No Results....................................................................................................................................12 2.2.3 Greater Wall Thickness Than Expected................................................................................................................14 3. CONCLUSIONS AND RECOMMENDATIONS.........................................................................................................................15 3.1 Conclusions.................................................................................................................................................................................15 3.2 Recommendations and Next Steps............................................................................................................................................15 4.DISCLAIMER...............................................................................................................................................................................18 APPENDIX A DETAILED RESULTS....................................................................................................................................................19 A.1 Site Details...................................................................................................................................................................................19 A.2 Leak Detection Results...............................................................................................................................................................19 A.3 Pipe Property Details...................................................................................................................................................................20 A.4 ePulsev Condition Assessment Results.....................................................................................................................................22 A.4.1 Third Ave North ...................................................................................................................................................22 A.4.2 Fourth Ave West..................................................................................................................................................23 A.4.3 Eldridge Ave.........................................................................................................................................................24 A.4.4 Blue Lakes Blvd North..........................................................................................................................................25 A.4.5 Locust St South ....................................................................................................................................................28 A.4.6 Main Ave East......................................................................................................................................................29 A.4.7 Ash St...................................................................................................................................................................30 A.4.8 Stadium Blvd........................................................................................................................................................31 A.4.9 Filler Ave West.....................................................................................................................................................32 APPENDIX B INTERPRETATION OF RESULTS..................................................................................................................................34 B.1 Echowaveg Leak Detection.........................................................................................................................................................34 B.2 ePulsev Condition Assessment..................................................................................................................................................35 B.3 Limitations...................................................................................................................................................................................39 B.4 Sensitivity Analyses and Considerations....................................................................................................................................40 APPENDIX C DETAILED METHODOLOGY.........................................................................................................................................41 C.1 Leak Detection.............................................................................................................................................................................41 C.2 ePulse®Mean Hoop Thickness Testing.....................................................................................................................................42 APPENDIXD ABBREVIATIONS.........................................................................................................................................................43 APPENDIX E GLOSSARY OF TECHNICAL TERMS.............................................................................................................................44 ( MUELLER) Page 5 of 44 1. PROJECT BACKGROUND The City of Twin Falls, Idaho (the City) contracted Echologics as a part of their pipe replacement program (PRP),to assess pipe conditions on critical segments of the City's metallic water mains.Primary objectives of the PRP include: • Determine the condition of the tested metallic pipe • Investigate the system for the existence of any leaks • Utilize pipe condition information to assist with rehabilitation or replacement decisions by the City To help the City achieve these objectives, Echologics utilized its patented ePulse®technology to determine the current condition of the pipes in scope. In addition to condition assessment, leak detection was also performed. This report provides detailed information on how Echologics can support the City in ensuring these objectives have been met. The project included 26,676 linear feet of distribution mains located in the City of Twin Falls,as illustrated below in Figure 1. ECHOLOW Twin Falls ePulse Overview Blue ice•.Bnw North _ U_».. Her AM w«t ••,.r. Y w � A Third Art NO I ouirth Av.Vllwt St 'Mum Ave EMt St South �►-sae► v , - Eldredge Ave O Notes ru••++a.W.r..•Yywe nw• Panotro0UM•airMA Figure 1:System Overview and Site Locations ( MUELLER) Page 6 of 44 Table 1 below shows the pipe material and installation years for each site surveyed. Table 1 Sites Surveyed Site Distance Pipe Material Pipe Diameter Install Year Segment Number Tested(ft) (in) 231771A001, Third Ave North 1,877 Cast Iron (CAS) 6 1940-46 231771A002, 231771A003, 231771AO04 231771A005, Fourth Ave 1,753 Cast Iron (CAS) 6 1940-46 231771A006, West 231771A007, 231771AO08 231771A009, 231771A010, Cast Iron (CAS) 231771A011, Eldridge Ave 3,927 8 1940-46 231771A012, 231771A013, 231771A014, 231771AO15 231771A019, 6 1940-46 231771A020, 231771A021, 231771AO22 231771A023, Blue Lakes Blvd 4 Cast Iron (CAS) 8 1940-46 231771A025, North ,264 231771A026, 231771AO27 12 1962-65 231771AO24 231771A016, 20 1962-65 231771A017, 231771AO18 4 1940-46 231771A030, Locust St South 2,541 Cast Iron (CAS) 231771AO40 12 1962-65 231771A028, 231771AO29 231771A032, Main Ave East 1,927 Cast Iron (CAS) 8 1940-46 231771A033, 231771A034, 231771AO35 231771A036, Ash St 1,973 Cast Iron (CAS) 4 1940-46 231771A037, 231771A038, 231771AO39 4 1940-46 231771A044, 231771AO45 231771A046, Stadium Blvd 3,104 Cast Iron (CAS) 6 1940 46 231771AO47 231771A041, 8 1940-46 231771A042, 231771AO43 231771A048, 231771A049, 6 1940-46 231771A050, Filler Ave West 5310 Cast Iron (CAS) 231771A051, 231771AO52 10 1940-46 231771AO53 231771AO54: ( MUELLER) Page 7 of 44 Site Distance Pipe Material Pipe Diameter Install Year Segment Number Tested(ft) (in) 231771A055, 231771A056, 231771A057, 231771AO58 Field tests began on April 22nd, 2024, and required eight days to complete with a team of two members.Traffic Control support was provided bythe City of Twin Falls.Additionally,in areas without acceptable sensor connection points,the City installed potholes. For this project, potholes were small diameter vacuum excavations exposing the crown of the pipe. This allowed Echologics to magnetically connect sensors directly to the pipe wall. ePulse® condition assessment combines acoustic data measured in the field with information about a pipe's construction to calculate its current average remaining wall thickness.The pipe's material,internal diameter,and modulus of elasticity are critical variables in this calculation.ePulse®condition assessment calculates the percentage of average thickness loss by comparison of the measured thickness to the design thickness of the pipe. Echologics used the pipe properties shown in Table 2, based on install dates and pipe classes provided by Twin Falls during the first year of the project.Information on nominal pipe specifications for Class D cast iron pipes,were taken from C100-1908:AWWA Standard Specifications or Cast Iron Water Pipes And Special Castings. It is not anticipated that any pipes in this project scope include cement mortar lining. Table 2 Pipe Properties Pipe Material Thickness Internal Nominal Thickness Class Diameter (in) (in) Cast Iron D 4 0.52 Cast Iron D 6 0.55 Cast Iron D 8 0.60 Cast Iron D 10 0.68 Cast Iron D 12 0.75 Cast Iron D 14 0.82 Cast Iron D 16 0.89 Cast Iron D 20 1.03 ( MUELLER) Page 8 of 44 2. RESULTS 2.1 LEAK DETECTION No leaks or points of interest were detected during the time of the survey. 2.2 EPULSE®CONDITION ASSESSMENT The ePulse®method measures the average remaining wall thickness of a segment of pipe.The technology combines acoustic data measured in the field with information about a pipe's manufacturing to calculate its current hoop thickness.The pipe's material, internal diameter,and modulus of elasticity are all critical variables in this calculation.The percentage of average wall thickness loss is calculated by comparing the measured thickness to the design thickness.The results are also presented as a qualitative category indicating the expected condition of the main.Table 4 shows these qualitative condition categories.Results marked"NR" indicate that no result was attainable on a pipe segment. Table 3:Qualitative Categories and Color Coding Change in Hoop Description Color Code Thickness Less than 10% Good Green 10%to 30% Moderate Yellow Greater than 30% Poor The ePulse®condition assessment results are presented in Table 5 below. ( MUELLER) Page 9 of 44 Table 4:ePulse®Pipe Condition Assessment Results Sensor Segment Pipe Internal Nominal Remaining a Sensor 1 /o Change Segment Street Name 2 Length Diamete Thickness Thickness Location Location (ft) Material r(in) (in) (in) from Nominal 231771AO01 Third Ave North 3478 3477 476 CAS 6 0.55 0.36 231771AO02 Third Ave North 3470 3477 419 CAS 6 0.55 0.37 231771AO03 Third Ave North 3470 3469 456 CAS 6 0.55 0.41 -25 231771AO04 Third Ave North 3613 3469 526 CAS 6 0.55 0.33 231771AO05 Fourth Ave West 3446 3437 356 CAS 6 0.55 0.32 231771AO06 Fourth Ave West 3434 3437 527 CAS 6 0.55 NR 231771AO07 Fourth Ave West 3434 Echo-2 412 CAS 6 0.55 0.25 231771AO08 Fourth Ave West 3424 Echo-2 458 CAS 6 0.55 0.54 2 231771AO09 Eldridge Ave 48966 14796 683 CAS 8 0.60 0.52 -13 231771AO10 Eldridge Ave 48969 14796 636 CAS 8 0.60 0.42 -30 231771A011 Eldridge Ave 48969 102-34 553 CAS 8 0.60 0.52 -13 231771AO12 Eldridge Ave 39251 102-34 461 CAS 8 0.60 0.43 -28 231771AO13 Eldridge Ave 39251 16436 527 CAS 8 0.60 0.45 -25 231771AO14 Eldridge Ave 30826 16436 616 CAS 8 0.60 0.57 -5 231771AO15 Eldridge Ave 30826 10546 451 CAS 8 0.60 0.44 -27 231771AO16 Blue vakrteh Blvd 48316 191-2 488 CAS 20 1.03 0.67 -35 231771AO17 Blue Lakes Blvd PH-199-1 191-2 264 CAS 20 1.03 0.68 -34 231771AO18 Blue Lakes Blvd PH-199-1 29973 704 CAS 20 1.03 0.68 34 North 231771AO19 Blue Lakes Blvd 48722 48327 326 CAS 6 0.55 0.30 North 231771AO20 Blue Lakes Blvd 48329 48327 310 CAS 6 0.55 0.35 North MUELLER( ) Page 10 of 44 Sensor Segment Internal Nominal Remaining o Segment Street Name Sensor 1 2 Length Pipe Diamete Thickness Thickness �Change Location Location Material from Nominal (ft) r(in) (in) (in) 231771AO21 Blue Lakes Blvd 48329 49-581 545 CAS 6 0.55 0.36 North 231771AO22 Blue Lakes Blvd PH-3002- 49-581 237 CAS 6 0.55 0.43 -22 North 1 231771AO23 Blue Lakes Blvd 29977 48281 119 CAS 8 0.60 0.19 North 231771AO24 Blue Lakes Blvd PH-3084- 48281 184 CAS 12 0.75 0.30 North 1 231771AO25 Blue Lakes Blvd PH-3084- Echo-1 398 CAS 8 0.60 0.48 -20 North 1 231771AO26 Blue Lakes Blvd 48690 Echo-1 280 CAS 8 0.60 0.50 -17 North 231771AO27 Blue Lakes Blvd 48690 Echo-5 409 CAS 8 0.60 0.37 North 231771AO28 Locust St South 48966 1098 1 616 CAS 12 0.75 0.59 -21 231771AO29 Locust St South 48965 1098 1 670 CAS 12 0.75 0.54 -28 231771AO30 Locust St South 48696 48282 629 CAS 4 0.52 NR 231771AO32 Main Ave East 87-771 48975 539 CAS 8 0.60 NR 231771AO33 Main Ave East 48976 48975 457 CAS 8 0.60 0.29 231771AO34 Main Ave East 48976 48700 488 CAS 8 0.60 0.61 2 231771AO35 Main Ave East 46072 48699 443 CAS 8 0.60 0.47 -22 231771AO36 Ash St 27167 48972 570 CAS 4 0.52 0.34 -35 231771AO37 Ash St PH-9i 83 48972 487 CAS 4 0.52 0.38 -27 231771AO38 Ash St PH-9i 83 88-783 445 CAS 4 0.52 0.25 52 231771AO39 Ash St 48971 88-783 471 CAS 4 0.52 0.25 231771AO40 Locust St South PH-897-1 48282 626 CAS 4 0.52 0.40 -23 231771AO41 Stadium Blvd 2338 2018 1 408 CAS 8 0.60 0.41 MUELLER( ) Page 11 of 44 Sensor Segment Internal Nominal Remaining o Segment Street Name Sensor n 2 Length Pipe Diamete Thickness Thickness ��Change Location Location Material from Nominal (ft) r(in) (in) (in) 231771AO42 Stadium Blvd 62-262 2018 1 430 CAS 8 0.60 0.43 -28 231771AO43 Stadium Blvd 62-262 47107 585 CAS 8 0.60 0.46 -23 231771AO44 Stadium Blvd 47919 47107 190 CAS 4 0.52 0.20 231771AO45 Stadium Blvd 47919 8861 616 CAS 4 0.52 0.26 231771AO46 Stadium Blvd 8859 8861 370 CAS 6 0.55 0.47 -15 231771AO47 Stadium Blvd 8859 9156 505 CAS 6 0.55 0.48 -13 231771AO48 Filler Ave West 48979 59-80 720 CAS 6 0.55 0.34 -38 231771AO49 Filler Ave West 48994 59-80 738 CAS 6 0.55 0.26 -53 231771AO50 Filler Ave West 48994 Echo-6 309 CAS 6 0.55 0.34 -38 231771AO51 Filler Ave West 48293 Echo-6 533 CAS 6 0.55 0.35 231771AO52 Filler Ave West 48293 48296 352 CAS 6 0.55 0.43 -22 231771AO53 Filler Ave West 48709 3274 384 CAS 10 0.68 NR 231771AO54 Filler Ave West 48709 48997 507 CAS 10 0.68 0.56 -18 231771AO55 Filler Ave West 48298 48997 424 CAS 10 0.68 0.58 -15 231771AO56 Filler Ave West 48298 48707 466 CAS 10 0.68 0.53 -22 231771AO57 Filler Ave West Echo-8 48707 280 CAS 10 0.68 0.53 -22 231771AO58 Filler Ave West Echo-8 48295 597 CAS 10 0.68 0.54 -21 *Access Points noted with the Echo prefix are appurtenances without available details on provided GIS, updates to Twin Falls asset numbers may be added with further GIS information. **Access Points noted with the PH prefix are potholes installed by Twin Falls for access directly to the water main ( MUELLE -R] Page 12 of 44 2.2.1 DISCUSSION OF RESULTS ePulse Condition Assessment Results Breakdown Ll F 44% ■Good Moderate ■ Poor ■ No Result Figure 2:ePulse Results Breakdown The results presented in Table 5 and Figure 2 show that 3 out of 57 segments tested(5%of total number of segments)appear to be in good condition with less than 10% loss in wall thickness. Echologics identified 25 segments (44% of total number of segments)to be in moderate condition with wall thickness loss of 10%to 30%from nominal. Echologics identified 25 segments (44%of total number of segments)appear to be in poor condition with more than 30%loss in wall thickness.Echologics could not provide a result for the remaining 4 segments. Echologics measured the presented distances on site.The following methods are used to achieve a reliable distance measurement: 1. The distance is measured multiple times with a measuring wheel 2. The distance is cross-checked with available information from GIS maps Distance accuracy is important for ePulse results and in general, a 1%error in distance measurement can result in a more than 2%error in final percentage of wall thickness lost.A discussion of the effect of distance error on the results as well as a closer look at other possible sources of error and their effect on the results can be seen in Appendix A. Detailed discussion on the results for each site and group of segments are presented in the Appendix A. 2.2.2 SEGMENTS WITH NO RESULTS Segments 231771A006,231771A030,231771A032 and 231771A053 were marked as no result("NR").These were marked as no result("NR")due to possible factors attributing to poor sound propagation or unrealistic results.These factors may include: 1. Inaccurate pipe material or specification. 2. Inadequate distance for accurate recording of time delay. 3. Inaccurate pipe configuration as per GIS layout Each segment is discussed in more detail below: • Segment 231771A006:While Echologics was able to collect acoustic data for this segment,the speed of sound result was well outside of the range typically seen for this material and diameter.This is likely due to the pipe geometry leading ( MUELLER) Page 13 of 44 to an inaccurate distance measurement.Observations onsite indicate the pipe layout differs significantly from the layout presented on the provided GIS maps. While the GIS maps show the hydrant lateral connecting northwest of the water main line valve, onsite the hydrant lateral appears to connect southeast of the valve.This assumption is supported by the location of the hydrant isolation valve and the position of the hydrant. Echologics recommends the City locate the water main and hydrant lateral to determine the distance between the tee connection and the water main line valve. Once complete,Echologics will review the analysis again to determine if a result can be provided.Leak detection was still possible for this segment. • Segment 231771AO30: A result could not be provided due to poor sound propagation within this segment. While Echologics was able to propagate sound between the two sensors,the resulting signal was low quality and inadequate for a condition assessment measurement.This is likely due to either a poor sensor connection or the presence of PVC repairs within this segment. Leak detection was still possible for this segment. • Segment 231771AO32:A result could not be provided for this segment due to poor sound propagation. Based on the poor-quality signal and low frequencies observed, Echologics believes there is likely PVC within this segment.While leak detection was possible for this segment,leak detection sensitivity was likely reduced. • Segment 231771AO53:A result could not be provided for this segment due to poor sound propagation.While Echologics was able to propagate sound between the two sensors,the resulting signal was low quality and inadequate for a condition assessment measurement.The poor signal appears to be caused by a poor sensor connection.Poor sensor connections are typically caused by significant dirt or debris in the valve box or a poor connection between the valve riser/rod and the valve nut. ( MUELLER) Page 14 of 44 2.2.3 GREATER WALL THICKNESS THAN EXPECTED In some instances, Echologics observed acoustic wave velocities along a segment which resulted in a measured wall thickness slightly greater than the assumed nominal thickness.This can occur due to the following primary reasons: 1. Manufacturing tolerances or unaccounted for lining 2. Incorrect assumptions of pipe specifications 3. Incorrect distance measurements due to unknown pipe configuration. Echologics has identified one segment, Segment 231771A034, that shows a measured thickness slightly greater (within 0.01 inches)than the nominal thickness.This is within typical manufacturing tolerances and/or margin of error for ePulse.This segment is expected to be in very good condition. If further information becomes available on this main,please contact Echologics so that updates can be made to the report. ( MUELLER) Page 15 of 44 3. CONCLUSIONS AND RECOMMENDATIONS 3.1 CONCLUSIONS Echologics has successfully assessed pipe wall condition and leak detection of 24,597 feet of distribution water mains in Twin Falls, Idaho. Condition assessment results could not be provided on 2,079 feet of the total distance being assessed but leak detection was still possible.The main conclusions for this project are as follows: A. The ePulse®testing method can be easily implemented within the City's water distribution network without the need for traditional excavations,external traffic control or substantial support from Twin Falls water operators. Field-testing was completed without any interruption to service or disruptions to the City's customers. B. The ePulse®acoustic field-testing obtained results for 93%of the segments tested. Four segments tested returned "No Result(NR)". It is recommended that Twin Falls review the class and materials for all pipes tested to ensure the correct nominal thickness. If a change to the nominal thickness is required, Echologics can re-calculate the results with the updated pipe specifications. C. For Segment 231771A006,Echologics recommends the City locate the water main and hydrant lateral to determine the distance between the tee connection and the water main line valve.Once complete, Echologics will review the analysis again to determine if a result can be provided. D. The ePulse®testing was able to isolate 10,995 feet of degraded pipe with high (greater than 30%)wall thickness loss. Echologics strongly recommends the City review and compare the inputs used by Echologics to the original lay schedule and pipe specification information.Significant changes to the material or diameters presented in this report will affect Echologics' ePulse measured thickness.that Twin Falls review the material specifications of these pipes to confirm the high levels of degradation.Additionally,if the assumed nominal thickness is incorrect,the percent degradation value will also change. 3.2 RECOMMENDATIONS AND NEXT STEPS Based on the results of the condition assessment and leak detection survey for this project, Echologics offers the following overall program recommendations and next steps: • For the water mains in moderate condition, the City may wish to consider installing permanent monitoring systems, depending on the consequence of failure, to allow immediate notification of pressure transients and/or leaks. The installation of permanent monitoring systems may help in preventing future failures. • Echologics recommends conducting field investigations on these mains in 5 years time, in order to measure the rate of decay and update the condition of the mains. • As Echologics has only assessed a small percentage of the City's water distribution and transmission pipe network,the City may wish to consider testing more of the network.This will allow the City to identify and extend the service life of pipes reported in good condition,and allow for better prioritization of their pipe replacement program and capital budget expenditures. The City may also consider pipe rehabilitation as an option to reduce costs associated with water main replacement.Utilizing"evidence based"condition assessment data,as highlighted in this report,can be a good proactive approach to asset management that is both cost-effective and non-disruptive. It is important to note that structural pipe condition is one of many factors in evaluating a pipe's suitability for service but should not be the only consideration used in replacement and deferral decisions.Other important factors that should be considered may include pipe-loading conditions, hydraulic capacity of the pipe, road repair/renewal schedules, consequence of pipe failure, customer complaints, rate of decay etc. When interpreting ePulse®results,asset owners should understand the following: 1. Leaks can still occur on water mains with good pipe wall condition for reasons other than pipe wall degradation, such as pressure transients,leaks atjoints,leaks on service connections,winter weather(freeze/thaw),poor installation, etc. 2. If a leak is detected on these segments, a repair should be sufficient for remediation, because the majority of the remaining pipe wall is in good structural condition. 3. The need for future assessment of these pipes should take into account the consequence of failure. Depending on the consequence of failure, it may be beneficial to equip these pipelines with a continuously monitoring leak detection system. For example,a non-redundant main servicing a hospital may benefit from immediate detection of leaks as soon as they develop. With this in mind,we further recommend the following actions for the three condition categories. ( MUELLER) Page 16 of 44 Good Condition Pipe- DEFER/LOW PRIORITY If the condition assessment results classify the mains as"Good Condition",they are in good structural condition and do not need attention in the near future, (unless they are under higher-than-normal loading conditions). The pipes in this category have a remaining wall thickness within 10%of the nominal wall thickness. Recommendations for good condition pipe are as follows: 1. We suggest the City continue with their standard maintenance programs for these mains. 2. Common industry practice for good condition pipe is to follow-up with condition assessment testing in approximately 10 years, depending on the consequence of failure. This allows for measurement of the rate of change of condition with time. If these mains require rehabilitation for other reasons such as low pressure or poor water quality complaints,then cleaning and lining may be an option to consider. 3. Employing the use and benefits of cathodic protection to slow or even stop the"aging" process of external corrosion. Moderate Condition Pipe- MONITOR/MEDIUM PRIORITY If the condition assessment results classify the mains as"Moderate Condition",the pipes may be medium priority and should be monitored depending on pipe loading conditions.It is important to note that pipes in this category may show a reduced capacity to withstand loading conditions,especially on pipes that are approaching 30%loss in wall thickness. Depending on the criticality of the main,we recommend monitoring these pipes.The following are some of the possible mitigation methods: 1. For mains without an internal lining,cleaning and lining can often extend the life of moderate condition mains,as well as adding cathodic protection. 2. Regularly scheduled traditional leak detection surveys.These are a relatively inexpensive option capable of finding many leaks within a system. However,this method can be fairly labor intensive and may not prevent catastrophic failures on high consequence pipelines. 3. A permanent leak monitoring system that is capable of finding most leaks on a pipeline,including small leaks before they turn into catastrophic failures. 4. A follow-up condition assessment survey to measure the rate of decay and update the condition of the mains.A common practice for moderate condition pipe is to reassess these mains in 5 years,depending on the consequence of failure.An analysis of the results can be used to determine the decay rates for these mains.The established decay rate may have an impact on the remaining service life of the mains. Measuring this can allow for improved asset management. ( MUELLER) Page 17 of 44 Poor Condition Pipe-ADDRESS/HIGH PRIORITY If the condition assessment results classify the mains as "Poor Condition",the pipes are likely in need of immediate attention. Depending on pipe loading condition,these pipes are at higher risk of experiencing leaks and catastrophic failures,and theyshould be addressed as soon as possible. In most cases, pipe segments that fall within this category have reached,or are approaching,the end of their useful life. Actions such as structural lining,slip-lining,and/or full replacement should be investigated as a likely immediate requirement. Such actions as continuous leak monitoring,cathodic protection and/or cleaning and lining will most likely not offer tremendous value or extend the life of the water main in a cost-effective manner. Additional Considerations Each water network will have its own dominant degradation mechanism,as well as unique local considerations.We recommend that the City use the results presented in this report in combination with other data and information available from additional services.This additional asset information may include: • Soil Corrosivity.If corrosive soils are discovered and the main is in poor condition,the degradation is likely related to soil conditions. • Water Aggressiveness.Aggressive water would suggest that some of the degradation is caused from the inside,and this can be assumed to cause similar degradation rates for similar types of main. • Break History.Correlating condition assessment results with break history can help identify sections of main that are at increased risk of failure.These factors are not necessarily related,as it is possible for pipes to have high break rates for reasons other than pipe wall degradation. • Consequence of Failure. Combining condition assessment results with consequence of failure analysis is used to generate a risk assessment. Comparing the ePulse condition assessment results with these additional considerations will allow the City to direct their rehabilitation efforts in a cost-effective manner,by creating a high-level rehabilitation picture takes all sources of degradation into consideration. ( MUELLE -R] Page 18 of 44 4. DISCLAIMER All forms of non-destructive testing involve an inherent level of uncertainty.Such testing is dependent on input parameters, and outputs can be significantly affected by variation from assumed parameters. This report includes certain suggestions and recommendations made by us which are based on,among others,(i)the findings included in the report,(ii)its experience and(iii) an understanding of the client's particular requirements.We acknowledge that the client may use this report to consider potential opportunities for pipeline repairs/replacement/rehabilitation; however,we disclaim any liability that may arise in connection with decisions based on these suggestions or recommendations or their implementation. ( MUELLER) Page 19 of 44 APPENDIXA DETAILED RESULTS This section provides a detailed presentation of the project scope,data collected,and results obtained during the project. A.1 SITE DETAILS This project was divided into three distinct work sites.An overview map of the sites is shown in Figure A.1-1:System Overview and Site Locations below,followed by detailed information on each of the sites. FE CHOLOGICS Twin Falls ePulse Overview h Blue Lakes BW North Legend 3 Use.N.L. Eller Ave VYest � S.9".ts Y,. ird Ave North Fourth Are Ylfest St Mein Ave East t JA. a. i Lca�st St South Ap.i"tT Eldredge Are t. Notes o is tOlt TNa"v0 a a uw gvwsm csc apt taw r Inrnst�q Nw w 4>, .0—ory Ow W'—".M..m►.a iw+0 wW a"W'na d ammo riG1 .1 961_MMO_Mtwatar�4.+urY-SOt+� a arrrr�tr.� C L=,&GoWAOWS Gr Q Ud THIS V P IS NOT TO K USED id NAMATION i Figure A.1-1:System Overview and Site Locations A.2 LEAK DETECTION RESULTS No leaks or points of interest were detected during the time of the survey. ( MUELLER) Page 20 of 44 A.3 PIPE PROPERTY DETAILS The pipe properties used in this project are presented in Table A.3-1,which were obtained from the client through a GIs request. Nominal thicknesses were determined from pipe standards details in section 1. Table A.3-1:Pipe Properties Segment ID Street Name Install Pipe Diameter Nominal Year Material (in) Thickness(in) 231771A001 Third Ave North 1940-46 CAS 6 0.55 231771A002 Third Ave North 1940-46 CAS 6 0.55 231771A003 Third Ave North 1940-46 CAS 6 0.55 231771A004 Third Ave North 1940-46 CAS 6 0.55 231771A005 Fourth Ave West 1940-46 CAS 6 0.55 231771A006 Fourth Ave West 1940-46 CAS 6 0.55 231771A007 Fourth Ave West 1940-46 CAS 6 0.55 231771A008 Fourth Ave West 1940-46 CAS 6 0.55 231771A009 Eldridge Ave 1940-46 CAS 8 0.60 231771A010 Eldridge Ave 1940-46 CAS 8 0.60 231771A0ll Eldridge Ave 1940-46 CAS 8 0.60 231771A012 Eldridge Ave 1940-46 CAS 8 0.60 231771A013 Eldridge Ave 1940-46 CAS 8 0.60 231771A014 Eldridge Ave 1940-46 CAS 8 0.60 231771A015 Eldridge Ave 1940-46 CAS 8 0.60 231771A016 Blue Lakes Blvd North 1962-65 CAS 20 1.03 231771A017 Blue Lakes Blvd North 1962-65 CAS 20 1.03 231771A018 Blue Lakes Blvd North 1962-65 CAS 20 1.03 231771A019 Blue Lakes Blvd North 1940-46 CAS 6 0.55 231771A020 Blue Lakes Blvd North 1940-46 CAS 6 0.55 231771A021 Blue Lakes Blvd North 1940-46 CAS 6 0.55 231771A022 Blue Lakes Blvd North 1940-46 CAS 6 0.55 231771A023 Blue Lakes Blvd North 1940-46 CAS 8 0.60 231771A024 Blue Lakes Blvd North 1962-65 CAS 12 0.75 231771A025 Blue Lakes Blvd North 1940-46 CAS 8 0.60 231771A026 Blue Lakes Blvd North 1940-46 CAS 8 0.60 231771A027 Blue Lakes Blvd North 1940-46 CAS 8 0.60 231771A028 Locust St South 1962-65 CAS 12 0.75 231771A029 Locust St South 1962-65 CAS 12 0.75 231771A030 Locust St South 1940-46 CAS 4 0.52 231771A032 Main Ave East 1940-46 CAS 8 0.60 231771A033 Main Ave East 1940-46 CAS 8 0.60 231771A034 Main Ave East 1940-46 CAS 8 0.60 231771A035 Main Ave East 1940-46 CAS 8 0.60 ( MUELLER) Page 21 of 44 231771AO36 Ash St 1940-46 CAS 4 0.52 231771AO37 Ash St 1940-46 CAS 4 0.52 231771AO38 Ash St 1940-46 CAS 4 0.52 231771AO39 Ash St 1940-46 CAS 4 0.52 231771AO40 Locust St South 1940-46 CAS 4 0.52 231771AO41 Stadium Blvd 1940-46 CAS 8 0.60 231771AO42 Stadium Blvd 1940-46 CAS 8 0.60 231771AO43 Stadium Blvd 1940-46 CAS 8 0.60 231771AO44 Stadium Blvd 1940-46 CAS 4 0.52 231771AO45 Stadium Blvd 1940-46 CAS 4 0.52 231771AO46 Stadium Blvd 1940-46 CAS 6 0.55 231771AO47 Stadium Blvd 1940-46 CAS 6 0.55 231771AO48 Filler Ave West 1940-46 CAS 6 0.55 231771AO49 Filler Ave West 1940-46 CAS 6 0.55 231771AO50 Filler Ave West 1940-46 CAS 6 0.55 231771AO51 Filler Ave West 1940-46 CAS 6 0.55 231771AO52 Filler Ave West 1940-46 CAS 6 0.55 231771AO53 Filler Ave West 1940-46 CAS 10 0.68 231771AO54 Filler Ave West 1940-46 CAS 10 0.68 231771AO55 Filler Ave West 1940-46 CAS 10 0.68 231771AO56 Filler Ave West 1940-46 CAS 10 0.68 231771AO57 Filler Ave West 1940-46 CAS 10 0.68 231771AO58 Filler Ave West 1940-46 CAS 10 0.68 ( MUELLER) Page 22 of 44 A.4 EPULSE®CONDITION ASSESSMENT RESULTS A.4.1 THIRD AVE NORTH Mi sd� �3� a Figure A.4.1-1:Third Ave North a9P P 9h9 ory ch �C �9� 4 h zr c>�e �9�Po \us awn rntij � Figure A.4.2-2:Third Ave North ( MUELLE -R] Page 23 of 44 Table A.4.1-1:Third Ave North ePulse®Condition Assessment Details Segment Internal Nominal Remaining °�0 Sensor 1 Sensor 2 Pipe Change Segment Street Name Length Diameter Thickness Thickness Location Location (ft) Material (in) (in) (in) from Nominal 231771AO01 Third Ave North 3478 3477 476 CAS 6 0.55 0.36 231771AO02 Third Ave North 3470 3477 419 CAS 6 0.55 0.37 231771AO03 Third Ave North 3470 3469 456 CAS 6 0.55 0.41 -25 231771AO04 Third Ave North 3613 3469 526 CAS 6 0.55 0.33 A.4.2 FOURTH AVE WEST a5 e¢ Diary Vvrk eJ 5 i �e 9 u l G PP `P pr J �P ry J� G �y` Oyu qP �P "q 4p e 5qP % Figure A.4.2: Fourth Ave West ( MUELLE -R] Page 24 of 44 Table A.4.2-1: Fourth Avenue West ePulse®Condition Assessment Details Sensor Segment Internal Nominal Remaining °�0 Sensor 1 Pipe Change Segment Street Name 2 Length Diameter Thickness Thickness Location Location (ft) Material (in) (in) (in) from Nominal 231771AO05 Fourth Ave West 3446 3437 356 CAS 6 0.55 0.32 231771AO06 Fourth Ave West 3434 3437 527 CAS 6 0.55 NR 231771AO07 Fourth Ave West 3434 Echo-2 412 CAS 6 0.55 0.25 231771AO08 Fourth Ave West 3424 Echo-2 458 CAS 6 0.55 0.54 -2 *Access Points noted with the Echo prefix are appurtenances without available details on provided GIS,updates to Twin Falls asset numbers may be added with further GIS information A.4.3 ELDRIDGE AVE I 0 231T71AO09 231771A010 231771A011 231771AO12 eianage Oen.e �7 uyr Nvv we Figure A.4.3-1: Eldridge Ave 231771AO13 231771AO14 231771AO15 • Figure A.4.3-2: Eldridge Ave ( MUELLER) Page 25 of 44 Table A.4.3-1: Eldridge Ave ePulse®Condition Assessment Details Sensor Segment Internal Nominal Remaining % Segment Street Name Sensor 1 Pipe 2 Length Diameter Thickness Thickness Change Location Location (ft) Material (in) (in) (in) from Nominal 231771A009 Eldridge Ave 48966 14796 683 CAS 8 0.60 0.52 -13 231771A010 Eldridge Ave 48969 14796 636 CAS 8 0.60 0.42 -30 231771A0ll Eldridge Ave 48969 102-34 553 CAS 8 0.60 0.52 -13 231771A012 Eldridge Ave 39251 102-34 461 CAS 8 0.60 0.43 -28 231771A013 Eldridge Ave 39251 16436 527 CAS 8 0.60 0.45 -25 231771A014 Eldridge Ave 30826 16436 616 CAS 8 0.60 0.57 -5 231771A015 Eldridge Ave 30826 10546 451 CAS 8 0.60 0.44 -27 A.4.4 BLUE LAKES BLVD NORTH III 1 A 1 t .......... 231771A017 231771AO16 w WON pjenalnoa sajej only WON prenalnos same-I ants w W m N c.� 231771AQ21 231771A022 0 III � III ° n^ 3 3 p� ,p N l IE N 7 m a Figure A.4.4-1:Blue Lakes Blvd North [ MUELLER) Page 26 of 44 231771A018 231771AO17 ` N nlg ® 43JON PAenalnog sajej anlg w 4UoN pienalnog sai jej anlg _m 231771A019 231771AO20 231771 A021 Figure A.4.4-2:Blue Lakes Blvd North m ' d m 0 n Z 0 � Lynwood Shoppinq Bu Id nq Fremonr Drive 231771A023 �3 l� �i v m c Lynwood ? shopping H371j7 Center Lynwood 4o?3uilding Shopping 7 vew[h,ra Center _ a. B"r`et Building Lynwood 9 sami Shopping Z O Center 0 It 2Jini4.ilding ak.ira • US 93 Bus ' Javanese �. Steak:l�u se Ann,.. F„ne, Lynwood Figure A.4.4-3:Blue Lakes Blvd North [ MUELLER) Page 27 of 44 LA C /D O � EL2.0 dtQ 231771 AO2 7 T G ID Figure A.4.4-4:Blue Lakes Blvd North Table A.4.4-1: Blue Lakes Blvd North ePulse®Condition Assessment Details Sensor Segment Internal Nominal Remaining Sensor 1 Pipe Change Segment Street Name 2 Length Diameter Thickness Thickness Location Location Material from (ft) (in) (in) (in) jiminall 231771A016 Blue Lakes Blvd North 48316 191-2 488 CAS 20 1.03 0.67 231771A017 Blue Lakes Blvd North PH-199-1 191-2 264 CAS 20 1.03 0.68 231771A018 Blue Lakes Blvd North PH-199-1 29973 704 CAS 20 1.03 0.68 734 231771A019 Blue Lakes Blvd North 48722 48327 326 CAS 6 0.55 0.30 -45 231771A020 Blue Lakes Blvd North 48329 48327 310 CAS 6 0.55 0.35 -36 231771A021 Blue Lakes Blvd North 48329 49-581 545 CAS 6 0.55 0.36 -35 231771A022 Blue Lakes Blvd North PH-3002-1 49-581 237 CAS 6 0.55 0.43 -22 231771A023 Blue Lakes Blvd North 29977 48281 119 CAS 8 0.60 0.19 68 231771A024 Blue Lakes Blvd North PH-3084-1 48281 184 CAS 12 0.75 0.30 0 231771A025 Blue Lakes Blvd North PH-3084-1 Echo-1 398 CAS 8 0.60 0.48 -20 ( MUELLER) Page 28 of 44 Sensor Segment Internal Nominal Remaining % Segment Street Name Sensor 1 Pipe 2 Length Diameter Thickness Thickness Change Location Location (ft) Material (in) (in) (in) from Nominal 231771A026 Blue Lakes Blvd North 48690 Echo-1 280 CAS 8 0.60 0.50 -17 231771A027 Blue Lakes Blvd North 48690 Echo-5 409 CAS 8 0.60 0.37 *Access Points noted with the Echo prefix are appurtenances without available details on provided GIS, updates to Twin Falls asset numbers may be added with further GIS information. **Access Points noted with the PH prefix are potholes installed by Twin Falls for access directly to the watermain A.4.5 LOCUST ST SOUTH 231771AO28 231771AO29 ouch Locust Street South Locust Street South Figure A.4.5-1:Locust St South s ro 3 S r 231771Ao3o 231771A040 Locust StrW South Locust Street South -- r r � Figure A.4.5-2:Locust St South [ MUELLER) Page 29 of 44 Table A.4.5-1: Locust St South ePulse®Condition Assessment Details Sensor Segment Internal Nominal Remaining % Segment Street Name Sensor 1 Pipe 2 Length Diameter Thickness Thickness Change Location Location (ft) Material (in) (in) (in) from Nominal 231771AO28 Locust St South 48966 1098 1 616 CAS 12 0.75 0.59 -21 231771AO29 Locust St South 48965 1098-1 670 CAS 12 0.75 0.54 -28 231771AO30 Locust St South 48696 48282 629 CAS 4 0.52 NR 231771AO40 Locust St South PH-897-1 48282 626 CAS 4 0.52 0.407-23 **Access Points noted with the PH prefix are potholes installed by Twin Falls for access directly to the watermain A.4.6 MAIN AVE EAST a `P �J r �1 Bickel Elementary o� a� U53o School P� S sr ¢` S`s �r aJ \ � l US 30 Mag¢ Valley Veterinarian \ Hospital ti ~ 90Uv P�`Y ?Y 5, Krengels Hardware J The Car eIle 4f Store F y ��c o9 The Car WW Jar ce'` Store r ?fir a e \ t� as r J. k oaf 100 200ft 1 - X � yd Figure A.4.6:Main Ave East ( MUELLER) Page 30 of 44 Table A.4.6-1: Main Ave East ePulses Condition Assessment Details Sensor Segment Internal Nominal Remaining % Segment Street Name Sensor 1 2 Length Pipe Diameter Thickness Thickness Change Location Location Material from (ft) (in) (in) (in) Nominal 231771AO32 Main Ave East 87-771 48975 539 CAS 8 0.60 NR 231771AO33 Main Ave East 48976 48975 457 CAS 8 0.60 0.29 231771AO34 Main Ave East 48976 48700 488 CAS 8 0.60 0.61 231771AO35 Main Ave East 46072 48699 443 CAS 8 0.60 0.47 -22 A.4.7 ASH ST C G Y _ A 231MA039 731111AQ31 2�1 FT1AG3G 7i3175 y4y + Y Figure A.4.7-1:Ash St �o t 231771AO39 231771A03® aaa�15 usv la n d 4 4 n Figure A.4.7-2:Ash St ( MUELLER) Page 31 of 44 Table A.4.7-1:Ash St ePulse®Condition Assessment Details Sensor Segment Internal Nominal Remaining Sensor 1 Pipe Change Segment Street Name 2 Length Diameter Thickness Thickness Location Location Material from (ft) (in) (in) (in) Nominal 231771AO36 Ash St 27167 48972 570 CAS 4 0.52 0.34 231771AO37 Ash St PH-9483-1 48972 487 CAS 4 0.52 038 -27 231771AO38 Ash St PH-9483-1 88-783 445 CAS 4 0.52 0.25 231771AO39 Ash St 48971 88-783 471 CAS 4 0.52 0.25 **Access Points noted with the PH prefix are potholes installed by Twin Falls for access directly to the watermain A.4.8 STADIUM BLVD 231771AO41 231771AO42 N 231771A043 L-231771AO44 aa z° c zg E Figure A.4.8-1:Stadium Blvd Cascade Park r i 231771A044 231771A045 2311n 71�A 46 23111AG47 award �c 5rane�0oulevard -D CF O N 2 a Figure A.4.8-2:Stadium Blvd [ MUELLER) Page 32 of 44 Table A.4.8-1:Stadium Blvd ePulse®Condition Assessment Details Sensor Segment Internal Nominal Remaining 0 Sensor 1 Pipe Change Segment Street Name 2 Length Diameter Thickness Thickness Location Location (ft) Material (in) (in) (i 1) from Nominal 231771AO41 Stadium Blvd 2338 2018-1 408 CAS 8 0.60 0.41 231771AO42 Stadium Blvd 62-262 201- 1 430 CAS 8 0.60 0.43 -28 231771AO43 Stadium Blvd 62-262 47107 585 CAS 8 0.60 0.46 -23 231771AO44 Stadium Blvd 47919 47107 190 CAS 4 0.52 0.20 231771AO45 Stadium Blvd 47919 8861 616 CAS 4 0.52 0.26 231771AO46 Stadium Blvd 8859 8861 370 CAS 6 0.55 0.47 -15 231771AO47 Stadium Blvd 8859 9156 505 CAS 6 0.55 0.48 -13 **Access Points noted with the PH prefix are potholes installed by Twin Falls for access directly to the watermain A.4.9 FILLER AVE WEST 3 I � _ -231771Ao48_ A231771A050- I I i Figure A.4.9-1:Filler Ave West �231771AOS1 —� ue West —231771A052—' --- _ 0 --=231771AO58 Filer Avenue West P Figure A.4.9-2:Filler Ave West [ MUELLER) Page 33 of 44 • 2311/1 n U57 O ri,aveue w1', inosc n!n!nuss Figure A.4.9-3:Filler Ave West Table A.4.9-1: Filler Ave West ePulse®Condition Assessment Details o Sensor Segment Internal Nominal Remaining Segment Street Name Sensor 1 2 Length Pipe Diameter Thickness Thickness Change Location Location Material from (ft) (in) (in) (in) Nominal 231771AO48 Filler Ave West 48979 59-80 720 CAS 6 0.55 0.34 231771AO49 Filler Ave West 48994 59-80 738 CAS 6 0.55 0.26 231771AO50 Filler Ave West 48994 Echo-6 309 CAS 6 0.55 0.34 231771AO51 Filler Ave West 48293 Echo-6 533 CAS 6 0.55 0.35 231771AO52 Filler Ave West 48293 48296 352 CAS 6 0.55 0.43 22 231771AO53 Filler Ave West 48709 3274 384 CAS 10 0.68 NR 231771AO54 Filler Ave West 48709 48997 507 CAS 10 0.68 0.56 -18 231771AO55 Filler Ave West 48298 48997 424 CAS 10 0.68 0.58 -15 231771AO56 Filler Ave West 48298 48707 466 CAS 10 0.68 0.53 -22 231771AO57 Filler Ave West Echo-8 48707 280 CAS 10 0.68 0.53 -22 231771AO58 Filler Ave West Echo-8 48295 597 CAS 10 0.68 0.54 -21 *Access Points noted with the Echo prefix are appurtenances without available details on provided GIS, updates to Twin Falls asset numbers may be added with further GIS information. **Access Points noted with the PH prefix are potholes installed by Twin Falls for access directly to the watermain ( MUELLER) Page 34 of 44 APPENDIX B INTERPRETATION OF RESULTS BA ECHOWAVE®LEAK DETECTION When we discover a noise on a main, it can be classified as a leak or a point of interest (P01). If further investigation reveals negative results, it is classified as no leak discovered.Within all our reports, if no mention is made of leaks on a given section, it may be assumed that the result of the test is no leak discovered. No Leak Discovered When a negative correlation is matched with poor coherence, it is concluded that no leak was detected. In effect, there is no indication of a noise source of any sort,and therefore that there is no other evidence of leakage.Where possible,leak simulations are performed to confirm the absence of leaks and to ensure equipment functionality. Point of Interest(P01) A Point of Interest(1301)designation indicates that some,but not all,of the criteria for a positive leak detection result are met.This could mean that a strong correlation is observed but coherence is poor,or that there is no confirmation of leak noise through other test methods such as ground sounding or secondary correlation tests. This does not indicate a conclusive leak; however it is recommended that the City of Twin Falls perform a secondary investigation.This will confirm the presence and location of the leak, as there is evidence of some form of noise inside the pipe. Leak Three pieces of conclusive evidence must be acquired for a Point of Interest to be classified as a Leak.This includes but is not limited to the following methods of detection: • Leak correlation • Ground sounding • Acoustic sounding of fittings • Visual observation of moving water • Confirmation of chlorine residuals in stagnant water Several criteria must be metfor audio recordings in order to provide a positive leak detection result.This includes but is not limited to: • A clean distinctive correlation peak • An observable coherence level • Similar frequency spectra in each channel • A minimum amount of clipping in the time signal In some instances, more than one correlation test can be used as evidence to conclusively identify a leak. For instance, a field specialist can perform multiple correlation tests with sensors mounted to different pipe fittings. ( MUELLER) Page 35 of 44 B.2 EPULSE®CONDITION ASSESSMENT ePulse®condition assessment measures the mean hoop thickness(for asbestos cement or metallic mains)or mean hoop stiffness (for reinforced concrete).Where the original nominal thickness(or stiffness)is available,results are also presented as a percentage loss,and as a category indicating a qualitative description of the expected condition of the main. Qualitative Condition Description Categories The color-coding and descriptions in Table B.2-1:Color Coding and Hoop Thickness Loss Qualitative Descriptions are used for the results presented in all ePulse®condition assessment reports. Table B.2-1:Color Coding and Hoop Thickness Loss Qualitative Descriptions Change in Description Hoop Description Color Code Thickness Metallic Mains Less than 10% Good Green Minor levels of uniform corrosion or some localized areas with pitting corrosion. 10%to 30% Moderate Yellow Considerable levels of uniform surface or internal corrosion and/or localized areas of pitting corrosion. Greater than Poor Significant uniform corrosion and/or numerous areas of 30% 1 1 localized pitting corrosion. These descriptions are based on our experience and with validation of results through the exhumation of pipe samples tested. Following the table,more detail is provided as to the expected condition of differenttypes of main in each condition category,along with examples of validation of the ePulse®method on each type of main. Distribution of Degradation within Segments Each ePulse® result represents an average condition within a segment between two sensor attachment points. Pipe conditions may vary within a segment.The condition at any one point within the segment may not reflect the average conditions within that segment. The ePulse® method tests the mean hoop thickness of the pipe, which is not the same as the average thickness of the pipe. ePulse®measures a pipe's hoop stiffness: its resistance to axi-symmetric expansion under the tiny pressure variations caused by sound waves. Material properties are then used to calculate the hoop thickness which would provide exactly this stiffness.This is referred to as the mean hoop thickness. To obtain this same value mechanically,you would need to: divide a pipe into hoops; measure the thinnest section of structural material around the circumference of each hoop(i.e.graphite,tuberculation product,or asbestos cement with the calcium leached out would not be counted);and then average these. For example,any of the following descriptions will hold true for a pipe with a loss of 25%: 1. Circumferentially uniform loss of 25%along the entire segment. 2. Circumferentially uniform loss of 50%along half of the segment,but 0%loss along the other half of the segment. 3. Loss of 25%at the crown of the pipe along the entire segment, but 0% loss along any other point in the circumference along the entire segment. These descriptions hold true for asbestos cement,metallic and reinforced concrete mains. ( MUELLER) Page 36 of 44 Condition Interpretation in Metallic Mains Corrosion can occur in metallic pipes either in a localized area or in a generalized manner along the main. Examples of various levels of corrosion are presented in Figure B.2-5 below. Most of the degradation is often caused by a combination of internal corrosion, soil aggressiveness and coating defects on the surface of the main.If no coating was present upon installation,then the degradation would be due to soil aggressiveness alone. For cement mortar lined pipes, areas with higher losses may indicate the lining has been degraded to the point that the water column is now in contact with the metal, locally accelerating the degradation rate. This may also suggest that the soil loading conditions were such that the pipe experienced an over-deflection during its lifetime,causing damage to the interior lining. When considering the water aggressiveness as a mechanism for corrosion, it can be assumed that the degradation is relatively uniform across the length of the main. If pipes are unlined (bare), internal degradation may be attributed to a combination of localized pitting,and the formation of tuberculation that can also be accompanied by the formation graphitic corrosion (leaching of iron from the metal matrix). Localized corrosion is most likely due to isolated mechanisms such as direct current corrosion, or localized aggressive soil conditions.For cement lined pipes,areas with higher losses may indicate the lining has been degraded to the point that the water column is now in contact with the metal, locally accelerating the degradation rate. i 6" Cl pipe with 4.2% measured loss 6" Cl pipe with 47% measured loss 6" Cl pipe with 10% measured loss 18" Cl pipe with 18.5% measured loss Figure B.2-2:Examples of Different Levels of Corrosion in Metallic Pipe [ MUELLER) Page 37m44 Validation ^aoy the January 2O19. o total of173oPulsosva|idodonoeuUohovoboonpmvdodtounbyoornUonmorthin1pargos. Some clients have requested confidentiality; however vm are able topresent the result|naggregate. ePU|Se \/z|'r18t'On Results - All Materials 45= y= 0.916x + 0.9412 Rz = O.9003 ° wm ° 35° -- E um i� ,- um ~ �w ISu — ° um 0 � 5^ ".0 " , m `, 20 25 = o 40 m ePulse Thickness (nnnn) FigumB2-3:ePulses Validations On All Materials Two factors are worth attention in the charts. The R2 value is known as the coefficient of determination.This provides a measure of how well validation results are predicted by epu|oemreou|to. |tiathopmportionoftota|variadonofoutoomooinve|idationroau|taoxp|ainodbytheoPu|semreou|to.AnRcof1 indicates that the data match perfectly,while an R2 of 0 indicates that the ePulse@ results cannot be used to predict the validated results at all. For non-destructive testing methods,an R2 value above 0.5 represents strong predictive power. The correlation coefficient R is the square root of the nu value. For oxomp|o. on Ru value ofO.5 means the same thing as a correlation of071. The equation(y=a+Dx)indicates how well calibrated the ePulseOD measurements are,on average.Values of a close to zero,and of P close to 1,indicate good calibration.For non-destructive testing methods,a P greater than 0.5 and an a less than 25%of the average value represent good calibration. Note that the variation between the ePulses results and validation measurements is notthe same thing as the error in the ePulse(@ results.It is actually the combination of the error in the ePulse@ results and the random variation in point samples versus the true average. ComporingoPu|oos results mthe results of validations will over-estimate the ootuo| error in the oPu|oos voou|to.The reason for this is thatthe ePulseOD results are averages over segments of about 100 m(300")in length,whereas the validation results indicate the thickness at a one point or a small sub-segment.Each validation measurement will have a random error versus the true average over that segment.The difference between an ePulsel@ measurement and a validation measurement can be understoodoo: oPulsos Validated~(oPulsos- Troo-Avorage)+(Truo_A,orage- Validated) Page 38 of 44 Even if the ePulse®results perfectly match the true average(ePulse®-True-Average=0),we would still expect to see a difference between validation results and ePulse®: ePulse®-Validated=(True Average- Validated) Actual pipe conditions will vary randomly along the sample, so the difference between the true average and validation results should be a normal distribution centered around zero.If ePulse®is effectively measuring the true average,we should see the same pattern in the difference between the ePulse®and Validated results.The actual distribution is shown in Figure B.2-4,and appears to match the expected pattern. Variance - ePulse vs Validation (mm) 25 20 15 10 5 0 ■ 1 ■ ■ -10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 Figure B.2-4:Variance between ePulse®results and validation results There are a small number of outliers, which likely represent errors in those ePulse® measurements.The remainder of the data match the expected normal distribution. ( MUELLER) Page 39 of 44 B.3 LIMITATIONS The accuracy of the final results presented in this report can be impacted by a certain factor.The following are some of the factors that affect the accuracy of results. MODULUS OF ELASTICITY The modulus of elasticity of the pipe material is one of the factors in the calculation of the mean hoop thickness.While we have significant experience estimating the modulus of elasticity based on the material,age,and region of manufacture,we can improve the accuracy of the results by testing the actual modulus of elasticity of an exhumed sample of the pipe. If interested, please contact us for more information. PIPE SPECIFICATIONS Detailed pipe specifications were not available for all pipes surveyed.Although we have made reasonable assumptions for internal diameter, material and original hoop thickness, the results can be improved if accurate pipe specifications can be provided. If original specifications cannot be located,the City of Twin Falls may wish to exhume a pipe coupon to verify diameter,material,and thickness assumptions. STATISTICAL VARIATION The values generated by ePulse®testing are averaged for a segment of pipe which ranges in length from 150 feet to 500 feet.This averaging allows for the possibility of having small lengths within the segment which are severely degraded.This degradation will not be shown in the final result.Therefore, it is important to note that the value presented describes the general condition of the pipe and may not show future potential point failures. ( MUELLER) Page 40 of 44 B.4 SENSITIVITY ANALYSES AND CONSIDERATIONS Several variables may affect accurate analysis: • Inaccurate distance measurements • Variance in manufacturing tolerances • Variance in the modulus of elasticity of the material • Unknown pipe repairs • Inadequate correlation signals. We are constantly committed to reducing error during every step of the testing process. Distance Measurement An accurate distance measurement is crucial for an accurate assessment. In general, a 1%error in distance measurement can result to more than a 2%error in final percentage of thickness lost. For this reason, our preference is to use potholes or in-line valves,as these provide the most accurate distance measure,since it is a point-to-point measurement.As the number of bends and/or elevation changes between the sensor connection points increases, so does the potential error in the distance measurement. Pipe Manufacturing Tolerances Small differences in nominal specifications will occur between pipes due to differences in manufacturers and tolerances.These differences commonly range from between 5% and 10% depending on the manufacturer and the material. Furthermore, a contractor may have installed a pipe that exceeds the minimum specifications. Under these circumstances the measurements may show a pipe with a hoop thickness that is greater than expected. This is particularly true of older pipes as their tolerances were not adhered to as strictly. The material properties used for calculations are selected using conservative estimates. This provides for a worst-case scenario analysis. Repair Clamps on Previous Leaks Acoustic waves are primarily water borne.As such, a small number of repair clamps will have an insignificant effect on the test results,since the acoustic wave will bypass the clamps. Modulus of Elasticity A change in elastic modulus of 10%will cause a change in the calculated thickness by approximately 10%.The elastic modulus is known for common materials used in the manufacturing of pressure pipe, but this value can vary among manufacturers. It is dependent on the manufacturing process and the quality of the material.The material properties used for calculations are selected using conservative estimates.This provides for a worst-case scenario analysis. Unaccounted for Replacement of Pipe Sections During Repairs Acoustic waves propagate differently depending upon the pipe material. This effect remains true for unaccounted short pipe replacements with different materials and can result in significant error. For example,a new 6 meter long(-20 feet)ductile iron repair in a 100 meter long(-328 feet)cast iron pipe section of average condition,will produce a small error of+3.5%in measured hoop thickness.However,the same repair made with PVC pipe would produce an error of-41%in measured hoop thickness. Preferably, pipe sections selected for testing should be free of repaired sections. However, if this condition does not exist, the impact of the repaired pipe section can be accounted for, provided accurate information is available for the age, location, length, material type,and class of the repair pipe section. Inadequate Correlation Signals Inadequate correlation signals can sometimes occur in the field. The following are some of the conditions that may cause an inadequate correlation: 1. The presence of plastic repairs in metallic pipes which can cause poor propagation of sound. 2. Loose or worn components in fittings used for the measurements,such as valve or hydrant stems. 3. Large air pockets in the pipe which heavily attenuate acoustic signals. 4. Heavily tuberculated pipe,particularly old cast iron or unlined ductile iron pipes,which can attenuate the acoustic signals to such an extent that a correlation is of very low quality. ( MUELLE -R] Page 41 of 44 APPENDIX C DETAILED METHODOLOGY CA LEAK DETECTION The methodology employed is known as the cross-correlation method.A correlator listens passively for noise created by a leak.If one is detected, it uses the time delay between sensors to determine the position of the leak.The following procedure was used to conduct the leak detection survey: 1. For each location surveyed,the distance between the sensors was measured. 2. Sensors were mounted either directly on the pipe or were connected to the water column with hydrophones. 3. A correlation measurement was performed without introducing noise(known as a background recording),and the signal was saved to the computer so that further analysis could be performed off-site.A preliminary analysis is performed on- site to determine if any leaks are present. ( MUELLER) Page 42 of 44 C.2 EPULSEO MEAN HOOP THICKNESS TESTING A section of pipe is the length bracketed by two contact points on the main.An out-of-bracket noise source is located outside of that segment. A known noise source may be used to determine the acoustic wave velocity in a segment of pipe. Knowing the distance between the sensors,the acoustic wave velocity(v)will be given by v=d/t,where d is the length of pipe between the sensors,and t is the time taken for the acoustic signal to propagate between the two sensors. The following procedure is followed to conduct an ePulse®data collection survey: 1. A leak detection survey is performed on the length of pipe to check for the presence of existing leaks. (Described in previous section) 2. A noise source is created "out-of-bracket". A variety of different noise sources can be used including an existing leak noise,blow-off noise,pump noise,impulse noise,running a fire hydrant,tapping on a fire hydrant,or directly on the pipe. 3. A new correlation measurement is performed and stored as a wave file for further analysis and confirmation off-site.Data is analysed further to obtain an optimum correlation,ensuring an accurate velocity measurement. Wave Velocity Equation The general form of the acoustic pipe integrity testing equation is shown below. Equation C.2-1:Wave Velocity-Thickness Model 1 V = V, X [1 + (L9 X (E`)] F v: measured velocity vo.propagation velocity in an infinite body of water D;:pipe internal diameter Ki:bulk modulus of the liquid E:elastic modulus of the pipe material t,: residual thickness of the pipe Bulk Modulus of Water Calibration Different water sources often produce a different bulk modulus of water. The bulk modulus essentially represents the water's inherent resistance to compression,and is impacted by factors like water temperature,dissolved salts and entrained air.Our field specialists calibrate the bulk modulus at each water company's water source.This requires performing a single test on a stretch of pipe with a known pipe condition. In practice,this generally means performing an additional test on a new section of pipe that has been installed within the past few years. ( MUELLER) Page 43 of 44 APPENDIX D ABBREVIATIONS Cl Cast Iron:Pipe wall construction consisting of cast iron.This includes pipes classified as pit cast iron or spun cast iron as well. CL Concrete lined: Indicates whether or not a specific pipe type has some form of concrete lining. This abbreviation will typically follow a pipe type abbreviation Ex:DICL for ductile iron concrete lined. DI Ductile Iron: Pipe wall construction consisting of ductile iron. GIS Geographic Information System:A system designed to capture,store, manipulate,analyze, manage,and present all types of spatial or geographical data. GPS Global Positioning System:a global system of satellites used to provide precise positional data and global time synchronization. IB In-Bracket. Please refer to the technical glossary. OOB Out-of-Bracket. Please refer to the technical glossary. PCI Pit Cast Iron:Pipe wall construction consisting of pit cast iron. PE Polyethylene: Pipe wall construction consisting of polyethylene. POI Point of Interest.Please refer to the technical glossary. PVC Poly Vinyl Chloride: Pipe wall construction consisting of polyvinyl chloride. SCI Spun Cast Iron: Pipe wall construction consisting of spun cast iron. ( MUELLER) Page 44 of 44 APPENDIX E GLOSSARY OFTECHNICAL TERMS Acoustic Wave Also known as:wave speed,wave velocity,velocity.The speed at which a coupled-mode pressure Speed wave travels along a pipe. Blue/White Station A piece of equipment where a sensor is connected to transmit the data to a central location. Typically,stations are colour coded blue or white. Coherence Measure of similar vibration frequency between two channels(Blue and White stations or a node pair). Correlation The process of comparing two acoustic signals for similarity in the time domain.Echologics technologies use correlation to judge the time delay between two signals.This allows for determination of the location of leaks along a pipeline. In-Bracket A noise source that is within the span of pipe between two Stations or Nodes. Leak Discovered A point along a pipe that is likely losing water to the surrounding soil and environment. For a leak to be classified as discovered,a field technician must acquire at least three pieces of unique evidence that suggest existence and location. No Leak No evidence of leakage was discovered,or a P01 was under investigate and it was determined that Discovered it was not a leak. Node A piece of equipment where a sensor is connected to transmit the data to a central location. Typically, nodes are paired with other nodes as part of a large array installed on a pipeline or in an area. Out-of-Bracket A noise source that is outside the span of pipe between two Stations or Nodes. Point of Interest Evidence of some form of noise or energy on the pipe.There is not enough evidence to classify a point of interest as a leak. Segment A section of pipe surveyed in one measurement.The length of the segment is the distance between two sensors. Sensor A device used to measure physical or chemical properties of a system. In the context of this report this term will be typically used as a reference to a vibration sensor. Site A neighbourhood or area within which a segment of pipe exists. ( MUELLER)