EPA/600/R-09/048 | May 2009 | www.epa.gov /nrmrl 

Rehabilitation of Wastewater 

Collection and Water 

Distribution Systems 

67$7(2)7(&+12/2*<5(9,(:5(3257

Office of Research and Development

National Risk Management Research Laboratory - Water Supply and Water Resources Division 
EPA/600/R-09/048 

May 2009 

State of Technology Review Report 

on 

Rehabilitation of Wastewater Collection 

and Water Distribution Systems 

by 

Dr. Ray Sterling 

Trenchless Technology Center at Louisiana Tech University 

Lili Wang, P.E. 

Battelle Memorial Institute 

Robert Morrison, P.E. 

Jason Consultants, LLC 

Contract No. EP-C-05-057 

Task Order No. 58 

for 

Dr. Ariamalar Selvakumar 

Task Order Manager 

U.S. Environmental Protection Agency 

National Risk Management Research Laboratory 

Water Supply and Water Resources Division 

2890 Woodbridge Avenue (MS-104) 

Edison, NJ 08837 

National Risk Management Research Laboratory 

Office of Research and Development 

U.S. Environmental Protection Agency 

Cincinnati, Ohio 45268 

March 2009
 
DISCLAIMER 

The work reported in this document was funded by the United States Environmental Protection Agency 

(EPA) under Task Order (TO) 58 of Contract No. EP-C-05-057 to Battelle. This document has been 

subjected to the Agency’s peer and administrative review and has been approved for publication. Any 

opinions expressed in this report are those of the author (s) and do not necessarily reflect the views of the 

Agency, therefore, no official endorsement should be inferred. Any mention of trade names or 

commercial products does not constitute endorsement or recommendation for use. 

ii 
EXECUTIVE SUMMARY 

As part of the U.S. Environmental Protection Agency’s (EPA) Aging Water Infrastructure Research 

Program, which directly supports the Agency’s Sustainable Water Infrastructure Initiative, scientific and 

engineering research is being conducted to evaluate and improve promising innovative technologies that 

can reduce costs and improve the effectiveness of operation, maintenance, and replacement of aging and 

failing drinking water distribution and wastewater conveyance systems (EPA, 2007a). Task Order (TO) 

58 (under EPA STREAMS Contract No. EP-C-05-05758) is being conducted by Battelle, in cooperation 

with the Trenchless Technology Center (TTC) at Louisiana Tech University, Jason Consultants, and 

Virginia Tech, to perform a comprehensive review and evaluation of existing and emerging rehabilitation/ 

repair technologies for wastewater collection and water distribution systems, and select and prepare them 

for field demonstration. 

This State of Technology Review Report provides an overview of the current state-of-the-practice and 

current state-of-the-art for rehabilitation of pipes and structures within the wastewater collection and 

water distribution systems. The State of Technology Review Report discusses the common issues that cut 

across both water and wastewater applications, including the need for rational and common design 

approaches for rehabilitation systems, quality control/quality assurance (QA/QC) procedures and 

acceptance testing during installation of rehabilitation systems, decision support for choice of 

rehabilitation vs. replacement and choice of rehabilitation systems, and special applications of 

rehabilitation under challenging conditions such as elevated liner service conditions adjacent to steam 

lines and high pressure pipe lining systems. It also discusses separate issues for water and wastewater 

systems in terms of drivers for increased rehabilitation efforts and problems typically encountered. The 

State of Technology Review Report examines the state-of-practice for rehabilitation in the water and 

wastewater sectors and the potential for improvement within the general classes of rehabilitation systems. 

It identifies some emerging technologies as candidates for potential field demonstration and cross-cutting 

innovation potential. The organization of a field demonstration program is also discussed. 

The document was used as a basis for discussions at an International Technology Forum, which was held 

on September 9 to 10, 2008, at Edison, NJ as part of the project activities. Participants in the Forum were 

invited to provide their degree of concurrence with the descriptions of the state of the industries, discuss 

different viewpoints as appropriate, propose additional issues to be considered, and present information 

on specific technological advances underway in North America and elsewhere in the world. The State of 

Technology Review Report and Forum contributions together provide documentation and analysis of the 

current status of technology and practice for rehabilitation of water and wastewater systems in North 

America and elsewhere in the world and clear guidance on how the demonstration activities planned 

within the project can best contribute to advancing the technology and accelerating the adoption of 

favorable approaches. 

In many ways, the response of government and industry, once the problem of deteriorating water and 

wastewater infrastructure was fully acknowledged, has shown real progress. A suite of technologies for 

the rehabilitation of water and wastewater assets that do not require their full excavation and replacement 

has been developed over the past 30 to 40 years, and these trenchless technologies have made a 

significant penetration into the U.S. market; estimates of the proportion of rehabilitation work carried out 

using trenchless techniques range up to 70 percent in the sewer sector and up to 31 percent in the water 

sector. The variety of tools available to the water or sewer utility engineer today is remarkably different 

than it was during the 1960s. However, the average rate of system rehabilitation and upgrading is not 

adequate to keep pace with increasing needs, quality demands and continually deteriorating systems. The 

opportunity lies in the fact that while the tools being used today are generally effective, there is still 

considerable room for improvement in existing technologies and/or development of new technologies. 

Such improvements or new technologies offer the chance to make the investments in rehabilitation more 

iii 
 

effective and extend the ability of utilities and local governments to fix larger portions of their systems 

with current funding levels. A secondary benefit is to increase the political and public will to spend 

additional money on fixing this problem. 

The current EPA research program is aimed at encouraging the introduction of new and improved 

technologies into the U.S. marketplace for water and wastewater systems rehabilitation. It will also 

develop the protocols for demonstration projects that will provide exposure and application data for novel 

and emerging technologies through the planning and execution of two demonstration projects. A broader 

set of demonstration projects will then follow in the future. The selection of technologies that will benefit 

from the formal demonstration project and which have a significant potential for market penetration in the 

future has also been examined. A key aspect of the planned program is that each demonstration will not 

only record the use of a particular technology but will provide a documented case study of the technology 

selection process, the project design, the QA/QC, and the preparation for the life-cycle management of the 

asset. 

In summary, this State of Technology Review Report was intended to document the research team’s 

assessment of the needs and opportunities of water and wastewater infrastructure rehabilitation. The State 

of Technology Review Report also aids in the planning and development for technology selection and 

field demonstrations to address the knowledge gaps identified herein. In addition, comments to this State 

of Technology Review Report were solicited from the project stakeholder committee and at the 

International Technology Forum and incorporated into this final document as appropriate. Finally, the 

key outcomes and recommendations from the International Technology Forum are presented. 

iv 
FOREWORD 

The U.S. Environmental Protection Agency (EPA) is charged by Congress with protecting the Nation’s 

land, air, and water resources. Under a mandate of national environmental laws, the Agency strives to 

formulate and implement actions leading to a compatible balance between human activities and the ability 

of natural systems to support and nurture life. To meet this mandate, EPA’s research program is 

providing data and technical support for solving environmental problems today and building a science 

knowledge base necessary to manage our ecological resources wisely, understand how pollutants affect 

our health, and prevent or reduce environmental risks in the future. 

The National Risk Management Research Laboratory (NRMRL) is the Agency’s center for investigation 

of technological and management approaches for preventing and reducing risks from pollution that 

threaten human health and the environment. The focus of the Laboratory’s research program is on 

methods and their cost-effectiveness for prevention and control of pollution to air, land, water, and subsurface resources; protection of water quality in public water systems; remediation of contaminated sites, 

sediments and ground water; prevention and control of indoor air pollution; and restoration of ecosystems. NRMRL collaborates with both public and private sector partners to foster technologies that 

reduce the cost of compliance and to anticipate emerging problems. NRMRL’s research provides 

solutions to environmental problems by: developing and promoting technologies that protect and improve 

the environment; advancing scientific and engineering information to support regulatory and policy 

decisions; and providing the technical support and information transfer to ensure implementation of 

environmental regulations and strategies at the national, state, and community levels. 

This publication has been produced as part of the Laboratory’s strategic long-term research plan. It is 

published and made available by EPA’s Office of Research and Development to assist the user 

community and to link researchers with their clients. 

Sally Gutierrez, Director 

National Risk Management Research Laboratory 

v 
ACKNOWLEDGEMENT
 

We would like to acknowledge several key contributors to the State of Technology Review Report 

including Ed Kampbell, Tom Sangster, and Declan Downey of Jason Consultants, Erez Allouche and 

Jadranka Simicevic of Louisiana Tech University, Wendy Condit of Battelle, and Sunil Sinha of Virginia 

Tech University. The authors would like to thank our stakeholder group members for providing written 

comments. Our sincere appreciation also extends to those who provided verbal review comments during 

the project’s Technology Forum held on September 9 and 10, 2008 at Edison, NJ. Both written and 

verbal comments have been incorporated into this final document as appropriate. 

vi 
 

CONTENTS
 

DISCLAIMER ..............................................................................................................................................ii 

EXECUTIVE SUMMARY .........................................................................................................................iii 

FOREWORD ................................................................................................................................................v 

ACKNOWLEDGEMENT ...........................................................................................................................vi 

APPENDICES .............................................................................................................................................ix 

FIGURES.....................................................................................................................................................ix 

TABLES ......................................................................................................................................................ix 

1.0 INTRODUCTION .................................................................................................................................1 

1.1	 Purpose of State of Technology Review Report........................................................ 1 

1.2	 Development of Rehabilitation Practices ................................................................. 1 

1.3	 Current Market ...................................................................................................... 2 

1.4	 History of Wastewater Rehabilitation ...................................................................... 4 

1.5	 State of Technology Review Report Organization .................................................... 4 

2.0 COMMON ISSUES FOR REHABILITATION TECHNOLOGIES ....................................................5 

2.1	 Need for Rational and Common Design Approach for Rehabilitation Systems ........... 5 

2.2	 QA/QC Procedures for Rehabilitation Technologies................................................. 6 

2.3	 Decision Support for Choice of Rehabilitation vs. Replacement and Choice of 

Rehabilitation Systems ........................................................................................... 8 

2.4	 Special Applications............................................................................................... 9 

2.4.1 Elevated Temperature Liner Service Conditions............................................................9 

2.4.2 Relining of High Pressure Piping Systems ...................................................................10 

3.0 WASTEWATER SYSTEM ISSUES...................................................................................................11 

3.1	 System Characteristics.......................................................................................... 11 

3.2	 Drivers for Increased Rehabilitation Efforts ........................................................... 12 

3.2.1 National Pollutant Discharge Elimination System (NPDES) .......................................12 

3.2.2 Sanitary Sewer Overflows (SSOs)................................................................................12 

3.2.3 Combined Sewer Overflows (CSOs) ............................................................................12 

3.2.4 Capacity, Management, Operation, and Maintenance (CMOM) Program ...................13 

3.2.5 Government Accounting Standards Board (GASB) Statement No. 34.........................13 

3.2.6 Rehabilitation Funding..................................................................................................13 

3.3	 Problems Typically Encountered in Wastewater Pipe Systems ................................ 14 

3.3.1 Gravity Sewers..............................................................................................................14 

3.3.2 Laterals..........................................................................................................................14 

3.3.3 Force Mains ..................................................................................................................18 

3.3.4 Pump Stations and Lift Stations....................................................................................18 

3.3.5 Drop Shafts ...................................................................................................................20 

3.3.6 Manholes and Other Chambers.....................................................................................20 

3.4	 Other Wastewater Issues....................................................................................... 21 

3.4.1 Inspection and Assessment ...........................................................................................21 

3.4.2 Inspection and Condition Assessment Standards..........................................................22 

3.5	 Summary for Wastewater System Issues................................................................ 22 

4.0 WATER SYSTEM ISSUES ................................................................................................................24 

vii 
 

4.1 Background ......................................................................................................... 24 

4.1.1 Infrastructure Investment Needed.................................................................................24 

4.1.2 Pipe Material Usage ...................................................................................................... 24 

4.1.3 Drivers for Water System Rehabilitation......................................................................27 

4.1.4 Funding for Rehabilitation ............................................................................................28 

4.1.5 Potable Water – NSF International (NSF)/American National Standards 

Institute (ANSI) Standard 61 ........................................................................................28 

4.1.6 Service Connections......................................................................................................29 

4.1.7 Experienced Contractors...............................................................................................29 

4.1.8 Standards.......................................................................................................................29 

4.1.9 Maintenance Concerns..................................................................................................30 

4.2 Summary for Water System Issues ........................................................................ 30 

5.0 CURRENT TECHNOLOGIES AND POTENTIAL FOR IMPROVEMENT...................................32 

5.1 Sliplining............................................................................................................. 32 

5.2 Spiral-Wound Liners ............................................................................................ 32 

5.3 Cured In Place Pipe Liners.................................................................................... 33 

5.4 Close-Fit Liners ................................................................................................... 33 

5.5 Grout-In-Place (GIP) Liners ................................................................................. 33 

5.6 Panel Liner Systems............................................................................................. 33 

5.7 Sprayed Coating and Liner Systems ...................................................................... 33 

5.8 Flood Grouting .................................................................................................... 34 

6.0 EMERGING OR NOVEL TECHNOLOGIES ....................................................................................39 

6.1 Potential Technology Candidates for Demonstration .............................................. 39 

6.2 Cross-Cutting Innovation Potential........................................................................ 41 

6.2.1 New Materials...............................................................................................................41 

6.2.2 Wastewater Innovations................................................................................................42 

6.2.3 Water Innovations.........................................................................................................42 

6.2.4 Decision Support...........................................................................................................42 

6.2.5 Accelerating Adoption of New Technologies...............................................................45 

6.2.6 Observations on Successful Programs.................................................................... 47 

7.0 EPA DEMONSTRATION PROJECTS...............................................................................................48 

7.1 Purpose of Technology Demonstration .................................................................. 48 

7.2 Previous Demonstration Projects and Benefits of Demonstration............................. 48 

7.3 Special Aspects of Planned EPA Demonstration Project ......................................... 49 

7.3.1 Demonstrate Application of Consistent Design Methodologies and Decision 

Support Approaches to the Selected Technologies.......................................................49 

7.3.2 Demonstrate Application of Appropriate QA/QC and Post-Installation 

Procedures.....................................................................................................................49 

7.3.3 Demonstrate Life-Cycle Plan for Ongoing Evaluation of Rehabilitation 

Performance ..................................................................................................................50
 

7.3.4 Document Data from Demonstration............................................................................50 

7.3.5 Provide an Assessment of Selected Technology, Expected Range of 

Applications, Avenues for Improvements.....................................................................50 

7.4 Demonstration Approach...................................................................................... 51 

7.4.1 Technology Selection Criteria.......................................................................................51 

7.4.2 Site Selection Criteria ...................................................................................................51 

viii 
 

7.4.3 Demonstration Protocols and Metrics...........................................................................53 

7.4.4 Demonstration Trials.....................................................................................................53 

7.4.5 Invitation to Apply and Selection Process for Future Demonstration ..........................53 

8.0 FORUM OUTCOMES AND RECOMMENDATIONS .....................................................................55 

9.0 REFERENCES ....................................................................................................................................58 

APPENDICES 

Appendix A: Abbreviations 

Appendix B: Wastewater Pipe Rehabilitation Technology Descriptions 

Appendix C: Water Pipe Rehabilitation Technology Descriptions 

Appendix D: Manhole Rehabilitation Technology Descriptions 

Appendix E: Example Quality Control Standards for Pipe Rehabilitation 

FIGURES 

Figure 1. Private Ownership of Sewer Laterals.........................................................................................17
 

Figure 2. Main Causes of Failure in Ferrous and Non-ferrous Force Mains.............................................19
 

Figure 3. Historical and Projected Average Age of U.S. Water System....................................................24
 

Figure 4. Selection of Rehabilitation Techniques to Solve Structural Problems.......................................44
 

Figure 5. Conceptual Framework for Selecting Appropriate Technologies ..............................................45
 

TABLES 

Table 1. Gravity Sewer System: Percent Distribution by Material and Diameter Range .......................11 

Table 2. Force Main Systems: Percent Distribution by Pipe Materials and Diameter Ranges...............12 

Table 3. Main Defects in Gravity Sewer Systems by Sewer Material....................................................15 

Table 4. Water Distribution Systems by Material...................................................................................25 

Table 5. Water Distribution Systems by Diameter .................................................................................25 

Table 6. Water Distribution Systems by Age..........................................................................................25 

Table 7a. Overview of Sewer Pipe Rehabilitation Methods—Mature Technologies...............................35 

Table 7b. Overview of Sewer Pipe Rehabilitation Methods—Emerging Technologies...........................36 

Table 7c. Overview of Sewer Pipe Rehabilitation Methods—Novel Technologies.................................36 

Table 8. Overview of Water Pipe Rehabilitation Methods.....................................................................37
 

Table 9. Overview of Manhole Rehabilitation Methods.........................................................................38 

Table 10. Novel and Emerging Trenchless Pipeline Rehabilitation Methods ..........................................39 

Table 11. Novel and Emerging Technologies for Manhole Rehabilitation ..............................................41 

Table 12. Novel and Emerging Trenchless Methods for Rehabilitation of Wastewater Laterals.............41
 

ix 
 

1.1 

1.2 

1.0 INTRODUCTION 

Purpose of the State of Technology Review Report 

This State of Technology Review Report is intended to provide an overview of the current state-of-thepractice and current state-of-the-art for rehabilitation of pipes and structures within the wastewater 

collection and water distribution systems. Rehabilitation is defined as repair, renewal, and replacement of 

components to return the system to near-original condition and performance. The document was 

produced for use as a basis for discussions in an International Technology Forum, which was held on 

September 9 to 10, 2008 as part of the U.S. Environmental Protection Agency (EPA) project 

Rehabilitation of Wastewater Collection and Water Distribution Systems (Contract No. EP-C-05-057, 

Task Order No. 58 [TO 58]). Participants in the Forum were invited to comment on the descriptions of 

the state of the water infrastructure technology industry, provide different viewpoints as appropriate, 

propose additional issues to be considered, and present information on specific technological advances 

underway in North America and elsewhere in the world. The State of Technology Review Report and 

Forum contributions together provide a clear documentation and analysis of the current status of 

technology and practice for rehabilitation of water and wastewater pipe systems in North America and 

clear guidance on how the demonstration activities planned within the project can best contribute to 

advancing the technology and accelerating the adoption of favorable approaches. The key Forum 

recommendations are included in this report in Section 8. While there is also an urgent need to 

understand system-wide issues in the operation of water and wastewater systems (e.g., the interaction of 

wet weather flow with wastewater treatment plant operation), this project and State of Technology 

Review Report are focused on the rehabilitation of the pipe systems themselves. 

Development of Rehabilitation Practices 

Some aspects of drainage and sewer systems can be dated back at least to 4,000 – 2,400 BC. 

Archeological evidence (Schladweiler, 2002) indicates that in the Mesopotamian Empire, during this 

period, stormwater drain systems were constructed using sun-baked bricks or cut stone, and clay was 

molded to form pipes, tees, and angle joints. A later example (dating from approximately 1,500 – 1,300 

BC) of a street drainage channel covered over with a stone slab and clay drainage pipes can be found in 

the archaeological excavations at the site of the City of Troy in present day Turkey (Troia, 1999). 

In Roman times, both storm and sanitary sewer systems were already in use; water supply systems 

involving complex aqueduct systems and lead piping within houses can still be observed in old Roman 

settlements. The “dark ages” and even the Renaissance period saw this acquired “know how” disappear, 

resulting in dire unsanitary conditions in urban areas in many parts of the world. Urban conditions were 

made much worse by the industrial revolution, which brought an influx of poor residents to the cities and 

resulted in high-density urban development with little access to fresh water or sanitation. Paris introduced 

sewer pipes and tunnels during the 13th century AD. In 1854, John Snow made the connection between 

communicable diseases and clean water supply and sanitary conditions in London, which launched a 

“modern” wave of construction of better water supply and distribution systems and increased attention to 

sewerage needs. However, it took the “great stink” of 1858 along the River Thames to goad the English 

parliament into approving the creation of a drainage system to carry the polluted water in tunnels to be 

discharged well downstream of the capital city. Improved water supply and sewerage systems quickly 

spread to many other cities in the Western world, although effective treatment of collected sewage often 

lagged many decades behind the decision to transport and discharge it into receiving waters away from 

populated areas. Some of the original systems installed in many cities are still in operation and in good 

condition, but many portions of systems (including portions installed only a few decades ago) are in poor 

condition and continue to deteriorate. 

1
 
 

 

From this deliberately simplified synopsis, the evolution and persistence of many of the issues that 

surround the design, operation and maintenance of water distribution and sewage collection systems can 

be seen. For example: 

	 Even once systems are created, continued good government and maintenance of know 

how are necessary to retain effective and operational systems. 

	 The materials that were used in pre-historical and Roman water and sewer systems (stone, 

clay and lead) can still be found in useable condition today (i.e., potentially a life of 

2,000+ years). 

	 There appears to be a natural tendency among human groups to solve a pollution or water 

supply problem only enough to meet the group’s own local or near-term needs. This has 

resulted in unsustainable withdrawal of aquifer water supplies in arid regions, discharge 

of minimally treated sewage to rivers and coastal waters, and the lack of investment in 

maintaining systems, resulting in the inter-generational transfer of these liabilities. 

	 Disastrous events are often the catalyst for the political will to “fix the problem.” 

	 Most modern water and sewer systems are less than 200 years old. 

	 One can find many pipes over 100 years old still in good condition although functionality 

may be impaired by such issues as tuberculation in water systems. 

	 The deterioration of underground piping systems shows a high degree of variation even 

among nominally the same piping material, due to variations in the quality of the 

manufactured product over decades, construction quality, joint type, ground conditions, 

and water or effluent chemistry. This makes age alone an insufficient barometer of the 

operational health of a system. 

	 The longevity of the basic elements of many old piping materials is evident, but they may 

be impractical for continued usage today due to issues of cost, inability to resist 

settlement, heavy traffic loadings or deep burial, and health related effects (e.g., lead 

piping). In some cases, adaptations of old piping systems appear to provide effective and 

long-lived systems (e.g., flexible, gasketed jointing systems for clay pipes). 

Other issues affecting the effective maintenance and rehabilitation of water and sewer systems include: 

	 Innovation provides the path to better piping and renovation systems; however, initially 

promising materials sometimes turn out later to exhibit serious drawbacks, resulting in 

changes to a significant element of a piping or renovation system. This could reset the 

experience clock back to zero. 

	 Public works has a strong reputation for conservatism in the adoption of new materials 

and technologies. The desire for uniformity in materials with respect to maintenance and 

replacement and the fear of repercussions for choosing materials that later turn out to be 

problematic are key drivers for this conservatism. 

Current Market 

The annual market for rehabilitation of wastewater infrastructure in the U.S. in 2003 was reported to be 

approximately $4.5 billion. This market has shown consistent growth of 8 to 10 percent per annum for 

approximately 10 years. Underground Construction magazine also conducts an annual survey of 

municipalities and prepared an estimate for the 2007 sewer rehabilitation market at $3.3 billion and the 

2
 

1.3
 

new sewer construction market at $4.4 billion. They further derived from their survey that 69.7 percent of 

the sewer rehabilitation work was done using trenchless methods compared to 16.1 percent for new sewer 

construction (Underground Construction, 2008) although it was not clear whether the survey responses 

came mostly from those cities who were using trenchless methods. In any event, it is clear that trenchless 

methods have made significant penetration into the water and sewer rehabilitation markets. 

The sewer rehabilitation market in the rest of the world is approximately as large as that in the U.S., i.e., 

the U.S. accounts for approximately 50 percent of the world market. Relatively consistent markets exist 

in Canada, Europe, Japan, Australia, and Singapore. In these countries, the market structure in terms of 

technologies used is similar to that in the U.S., except for Australia where locally developed technologies 

using spirally-wound poly vinyl chloride (PVC) profiles (i.e., Rib-Loc) have the major market share. In 

other countries, there are more individual projects rather than consistent, everyday markets for both 

conventional (open trench) and trenchless methods. In a few countries (e.g., China, India, Russia), the 

market appears to be poised for a rapid development into large and sustained markets. 

The current rehabilitation market for wastewater is almost entirely in gravity sewers and laterals. 

Rehabilitation of force mains remains a small market with occasional projects, rather than being a 

consistent, everyday market. This is the case both in the U.S. and abroad. 

The rehabilitation of drinking water distribution systems is an emerging market in the U.S. and abroad. 

An exception is the U.K., primarily due to privatization of the water utilities in the early 1990s, which 

resulted in an accelerated adaptation of new rehabilitation methods. This is not to say that the needs for 

water rehabilitation are small. As presented in the report Dawn of the Replacement Era: Reinvesting in 

Drinking Water Infrastructure (American Water Works Association [AWWA], 2001a): 

“For the first time, in many of these utilities a significant amount of buried 

infrastructure—the underground pipes that make safe water available at the turn of a 

tap—is at or very near the end of its expected life span. The pipes laid down at different 

times in our history have different life expectancies, and thousands of miles of pipes that 

were buried over 100 or more years ago will need to be replaced in the next 30 years. 

Most utilities have not faced the need to replace huge amounts of this infrastructure 

because it was too young. Today a new age has arrived. We stand at the dawn of the 

replacement era. Extrapolating from our analysis of 20 utilities, we project that 

expenditures on the order of $250 billion over 30 years might be required nationwide for 

the replacement of wornout drinking water pipes and associated structures (valves, 

fittings, etc). This figure does not include wastewater infrastructure or the cost of new 

drinking water standards. Moreover, the requirement hits different utilities at different 

times and many utilities will need to accelerate their investment. Some will see rapidly 

escalating infrastructure expenditure needs in the next 10–20 years. Others will find their 

investment decisions subject to a variety of factors that cause replacement to occur 

sooner or at greater expense, such as urban redevelopment, modernization, coordination 

with other city construction, increasing pipe size, and other factors.” 

These massive financial needs were also reported by EPA, which estimated that $183.6 billion should be 

invested by 2023 into distribution and transmission infrastructure (pipelines) (EPA, 2003). Estimates of 

need have escalated since these figures were published due to the increased worldwide demand for key 

raw materials such as ductile iron, copper, and plastic feedstocks. 

3
 
 

1.4 History of Wastewater Rehabilitation 

Until the 1970s, any rehabilitation of sewers was limited to man-entry pipes (>36 inches), and the works 

were comprised mainly of local in-situ repair of damaged sections such as mortar in brick sewers. 

Smaller sewers or man-entry sewers with more extensive problems were simply replaced in open trench 

works. Moreover, there were no economic, social, or managerial drivers for sewer rehabilitation 

programs and such work was unlikely to take place unless collapses had occurred. 

However, such collapses and the associated disruption and loss of service became more frequent in the 

1960s and 1970s – especially in the U.K. and other Western European countries where the sewerage 

infrastructure is the oldest. The first cured-in-place pipe (CIPP) lining of a sewer took place in Brick 

Lane in Hackney, London, in 1971 for the Greater London Council Sewer Department. 

This developed into the Insituform System that remains a market leader to this day. As this technique 

began to penetrate the market, similar systems were developed in competition. However, the market 

remained small, limited to North America and Western Europe. 

On the expiration of Insituform’s U.S. patents for the lining and inversion process in 1994, there was a 

rapid and large increase in the range of available systems; this increased competition led to lower prices 

and increased cost-effectiveness, and a concomitant increase in market volume. Concurrently, public and 

political interest in maintaining the wastewater infrastructure more efficiently in order to protect public 

health and the environment created a strong regulatory driver for the market. This was especially the case 

in the U.S., where EPA began to enforce the Clean Water Act of 1972 more strongly with respect to 

sewer system overflows. Similar regulatory drivers began to apply in other countries in which an aging 

infrastructure is found together with high living standards and sophisticated political institutions. A 

continuing problem, however, is that the interactions remain poorly understood between pipe 

deterioration, wet weather peak flows, wastewater treatment processes, and improving the overall system 

performance in terms of human health and environmental protection. This lack of understanding can lead 

to less than optimal decision processes for capital investment and asset management of the overall 

wastewater infrastructure. 

1.5 State of Technology Review Report Organization 

Sections 2, 3, and 4 of the State of Technology Review Report discuss the key issues affecting the costeffectiveness and progress of rehabilitation efforts in the water and wastewater sectors. Section 2 

discusses issues common to both systems, and Sections 3 and 4 discuss wastewater and water systems 

individually. 

Section 5 examines the current state-of-practice for rehabilitation in the water and wastewater sectors and 

the potential for improvement within the general classes of rehabilitation systems. Section 6 identifies 

some emerging or novel technologies as candidates for potential demonstration. These technologies 

provided a starting point for discussion at the International Technology Forum. Section 7 discusses the 

organization of a demonstration program designed to help improve and speed the adoption of selected 

rehabilitation technologies. Section 8 provides a summary of key findings and recommendations from the 

Forum. 

Appendix A provides a glossary of acronyms used in the report. Appendices B, C, and D provide 

descriptions of rehabilitation technologies in both the wastewater and water sectors. Appendix E provides 

example quality control standards for rehabilitation. 

4
 
 

2.1 

2.0 COMMON ISSUES FOR REHABILITATION SYSTEMS 

In this section, key issues will be explored that cut across both water and wastewater applications and that 

apply to many of the specific technologies used for rehabilitation. Rehabilitation systems are already 

applied (field installed) widely with good success, but it is believed that improvements in certain areas 

will provide more consistent design approaches among methods, more competitive bidding and method 

selection processes, and better quality assurance and quality control (QA/QC) for these systems. 

Need for Rational and Common Design Approach for Rehabilitation Systems 

Most rehabilitation methods have been developed as proprietary systems; the standards for their design 

and use have been developed on a technique-by-technique basis, even though the design principles have 

many common elements. Many technical innovations start in this way with the design, construction, and 

many aspects of QC being provided by the company offering the technology. The downside to this 

approach is the potential lack of common safety factors among methods, the lack of control of design 

details by owners and their consultants, and the lack of a common playing field for comparison among 

methods. Over time, most proprietary technologies make a transition from this situation to one in which 

most aspects of the design process are handled by the design engineer working on behalf of the owner. 

The contractors then bid to a specific design, which may allow several different rehabilitation products to 

compete on a common performance basis. 

A second aspect of the evolution of design processes in most areas of engineering has been the shift from 

designs based on an allowable working stress (which includes a global safety factor) to designs based on 

determining the predicted load at failure and applying partial safety factors to the different aspects of the 

design process (e.g., loading, structural response, material strength, etc.) according to how accurately 

these elements are known and what their expected variations would be. This approach allows a consistent 

treatment for a variety of “limit states” (failure conditions), and the design can be checked that it satisfies 

all of the required limit states. With this approach it is also easier to compare the performance of different 

(but somewhat similar) systems on a common basis. 

For instance, the design of a cured-in-place (CIP) liner system for sewers currently follows the nonmandatory appendix of the American Society for Testing and Materials (ASTM) F-1216 standard. This 

standard describes the methodology of a CIP liner system and some QC standards to which the 

installation should adhere. In terms of structural design, the standard uses two loading mechanisms: one 

based on loading of the liner by external groundwater pressure and one based on the soil loading being 

applied to the liner through a “fully deteriorated” host pipe. Two design controls are used, namely the 

allowable levels of buckling and local bending stresses, but the application of partial safety factors for 

loadings or material strength/stiffness is not possible. There is no available methodology currently to 

develop the needed safety factors for CIPP as a function of installation method, curing process, 

geometrical imperfections, and other factors affecting the mechanical properties of the final product. 

Furthermore, if a CIP liner is to be used in a pressure pipe, a different ASTM standard (ASTM 2207-02) 

is used, and different combinations of loadings are considered. Thus, the key loading configurations and 

the structural response of the liner are addressed in a fragmented manner with no explicit considerations 

of the variations in safety factors against the different limit states. In addition, there is no rational method 

to assess the design life of liners that might not meet their original design criteria. In some cases, liners 

were found to have only 60 to 90 percent of the structural strength specified in the contract. 

Currently, there is no rational method to link between the reduced mechanical properties of the installed 

liner and the potential reduction in service life of the liner. A limit state design approach will provide a 

quantified approach for evaluating the effect of under-strength liners in terms of increased probability of 

5
 
2.2 

failure for specific failure mechanisms. The solution is to develop a limit state design approach for 

various lining categories. This approach requires the development of large experimental databases. 

Currently the Trenchless Technology Center (TTC) at Louisiana Tech University is developing a limit 

state design approach for CIP liners. Data were collected from 600 buckling tests conducted by 

universities and companies around the world over the past 20 years. The data are currently subjected to a 

rigorous statistical analysis to statistically derive the needed limit state coefficients. 

QA/QC Procedures for Rehabilitation Technologies 

To take full advantage of the estimated design life of the various trenchless rehabilitation technologies, it 

is important that the installer uses proper installation controls and that the finished quality is confirmed by 

good assurance protocols and/or testing. Qualification (i.e., proof of design) testing is typically 

performed on the materials and the related installation process to define applicability of a particular 

technology. The installation process is given control limits by the technology manufacturer that allows 

the installer to pre-judge the finished quality of the installation during the execution of the work and prior 

to acceptance testing by the owner. QA and acceptance testing confirm that the installation is consistent 

with the product that was pre-qualified in the design phase and that it should live up to its design 

performance expectations. 

The design approach must be supported by the systems’ qualification type or testing. Depending upon the 

technology being used, the level of the rehabilitation system’s qualification testing varies greatly in the 

trenchless rehabilitation industry. For instance, the evaluation and testing of the materials for CIPP are 

given by the requirements of ASTM Standard D5813, Standard Specification for Cured-In-Place 

Thermosetting Resin Sewer Piping Systems. This standard used in conjunction with one of the many 

installation method standards (such as F1216, F1743, and F2019) presents a very clear statement of the 

CIPP system to be used – its range of applications, its environmental performance capabilities, its proper 

installation, and its proper finished performance properties. Fold and Form thermoplastic PVC piping 

rehabilitation systems do not have such a qualification standard; they do, however, have a material 

specification and an installation standard. These "proprietary" standards, however, don't address the 

qualification testing of the stated cell classes for service in the application of lining pipe; further, there is 

no long-term performance verification testing required for these thermoplastic materials after going 

through the known rigors of the deformation/reformation process. Similarly, other material specifications 

and installation standards are used for high density polyethylene (HDPE) rehabilitation systems (e.g., pipe 

bursting, sliplining, etc.) and for grouted-in-place lining (GIPL) systems and structural panels. The lack 

of long-term validation is cited as one of the impediments to using rehabilitation technologies in general. 

For CIPP, ASTM D5813 serves as an industry qualification standard, addressing the demonstration of 

long-term performance of the finished product in an aqueous environment that includes various chemical 

solutions likely to be found in the sewer or water environment by subjecting the CIPP samples to a 

battery of tests lasting 10,000 hours in length. The materials are tested for both strain corrosion and 

chemical corrosion in these hypothetical environments to project performance in service of 50 years (or 

more). Material systems certified to having been subjected to the testing contained within this standard 

give the design engineer and system owner the necessary information to make an informed selection for 

the application under consideration. The standard looks at both the load case classification (Type I, II, or 

III) and the grade of CIPP required (Grade 1, 2, or 3). The Type I loading condition is a relatively thin 

lining that prevents exfiltration and provides chemical resistance. The Type II loading condition prevents 

infiltration as well as exfiltration (thus, it has to be capable of supporting the external hydrostatic load) 

and provides chemical resistance; this is the F1216 partially deteriorated design condition. The Type III 

loading condition is the ASTM F1216 fully deteriorated load condition, which is expected to bear all 

loads placed upon the host pipe. Grade 1, 2, and 3 refer to the resin system used, i.e., polyester, vinyl 

ester, and epoxy, respectively. 

6
 
 

 

For other lining systems, the suitability of the liner material and the installation process for a particular 

application must be determined by broadly applicable testing standards for the materials used and/or 

proprietary testing carried out by the manufacturer for the pipe lining system. Depending on the materials 

and the application, this combination may result in a very clear and consistent QA/QC approach or it may 

leave gaps in the QA/QC coverage for particular applications. 

QC procedures for the various technologies discussed herein are typically given to the installation 

contractor by the system manufacturer. To further reinforce a system’s commitment to having a quality 

installation, the manufacturers will develop an ASTM installation standard for their system. Appendix E 

provides examples of the current extent of coverage of industry-wide standards for rehabilitation systems. 

QA is the responsibility of the system owner or the designated project engineer. Whether utilizing 

prescriptive or performance specifications, it is important that this communication with the installer 

convey what QA testing will be performed, and then the contract documents need to follow through on 

this testing. Too often, trenchless technologies have specifications for reasonable assurance testing, but 

those overseeing the project do not perform the testing. Samples of the finished installation need to be 

taken to confirm that the minimum mechanical properties have been achieved or have gone unaltered. Fit 

and finish should be evaluated in light of the prior condition of the host pipe and the system being 

installed. It is generally preferable that the relationship with the testing laboratory providing the results of 

the testing resides between the owner and the laboratory; not the contractor and the laboratory. 

Current QA testing has its drawbacks. Most CIPP projects require restrained samples to be taken from 

cured liners where the liner is inflated in a pipe sleeve of like diameter either at an intermediate manhole 

or the receiving end manhole so that the approximate thickness of the liner during installation after the 

rigors of its placement can be captured to provide determination of the as-built mechanical properties of 

the newly installed CIPP. These samples must be properly taken to provide an accurate representation of 

what is in the ground. They must rest horizontally, with a sufficient heat sink, to simulate the ground 

during the curing process. The restrained samples are taken in manholes or other access locations and 

thus the heat loss and/or moderation provided by the host pipe and pipe embedment materials must be 

replicated by placing a “soil envelope” on the sample tube. Often this is not achievable due to the size 

and shape of the receiving manhole. Currently there is a change before the ASTM F17.67 sub-committee 

to add ultrasonic thickness testing as an alternative to using the thicknesses derived from the restrained 

sample. A method of non-destructive determination of the finished mechanical properties also is lacking. 

Ultra-wideband pulsed radar systems, ultrasonic measurements, and before-and-after laser profiling are 

potential methods to provide definitive finished thickness information. However, none of these methods 

is fully developed for in-pipe liner thickness measurements. 

Water-tightness is another issue confronting trenchless rehabilitation technologies. CIPP, which is seen 

as a monolithic structure, from time to time has “leaks through the wall.” Joints in just installed 

thermoplastic panel systems have leaks, especially when machine installed in non man-entry size piping. 

One question that should be resolved is how leakage testing should be carried out and what level of 

leakage is acceptable, both from a life-cycle view of the installation and an inflow and infiltration (I&I) 

perspective. Some recent inspection systems (e.g., the FELL electro-scan system) provide an effective 

means of finding and quantifying leaks and, perhaps more importantly, potential leaks that are not 

currently active – but only in nonconductive pipe systems. 

As the governing patents expire on many aspects of rehabilitation technologies, more companies are 

encouraged to enter the marketplace and compete with the established technology providers. This 

provides increased competition – leading in general to lower prices – but it also may provide an incentive 

to cut corners on QC as part of the price competition. Also, new entrants into the rehabilitation 

marketplace may not have as well developed technical “know how” (staff education level and 

7
 
2.3 

experience). This means that systems that have gone through their learning curve and become highly 

reliable techniques may exhibit a more variable performance as the marketplace widens. When, and if, 

this happens, it is important that QA/QC procedures are in place and used effectively – both to provide a 

high performance and long-lived product and allow contractors who provide quality to compete fairly 

with those willing to cut corners to win jobs at a lower cost. 

In summary, better QA/QC-related technologies and procedures are an important part of providing 

improved technologies for water and wastewater system rehabilitation, especially as the governing patents 

expire and proprietary systems become commodity products. 

Decision Support for Choice of Rehabilitation vs. Replacement and Choice of 

Rehabilitation Systems 

Even with a comprehensive set of fully effective rehabilitation technologies, many issues would still 

remain about how and when to apply the technologies. According to an EPA report (2007a), “System 

rehabilitation is the application of infrastructure repair, renewal, and replacement technologies in an effort 

to return functionality to a drinking water distribution system or a wastewater collection system.” The 

circumstances that affect rehabilitation planning and prioritization include the current condition of the 

system, the extent of critical repair needs, the availability of funding for rehabilitation work, and the 

ability to inspect and assess the condition and deterioration rate of each element of the system. The broad 

activities that determine system-wide planning follow asset management principles and life cycle analyses 

that are being increasingly employed in water and wastewater systems in the U.S. These principles mean 

that rehabilitation approaches may include partial rehabilitations to extend performance life as well as full 

structural rehabilitations to reset the life cycle performance clock. Which one is most appropriate and 

cost effective depends on the deterioration rate of the asset, the ability of the rehabilitation method to 

extend performance life, and the cost and social/environmental impact of the method against competing 

approaches. Unfortunately, most of these parameters are poorly understood and require a significant 

commitment to ongoing inspection and condition assessment within a system before accurate quantitative 

behavior parameters can be established. The issues relating to condition assessment and system-wide 

asset management are being addressed under separate task orders within the EPA program. There remain 

several issues that apply directly to the selection of rehabilitation methods that have a strong bearing on 

the cost effectiveness of rehabilitation programs and their impact on traffic and environment in the areas 

where the rehabilitation work is needed. 

The key decision needs are to determine: 

	 Whether to renovate or replace (via trenchless or open-cut construction methods) water 

and wastewater pipes 

	 Which of the commercially available rehabilitation methods are suitable for a particular 

application 

Open-cut replacement has been the standard practice in the past, but its preferential use over trenchless 

techniques has been significantly diminished in the past two decades – particularly in the wastewater 

sector. Awareness of the indirect and social costs associated with utility work in congested urban areas 

(i.e., traffic congestion, loss of pavement life, business impacts, noise, and dust) have encouraged the use 

of “full” costing approaches in determining the choice between open-cut replacement and trenchless 

rehabilitation or replacement methods. Often, however, the choice of trenchless technologies is driven by 

acknowledged environmental constraints and expected public pressure rather than by a quantitative 

calculation of full direct, indirect, and social costs. Also, differences in social and indirect impacts are 

often addressed in work requirements that reduce or eliminate any cost advantage to open cut in 

8
 
congested or sensitive settings. Such work requirements may include payment for traffic lanes occupied 

(i.e., A+B bidding method [Gilchrist and Allouche, 2005]), restrictions on work hours, noise barriers, 

plating of excavations for traffic flow during peak periods, remote storage of excavated materials, 

reimbursement for business loss and damage to adjacent utilities. The awareness of the issues and the 

adjustment of working practices have had a significant impact in the wastewater sector where the typical 

positioning of mainline services (large diameter, deep, and in the center of streets) makes their 

replacement an operation involving major disturbance and cost. In the water sector, distribution pipes are 

typically of smaller diameter, shallower and may be at the edge of or behind roadway curbs. But 

technical difficulties arise in providing a pressure-tight rehabilitation system including the connections of 

the relined mains to the service lines. This has traditionally required open-cut excavation at connections, 

which negates some of the benefit of trenchless rehabilitation technologies and has kept the penetration of 

water main rehabilitation approaches slower than that for sewers. 

Selection of trenchless rehabilitation approaches involves a screening process followed by a more detailed 

evaluation of the technologies. It is generally easy to exclude some technologies as evidently not suitable 

for a particular application. The remaining technologies may be generally suitable but have different cost, 

risk, setup area requirements, life cycle performance, compatible materials and environmental impacts. A 

new element in these considerations is how “green” a product or process is. For example, many 

trenchless methods have a much lower carbon footprint than open-cut repairs. Evaluation of technology 

differences in a rational and impartial manner is a persistent but important challenge. Specifying a single 

technology in request for proposals may have a negative impact on the competitiveness of bids received 

for the use of that technology. Ideally, a level playing field is created when bidders can propose one of 

several suitable technologies, so that a fair competition is created with similar performance characteristics 

specified for each technology. 

2.4 Special Applications 

There is a wide range of rehabilitation needs within water distribution and sewer collection systems. 

These needs include rehabilitation of various types of gravity and pressure piping systems and 

rehabilitation of a wide variety of ancillary structures such as manholes, valve chambers, pumps and lift 

stations. The most common situations are well provided for in terms of technologies, materials, and 

design approaches – with some room for improvement in QA/QC approaches. However, certain special 

application conditions are not well provided for, either in terms of suitable materials or design and 

QA/QC approaches. Two particular areas are described below as examples of this issue. 

2.4.1 Elevated Temperature Liner Service Conditions. The City of New York has extremely 

congested utility conditions beneath its streets and the range of installed utilities includes steam lines, 

often running in close proximity to sewer lines. Rehabilitation of the sewer lines is urgently needed; but 

as a deeply-placed utility, open-cut access from the surface is prohibitive in terms of cost and impact on 

traffic. Trenchless rehabilitation of the sewer lines is a very desirable option, but a complicating factor is 

that the steam lines have condensate traps, leaks and venting systems that discharge condensate and/or 

steam (~220 °F) into the sewers. The high temperature provides a very challenging environment that 

cannot be met by the current thermoplastic or thermosetting lining materials available in the marketplace. 

In addition, the temperature differential between the head section of the pipe (which is filled with steam at 

220 °F) and the invert of the pipe (covered with water at 40 °F) results in differential strain and unique 

loading mechanisms (i.e., limit states) not encountered in common applications. Currently, a search for 

suitable materials and their testing to confirm applicability under the anticipated service conditions is 

being funded jointly by the City of New York and Consolidated Edison Company of New York (Allouche 

et al., 2009). It is worth mentioning that this problem is common to some older cities in the U.S. that 

operate similar thermal energy systems including Boston, Philadelphia, Harrisburg, Milwaukee, and 

Seattle. In addition to solving this particular class of problems, the research will open a range of new 

9
 
applications for rehabilitation under similar challenging conditions in industrial or power plant 

applications. 

2.4.2 Relining of High Pressure Piping Systems. Rehabilitation systems are available in 

considerable variety for pressure pipe applications, but most have been designed to handle the pressure 

levels commonly experienced in water distribution systems. However, there are other applications where 

high pressure pipelines need to be rehabilitated and for which adequate test data on liner approaches and 

suitable composite materials do not yet exist. Liners can be designed either as stand-alone replacements 

for the host pipe, or as “semi-structural” liners that rely on the host pipe for overall structural stability but 

provide a bridging capability across holes, cracks, and failing joints. The materials used to provide the 

higher pressure capacity often do not have the same ability to conform easily to the host pipe, which can 

create ridges in the liners. Poor cleaning of the host pipe prior to lining also can create local deformations 

in the liner. Both kinds of defects can act as stress raisers within the liner and lower the pressure rating of 

the liner. To address this problem, it is necessary to gain a fuller understanding of types of defects in 

pressure liners and better understand their impact on liner performance. This is particularly true for a new 

class of organic “high-build” coating systems such as polyurea and 100 percent solid polyurethane. These 

products, which are able to be built to thicknesses of 2 inches within seconds and a pressure rating 

exceeding 1,000 psi, provide new opportunities to the pipeline rehabilitation industry (Johnson et al., 

2002) but require the appropriate qualification and service testing for pressure pipe applications. The 

procedures for ongoing maintenance, installation of new services, and emergency repairs of rehabilitated 

pipe sections also are a key concern. This issue is addressed later in Section 4.1.9. 

10
 
 

3.1 

3.0 WASTEWATER SYSTEM ISSUES 

In this section, the issues relating to rehabilitation of wastewater systems will be examined in more detail. 

The water system rehabilitation issues are addressed in Section 4. 

System Characteristics 

The U.S. sewer network totals approximately 800,000 miles in length. Force mains comprise 

approximately 7.5 percent; thus, the force main system is approximately 60,000 miles and the gravity 

network is approximately 740,000 miles. An estimated 25 percent of the gravity sewer network is more 

than 40 years old, 77 percent is 12 inches in diameter or smaller, and 44 percent is clay or concrete pipe 

(Water Environment Research Foundation [WERF], 2004). Tables 1 and 2 provide a percentage 

distribution of pipe material types within various pipe size ranges for gravity sewers and force mains, 

respectively (WERF, 2004). 

The force main network is not as old as the rest of the sewer network – about 2 percent is greater than 50 

years old, while 68 percent is less than 25 years old (WERF, 2008). 

The American Society of Civil Engineers (ASCE) gave wastewater infrastructure a grade of D- in its 2007 

annual report card (ASCE, 2007). This was the lowest grade given for any infrastructure category. This 

is despite the replacement or rehabilitation of approximately 8,000 miles of sewers annually at a cost of 

some $4.5 billion per year. The system is aging, in many cases well beyond its design life; as a result, it 

is no longer serviceable at an adequate level. There are also huge differences among different 

municipalities with some having created a very effective rehabilitation program and some doing little or 

nothing in terms of system rehabilitation. 

Table 1. Gravity Sewer Systems: Percent Distribution by Pipe Material and Diameter Range 

(WERF, 2004) 

Material 

Diameter, inches 

4 to 12 14 to 20 21 to 36 37 to 54 ≥ 60 

VCP 41 36 23 7.1 3 

RCP 18 28 44 64 63 

Lined RCP 1.4 3.9 6.2 17 20 

PVC 27 15 6 1.6 0 

HDPE 1.5 1.4 1 0.9 0 

DI/CI 8.6 12 10 4.1 2.5 

ACP 3.8 2.6 1.3 5.1 0.1 

Brick 0.5 0.9 2.1 3.8 4.2 

Other 0.9 1 3 0 6 

Notes: VCP = vitrified clay pipe; RCP = reinforced concrete pipe; PVC = poly vinyl chloride; HDPE = 

high density polyethylene; DI = ductile iron (lined and unlined); CI = cast iron (lined and unlined); ACP 

= asbestos cement pipe. 

11
 
Table 2. Force Main Systems: Percent Distribution by Pipe Materials and Diameter Ranges 

(WERF, 2008) 

Material 

Diameter, inches 

4 to 12 14 to 20 21 to 36 37 to 54 >54 

DI 46.8 62.5 46.0 13.9 3.1 

CI 16.9 12.7 5.3 <0.1 0 

PVC 28.4 3.5 0.9 0.1 0 

HDPE 2.0 1.0 0.2 0 0 

PCCP/CCP 1.0 3.1 26.1 54.6 58.1 

Steel 0.5 2.0 10.4 12.9 30.4 

FRP 0 0.1 0 0 0 

ACP 4.0 12.2 0.7 5.0 0 

RCP <0.1 2.5 10.4 13.4 8.4 

Other/not known 0.4 0.5 0.1 0 <0.1 

Notes: DI = ductile iron; CI = cast iron; PVC = poly vinyl chloride; PCCP/CCP = prestressed 

concrete cylinder pipe/concrete cylinder pipe; FRP = fiberglass reinforced pipe; ACP = asbestos 

cement pipe; RCP = reinforced concrete pipe. 

3.2 Drivers for Increased Rehabilitation Efforts 

The driver of almost all sewer rehabilitation works in the U.S. is the system of fines and consent decrees 

imposed by EPA. These generally refer to sanitary sewer overflows (SSOs) and combined sewer 

overflows (CSOs) in both gravity sewers and force mains. The regulatory system has a variety of 

elements, and there is a degree of overlap, even contradiction, among them. Greater coordination of the 

various programs may enable more efficient allocation of resources to achieve the overriding objectives 

of protecting public health and the environment. 

3.2.1 National Pollutant Discharge Elimination System (NPDES). The NPDES permit program 

controls water pollution by regulating point sources (e.g., collection systems and treatment plants) that 

discharge pollutants into open waters. The NPDES is part of the 1972 Clean Water Act intended to 

protect the country’s waters and directs EPA to issue rules on implementation. Industrial, municipal, and 

other facilities must obtain permits if their discharges go directly to surface waters. In most cases, the 

NPDES permit program is administered by individual states. 

3.2.2 Sanitary Sewer Overflows (SSOs). EPA estimates that $88 billion is needed over the next 

20 years to control SSOs and that this figure may be even higher if the Agency continues to take a zero 

tolerance stance on SSOs. Municipalities have made significant progress in improving water quality 

since the implementation of the Clean Water Act, but the wet weather arena demands a more consistent 

regulatory and enforcement framework, specifically relating to SSOs. Proposals have been made, e.g., by 

the National Association of Clean Water Agencies (NACWA) that a national SSO policy should 

recognize the level of risk posed by SSOs nationally and be modeled after EPA’s CSO Control Policy to 

provide the flexibility necessary to address adverse impacts when manifested at a local level and to direct 

resources to those areas that will have the most impact (NACWA, 2007). 

3.2.3 Combined Sewer Overflows (CSOs). EPA’s CSC Control Policy is a national framework 

for control of CSOs through the NPDES permitting program (Federal Register, 1994). The Policy 

provides guidance to municipalities and State and Federal permitting authorities on how to meet the Clean 

Water Act’s pollution control goals as flexibly and cost-effectively as possible. 

12
 
 

The Policy contains four fundamental principles to ensure that CSO controls are cost-effective and meet 

local environmental objectives: 

(1) Clear levels of control to meet health and environmental objectives. 

(2) Flexibility to consider the site-specific nature of CSOs and find the most cost-effective 

way to control them. 

(3) Phased implementation of CSO controls to accommodate a community’s financial 

capability. 

(4) Review and revision of water quality standards during the development of CSO control 

plans to reflect the site-specific wet weather impacts of CSOs. 

CSO communities have made significant progress in reducing the frequency and size of overflows, but 

more work remains to be done. EPA estimates that the annual CSO volume is approximately 850 billion 

gallons, down from over 1 trillion gallons prior to issuance of the 1994 CSO Control Policy. EPA also 

estimates that approximately $51 billion is still needed over the next 20 years to meet the goals of the 

policy (NACWA, 2007). 

3.2.4 Capacity, Management, Operation, and Maintenance (CMOM) Program. The CMOM 

regulations are part of the SSO regulations affecting some 19,000 sanitary sewer collection systems 

throughout the country. Owners of all municipal wastewater collection systems are required to develop 

procedures to improve system capacity, perform long-term planning for investments in infrastructure, 

develop better documentation and asset management procedures, and share all of this information with 

stakeholders more effectively. The CMOM is derived from a need for reducing sewer overflows and the 

consequent health risks associated with these overflows. The purpose of the CMOM approach is to abate 

SSOs, reduce health risks, extend the life of sewer system assets, and improve utility customer 

satisfaction. 

3.2.5 Government Accounting Standards Board (GASB) Statement No. 34. The GASB, a nongovernment entity that defines the criteria that auditors use to judge the adequacy of local and state 

government financial statements, has changed long-standing practices by requiring that government 

entities include reporting of their capital assets in their annual balance sheet and income statement. 

GASB-34, adopted in June 1999, highlights the costs of acquiring, owning, operating, and maintaining 

public-works infrastructure for government-bond holders and the public at large. GASB-34 requires that 

the value of infrastructure assets be shown on the balance sheet, and gives governments a choice of 

adopting either (a) traditional private-sector methods of calculating infrastructure depreciation expenses 

based on historical acquisition costs, or (b) an effective asset management system. These asset 

management systems must demonstrate either that maintenance spending is adequate to prevent 

infrastructure deterioration or that infrastructure condition is being maintained at or above explicitly 

stated minimum acceptable standards. 

3.2.6 Rehabilitation Funding. Federal funding under the Clean Water Act State Revolving Fund 

(SRF) program has remained flat for the past decade. Congress appropriated between $1.2 billion and 

$1.35 billion annually from 1995 to 2004. However, in FY 2005, Congress cut wastewater SRF funding 

for the first time in eight years, reducing the total investment to $1.1 billion. The administration proposed 

further cuts for FY 2006 and 2007, with a budget submittal calling for an appropriation of only $688 

million in FY 2007, a reduction of 37 percent from the FY 2005-enacted level. In March 2007, the U.S. 

House of Representatives approved the Water Quality Financing Act, 2007, which reauthorized the Clean 

Water SRF at $14 billion over 4 years (FY 2008 to 2012). 

13
 
 

 

 

Funding for sewer renovation and maintenance is a major challenge for municipalities throughout the 

country. The sources of funding are grants, local taxes (rates), or debt (bond) issues. All are limited in 

amount and are politically sensitive at a local and national level. The competition for funds within 

municipal budgets is intense, and the budgets themselves are constantly under scrutiny, irrespective of 

economic conditions. The current economic downturn serves to increase this budgetary pressure; many 

cities have cut budgets for sewer inspection, maintenance, and renewal. 

As a result, municipalities are caught between increasing regulatory demands and lack of adequate funds 

to meet those demands. Solving this issue requires innovative and visionary thinking in terms of asset 

management along the lines dictated by GASB-34, but there has been little adoption of this approach in 

the U.S. Political time horizons, dictated by electoral cycles, militate against implementation of asset 

management solutions that show benefits over a longer period. 

The silver lining is that the need to do more with less creates opportunities for innovation in technology, 

organization, business processes, and management that will optimize resource allocation in order to 

achieve the regulatory objectives as efficiently as possible. 

3.3 Problems Typically Encountered in Wastewater Pipe Systems 

In searching for the most effective rehabilitation approaches, it is important to understand the most 

frequent types of defects that are present in wastewater pipe systems. These vary by the type of pipe 

system and by the type of pipe material used. It has been found that defects may vary by period of 

installation due either to variations in material quality (e.g., thick wall versus thin wall cast iron pipes) or 

QC and work crew issues (e.g., quality of bedding and backfill control). 

3.3.1 Gravity Sewers. Table 3 provides a summary of frequently observed distress in gravity 

sewer systems (WERF, 2004). Based on survey data on the types of defects observed and taking into 

consideration the frequency of use of the pipe materials, the priority ranking for problems affecting 

gravity sewers has been assessed as: 

 Cracks 

 Internal corrosion 

 Grease build-up (plus grit and debris) 

 Root intrusion 

 Joint misalignment/separation/leakage 

 Excessive pipe deflection 

 Lateral connection/leakage 

 Grade and alignment. 

These problems can cause either partial blockages leading to backing-up and overflows upstream, or 

excessive infiltration leading to surcharge and overflows downstream. 

3.3.2 Laterals. As municipalities have worked to rehabilitate their mainline networks using 

relining or replacement approaches, it has become evident in many cases that the savings in inflow and 

infiltration (I&I) expected from the rehabilitation work have not always occurred. 

The probable cause of the low achievement of I&I reductions has been identified in many cases to be the 

problems with the private sewer connections to the mainline sewers in the streets (private lateral sewers or 

“laterals”) (WERF, 2006). While the mainline sewers in most cases need urgent attention, the omission 

of the laterals from the rehabilitation programs results in an incomplete solution. The problem is 

14
 
Table 3. Main Defects in Gravity Sewer Systems by Sewer Material 

Material Potential Problem/Defect 

Vitrified Clay 

 Cracks/broken pipe 

 Root intrusion 

 Grease build-up 

 Joint misalignment and/or leakage 

PVC 

 Excessive deflection 

 Grease build-up 

 Joint misalignment and/or leakage 

 Grade and/or alignment 

 Lateral connections 

Concrete 

 Internal or external corrosion of concrete and/or reinforcement 

 Cracks and fractures 

 Grease build-up 

 Joint misalignment and/or leakage 

 Root intrusion 

 Missing wall sections 

 Open joints 

Cast Iron/Ductile Iron 

 Internal corrosion 

 External (pit) corrosion 

 Circumferential breaks 

 Grease build-up 

 Joint failure and/or leakage 

 External corrosion 

 Longitudinal break/split 

 Corporation cock failure 

 Leaking laterals 

Concrete with Liner 

 External corrosion of concrete and/or reinforcement 

 Liner failure or separation (including weld failure) (leading to internal 

corrosion) 

 Grease build-up 

 Root intrusion 

 Cracks 

 Joint misalignment and/or leakage 

 Capacity 

Prestressed Concrete Cylinder Pipe / 

Concrete Cylinder Pipe 

 Corrosion of prestressing wires 

 Grease build-up 

 Root intrusion 

 External corrosion 

 Joint leakage 

 Internal corrosion 

 Pressure capacity 

Polyethylene 

 Excessive deflection 

 Grease build-up 

 Root intrusion 

 Grade and alignment 

 Leaking laterals 

Pressure Only  Pressure capability 

15
 
Table 3. Main Defects in Gravity Sewer Systems by Sewer Material (Continued) 

Material Potential Problem/Defect 

Steel 

 Internal corrosion 

 Weld failure 

 External (pit) corrosion 

 Excessive deflection 

 Joint leakage 

 Stress fractures 

Brick 

 Missing bricks 

 Soft mortar 

 Vertical deflection and collapse 

 Cracks 

 Grease build-up 

 Root intrusion 

Asbestos-Cement 

 Internal corrosion 

 Cracks 

 Grease build-up 

 Root intrusion 

 Joint misalignment and/or leakage 

Fiberglass 

 Grease build-up 

 Excessive deflection 

 Root intrusion 

 Cracks/delamination 

particularly acute under conditions where the sealing of the mainline causes the groundwater table to rise 

sufficiently to increase the flows into the cracked and leaky laterals – thus circumventing (at least partly) 

the sealing of the mainline. When projected savings from expensive rehabilitation projects fall short, 

political questions are raised about the value of such work. In some cases, funding for rehabilitation work 

has been suspended. 

The topic of when and how to address the rehabilitation of private sewer laterals was the subject of a 

project funded by WERF and carried out by TTC at Louisiana Tech University between 2003 and 2005 

(WERF, 2006). 

Ownership of sewer laterals varies significantly for municipalities even within a single metropolitan area. 

As shown in Figure 1 (WERF, 2006), most commonly, the private property owner owns the lateral sewer 

all the way to the sewer main in the street (55.2 percent in the referenced survey), but there is a split as to 

who owns the actual connection into the main (often called a sewer “tap”). A smaller percentage (43.1 

percent) of property owners owns the lateral only to the property line. There is also a significant 

difference of opinion as to whether cleanouts should be installed at the private property line. Where 

cleanouts are installed, these often serve as the demarcation of private and public ownership, but not in all 

cases. Cleanouts do help greatly with some types of rehabilitation, can assist in maintenance, and also 

make it easier to determine whether the private or the public section of a lateral is causing the I&I 

problem. 

16
 
9 agencies (15.5% ) 23 agencies (39.7%)

1 agency (1.7%)

25 agencies (43.1%)

From house to property line

Definition varies

within same agency

From house to mainline

excluding tap

From house to mainline

including tap

9 agencies (15.5% ) 23 agencies (39.7%)

1 agency (1.7%) 

25 agencies (43.1%) 

From house to property line 

Definition varies 

within same agency 

From house to mainline 

excluding tap 

From house to mainline 

including tap 

Figure 1. Private Ownership of Sewer Laterals (WERF, 2006) 

Even when municipalities conclude that their sewer laterals present a problem that should be addressed in 

a systematic fashion, there is often a reluctance to move ahead. Dealing with private property owners 

over sewer lateral repair is a difficult issue. Since most private property owners have no idea of the 

condition of their sewers, they will see little or no direct benefit from the repair; and the rehabilitation 

costs are usually significant. Linked to the legal issues of who owns which portion of the lateral, who 

should pay, etc. are also questions of legal right of access to the private property for inspection and repair 

work and legal liability for accidents during inspection or repair work. As with the issue of laterals 

ownership, there are many ways in which this is currently handled as well as many opinions on how it 

should be handled in the future. Some key issues/options regarding legal and liability matters are: 

	 Some states prohibit spending public money for private gain (i.e., improving private 

property by paying for rehabilitation of private laterals). This issue has been addressed 

successfully in the courts by arguing that the private gain is only incidental to a larger 

public gain from the reduction in sewer overflows and from savings in sewage treatment 

costs. 

	 Many municipalities consider taking any additional responsibility for private sewer 

laterals as a major concern in terms of additional work and public liaison. Other 

municipalities are more proactive – seeing themselves as being in the best position to do 

something about lateral problems by providing homeowner-friendly programs even if 

they do not take financial responsibility for the work. 

	 Gaining the political will to force homeowners to comply is often an issue with elected 

city councils who have to approve the program. 

Dealing with sewer laterals in a comprehensive manner can be an expensive undertaking, both for a 

municipality and for the private property owners involved. The first step is to determine whether a 

laterals program is justified from the cost-effectiveness perspective, although it can also be argued that a 

tight and properly functioning sewer system is not just a question of cost-effectiveness of treatment 

savings versus rehabilitation costs, but that it is required for a good, healthy urban environment. A first 

17
 
 

 

step is usually to examine and remove illegal connections of gutters and sumps into the sanitary sewer 

since these are often the most cost effective initial options. Programs can be much more successful with 

less public resistance if the financial aspects as well as the legal aspect are given close consideration. 

Some issues and approaches are listed below: 

	 For wealthier neighborhoods, financing options can be used to make it easy for the 

homeowner to say yes and proceed with the repair. For low-income neighborhoods, 

some kind of financial assistance or deferral of payment until property sale may be 

essential to allow a program to proceed. 

	 A few cities have decided that sewer lateral repair provides enough public good that they 

have put up all the money for such programs. 

	 Other cities use a warranty or insurance program approach where the homeowner 

essentially pays an insurance premium against the cost of a malfunctioning sewer system. 

	 Using a mandatory inspection at time of sale and a requirement to have the lateral in 

proper condition before the property is transferred allows the cost of lateral repair to be 

paid at a time when money is available from the property sale. This is true for both low 

income and wealthy neighborhoods. 

	 The city can use its program size to bid or negotiate uniform and low costs for the lateral 

repair. A homeowner can opt to bid the work themselves, but a quick check on an 

individual price can often convince the homeowner that joining the city program is an 

opportunity to take care of the problem at a lower price and with little effort on the 

homeowner’s part. 

3.3.3 Force Mains. Force mains that carry sewage flows under pressure represent a special set of 

challenges for sewer rehabilitation. As mentioned earlier, they represent approximately 7.5 percent of the 

system and typically use materials that are not used elsewhere in the sewer system such as steel, cast iron, 

and ductile iron. While siphons may be provided with redundancy for cleaning and inspection, most force 

mains do not have a bypass flow line and hence are difficult to take out of service for inspection or 

rehabilitation. The combination of corrosion potential, lack of inspection, and severe consequences for a 

failure make force mains a particular issue of concern. Figure 2 indicates the main causes of failure in 

ferrous and non-ferrous force mains. 

3.3.4 Pump Stations and Lift Stations. Pump stations are usually associated with force mains 

and are used where it is necessary to move the sewage flows against gravity for some distance. Lift 

stations are used where gravity sewage lines become too deep for economic installation and it is necessary 

to lift the sewage so that a new section of gravity sewer line can be installed at a shallower depth. The 

changing economics of deep sewer installation using microtunneling or directional drilling can make it 

possible to eliminate some lift stations either during construction of a new system or as a retrofit measure. 

This can have a significant impact on maintenance and rehabilitation needs for these ancillary structures. 

The focus of this report is on the rehabilitation of pipes and structures and hence the issues concerning 

pump maintenance and replacement schedules are not addressed in detail. It should be noted, however, 

that pump stations can “age” pipe through surge stresses. For the non-flow areas of pump and lift 

stations, normal structural rehabilitation issues will apply. The structures are often below ground and 

may suffer from some groundwater leakage into the structure and condensation during humid weather. 

Under damp and humid conditions, steel supports and frames may become corroded and equipment may 

gradually deteriorate. Rehabilitation typically involves working to eliminate the groundwater leakage, 

and providing new, easily maintained surfaces within the structure. Combinations of grouting, sealing, 

18
 
3rd Party Capacity Internal	 Damage 10% corrosion	 36% Joint 

27% Leakage 3rd party 3% damage
 

19%
 Surge 

Pressure 

7% 

External Corrosion 
 Joint
 27% corrosion 

leakage	 Structural 

Surge 19%

15% 27% 

pressure
 

10%
 

(a) Ferrous Force Mains (b) Nonferrous Force Mains 

Figure 2. Main Causes of Failure in Ferrous and Non-ferrous Force Mains 

and coating of interior walls are the typical approaches for such rehabilitation. Since the shape of the 

structures is often rectangular, it is not possible for liners to resist external groundwater pressure by 

arching action in curved sections; hence, most coating applications require the ability to bond to the 

existing structure. Further complicating the ability to seal such structures fully are the internal supports 

for equipment that may be bolted to internal walls and penetrations for venting to pass through the walls 

of the structure and any waterproofing or sealing layers. Providing a structure that is easy to maintain and 

keep dry is easiest during the initial design by: 

	 Keeping external and internal shapes as simple as possible for ease of construction and 

waterproofing. 

	 Avoiding sharp, re-entrant corners wherever waterproofing or sealing layers are to be 

applied. 

	 Ensuring that internal supporting members preferably slope slightly towards the wall of 

the structure so that leakage water will be kept adjacent to the wall. The same applies to 

the floor-to-wall junction. 

	 Providing an internal drain at the floor-wall junction for confining leakage issues and 

allowing easy collection and disposal of leakage. 

	 Carrying out an analysis of pump operations, maintenance, and emergency procedures 

during the design so that the facility can operate effectively and avoid damage to adjacent 

pipe sections. 

Wet well areas of lift and pump stations are subject to erosion and corrosion concerns, depending on the 

structural materials used and the level of hydrogen sulfide produced by turbulence in the wastewater flow. 

19
 
3.3.5 Drop Shafts. Drop shafts are used in wastewater systems to connect a shallow storm or 

sanitary sewer with a deeper sewer or interceptor tunnel system. Depending on the design of the drop 

shaft, the flow may be piped to the lower level within the shaft structure or may be allowed to drop freely 

within the shaft. Piping the flow allows for smooth directional transitions and minimizes turbulence, 

which can cause excessive hydrogen sulfide release and corrosion/erosion in sanitary systems. In some 

cases, spiral drop (vortex) structures are used to reduce velocities. 

Rehabilitation issues for drop shafts will need to be determined on a case-by-case basis depending on the 

depth of drop, the internal structures present, and the degree of deterioration. 

3.3.6 Manholes and Other Chambers. Manholes are an integral part of wastewater collection 

systems. Manholes are typically spaced approximately 300 feet apart, but can be less than 100 feet or as 

far as 500 feet apart. Using these values, the number of manhole structures in the U.S. can be roughly 

estimated at over 12 million. Older manholes are typically brick or concrete structures and may suffer 

from a variety of deterioration mechanisms. 

	 Hydrogen sulfide release may attack concrete manholes and the mortar in brick 

manholes. 

	 Manholes may leak allowing soil fines from the surrounding ground to enter the 

manholes, hence causing soil voids and surface settlement adjacent to the manholes. 

	 In cold climates, the upper portion of the manhole may be lifted by frost heave in the soil 

in the winter, thus fracturing the manhole and providing an infiltration path into the 

manhole. 

	 Newer plastic manhole materials avoid some of the corrosion issues, but some have been 

inadequately designed against excessive deflections due to ground loadings. 

	 Corrosion of ladder access or cast-in-place rungs can be an important safety issue in 

manholes. Some utilities remove such fixtures during the rehabilitation work. 

Rehabilitation approaches use techniques similar to those of piping systems but can take advantage of the 

person accessibility available. Specific techniques, listed in Appendix D, fall into the following 

categories: 

 Casting a new internal lining using permanent or removable forms 

 Sprayed or centrifugally cast concrete linings 

 Sprayed polymer linings (coatings or high-build structural linings) 

 Cured-in-place lining systems 

 Grouting and sealing approaches (including the flood grouting approach used for 

simultaneous manhole, mainline, and lateral sealing). 

Many agencies rehabilitate manholes as they rehabilitate the mainline sewers in an area (unless urgent 

action is needed on manholes located in other areas). As for mainline and lateral rehabilitation, effective 

techniques for such rehabilitation do exist and full manhole replacement is an option if the structure is too 

badly deteriorated for rehabilitation. Special considerations for manholes include: 

	 The structural thickness requirements of manhole linings vary with the depth below 

ground level and/or groundwater level. If the thickness of linings is set for the maximum 

load condition, then the manhole rehabilitation may be more costly than necessary. 

20
 
 Manhole diameters are much larger than most sewer pipes and hence the thicknesses of 

liners necessary to resist buckling against external groundwater pressures become 

significant for the more expensive polymer materials. 

 Most calculations for a structural lining do not take any account of bonding with the 

manhole structure although, for a sealant coating, the bond is critical in terms of the 

ability of the coating to resist seepage pressures. 

3.4 Other Wastewater Issues 

3.4.1 Inspection and Assessment. All rehabilitation and replacement works depend on some form 

of inspection and consequent assessment of the sewer line. A closed-circuit television (CCTV) survey is 

the predominant method in gravity sewers. However, there are many unmet needs of utilities in terms of 

equipment and data acquisition when carrying out an inspection. The main issues raised in extensive 

surveys are: 

For gravity pipe systems: 

 Improvements in current CCTV systems 

 Higher resolution and better lighting 

 Tractors better able to negotiate debris, grease, pipe separation, and corrosion 

 Improved cleaning procedures undertaken during CCTV work 

 Cameras for lateral inspections 

 A combination of CCTV and sonar to inspect partially full or surcharged sewers 

 A means to determine the remaining thickness of a corroded pipe, or determine the 

severity of a defect by measurement of the width and depth of a crack or hole in the pipe 

wall 

 The ability to measure the depth of crown corrosion in a concrete pipe 

 A method to measure sediment depth in large diameter pipes with heavy flow 

 A means to locate sewer laterals accurately 

 A means to quantify accurately deformations and out-of-roundness 

 A means to quantify joint anomalies – steps and openings 

 A means to map sewers that have deviations in line and level, and translate these directly 

to Geographic Information System (GIS) 

 A means to locate buried manholes 

 A means to locate voids on the exterior of a pipe. 

For pressure pipe systems: 

 A means to determine the remaining thickness of a corroded pipe, or to determine other 

defects such as cracks or pitting in the pipe wall 

 A means to determine the magnitude of internal corrosion in a metallic pipe 

 A means to locate leakage 

 A means to do all of this with the main in service. 

In many cases these capabilities already exist, whether within the sewer inspection industry or in others 

from which they may be adapted, but the awareness of these capabilities remains patchy. In the force 

main segment, it is seldom feasible to take a main out of service for inspection. No cost-effective 

technologies exist for inspecting while in service – so, as a result, there is almost no inspection of force 

mains undertaken. 

21
 
3.4.2 Inspection and Condition Assessment Standards. Standards for inspection, coding of 

defects, classification of condition, and rehabilitation itself have been slow to develop in North America. 

Existing standards are either industry-developed or adaptations of standards and codes developed 

overseas. 

The National Association of Sewer Service Companies (NASSCO) has adapted the UK’s WRc pipeline 

assessment standards to form a Pipeline Assessment and Certification Program (PACP) in an attempt to 

standardize the interpretation of CCTV inspection findings for sewer mains. They have also released a 

similar program for manholes, the Manhole Assessment and Certification Program (MACP). The 

development of standard defect codes, a standard data format, and condition ratings need more 

widespread implementation. Lack of such standardization causes subjective and inconsistent 

interpretation of data and precludes the ability to achieve any sort of benchmark of condition even within 

a single utility, let alone among several. However, the current penetration of PACP usage is still 

estimated to be low, and some cities complain that, given the high workforce turnover, it is difficult to 

keep staff sufficiently trained in the system for reliable coding. 

3.5 Summary of Wastewater System Issues 

Existing technologies for rehabilitation of all elements of the wastewater collection infrastructure (namely 

main sewers, force mains, laterals, and ancillary structures) are widely used and their performance so far 

has shown that they do provide extended service life to the infrastructure. The difficulty is knowing the 

full service life of the rehabilitation and hence its relative life cycle cost compared to full replacement. 

Here to date there has not been a well documented, unbiased retrospective program aimed at quantifying 

the condition of previously installed liners so factual evidence can be provided to aid in assessing future 

service lives. Plus, continuous improvements are being made to these technologies, especially in the less 

mature segment of laterals and the re-establishment of lateral connections after mainline rehabilitation, so 

the performance of older technologies may not be indicative of today’s products. New structural and 

semi-structural high-build polymer linings are also being developed and commercialized. 

The mature segment of main gravity sewer rehabilitation is dominated by CIPP methods. The use of ultra 

violet (UV) light curing was developed in Europe and is now entering the U.S. market. This innovation, 

which has changed the competitive dynamics of the major European markets, is likely to lead to greater 

cost-effectiveness and improved performance in the U.S. as well. UV-cured products have a long shelflife after impregnation if kept protected from light. This allows a break in the supply chain between 

impregnation and installation, which provides flexibility in separating the two activities and the 

organizations undertaking them, as well as a time separation. Construction footprints are also smaller as 

large hot water boilers and steam generators are not required to cure the CIPP resin. However, there is 

little parallel innovation in business models and this continues to be a brake on the market. New 

technologies, when introduced into the market, tend to use protective business models such as narrow 

licensing. Adoption of more open models would increase accessibility and the rate of penetration, albeit 

at potentially lower margins, leading to expansion of the market and greater competition. This 

phenomenon has already been seen in the trenchless arena when the business model underlying pipe 

bursting was changed and became more open. 

Nevertheless, there remains scope for innovative new technologies to penetrate the market as they are 

developed. Innovative new technologies need to respond to the need to improve cost-effectiveness so that 

significantly more sewerage infrastructure can be rehabilitated within available budgets. One technology 

that could drive such a step change in the market is spray-applied structural lining for gravity sewers. 

While previous efforts by several developers to commercialize such a technology have failed due to 

problems with the rapid curing of the resins, several companies across North America are striving to 

improve both the robotic spray-on technology and the formulation of the spray-on products. The benefit 

22
 
of structural spray-on lining is that it obviates the need for reopening lateral connections after lining and 

the speed of application of the lining and rapid cure can lead to higher installation productivity. 

Better inspection technologies, well-targeted inspection procedures and frequencies, accurate condition 

assessment, and improved deterioration models will continue to be very important in targeting scarce 

rehabilitation funding to its most effective use. Newly developed digital scanners and laser profilers are 

already providing many utilities with new tools to better quantify the condition of their buried wastewater 

assets and even quantify and track degradation rates over time. On a system-wide level, there is a 

continued need to understand how to deploy resources for capital investment, maintenance, and renewal 

among the interlinked processes of collection, storage of wet-weather flows, and wastewater treatment 

most effectively. 

23
 
 

4.0 WATER SYSTEM ISSUES 

4.1 Background 

4.1.1 Infrastructure Investment Needed. In the May 2001 publication “Dawn of the 

Replacement Era, Reinvesting in Drinking Water Infrastructures” (AWWA, 2001a), AWWA estimated 

that there were just over one million miles of water mains serving 273 million people in the U.S., and that 

a staggering $325 billion would have to be spent over a 20-year period to revitalize the aging 

underground infrastructure. The Government Accounting Office (GAO) in a 2002 report stated that 33 

percent of water utilities did not adequately 

maintain assets and a further 29 percent had 

insufficient revenues to even maintain 

current service levels. The EPA’s 2002 

report “The Clean Water and Drinking Water 

Infrastructure Gap Analysis” attempted to 

reach a common quantitative understanding 

of the potential magnitude of investment 

needed to address growing population and 

economic needs (EPA, 2002). Numerous 

other studies, including the annual ASCE 

Infrastructure Report Card (ASCE, 2007), 

clearly show the impact of lack of significant 

investment on the performance of our aging 

underground infrastructure. Unless 

significant action is quickly taken, the problem will only worsen as the average pipe age continues to 

increase without significant replacement or renewal. As shown in Figure 3, the average pipe age in 2008 

is about 38 years old, but by the year 2050 the average pipe age will be 50 years old. This is because of 

the boom in water pipeline installations that took place after WWII. From 1870 to 1945 less than 20,000 

miles of pipe were installed each decade. However, after 1945 this rate increased to over 80,000 miles of 

pipe. The commonly accepted design life for a water distribution or transmission main was 

approximately 50 years. Many pipes, especially older cast iron water mains, which had very thick pipe 

walls compared to today’s AWWA standards requirements, have had useful service lives in excess of 100 

years. However, minimum wall thickness requirements for ductile iron pipes have dropped over the years 

due to competitive pressure from thermoplastic materials, resulting in an increased frequency of failures 

in ferrous pipes. The design basis for thermoplastic and glass-reinforced thermoset pipes is predicated 

upon applying a suitable factor of safety to the pipe material’s predicted tensile strength under a constant 

load in 11.4 or 50 years, respectively. Many of the ferrous and polymer-based water pipes will provide 

adequate service for at least 50 years, especially at reduced service pressures, but the frequency of failures 

will start to increase. For corrosion related failures, the rate of increase can be exponential. Depending on 

the service conditions, some pipes can be considered “middle-aged” at 50 years, while others must be 

considered “old” or near the end of their life cycle. 

4.1.2 Pipe Material Usage. Water mains can be categorized as either distribution piping (2-inch to 

10-inch diameter) or transmission mains (12-inch diameter and greater). Approximately 73 percent of all 

water mains, by length, are distribution pipes. Typically pipe diameters less than 30 inches are 

considered non man-entry size, so any inspection or trenchless rehabilitation needs to be done remotely. 

This covers 93 percent of the entire population of water mains. Tables 4, 5, and 6 provide some statistics 

on the distribution of pipe materials, pipe diameter, and age in the U.S. water distribution network. 

Figure 3. Historical and Projected Average Age of 

U.S. Water System (EPA, 2002) 

24
 
 

Diameter Range, % of 

inches Miles Installed Total 

<6 107 200 12.4 

6 to 10 523 200 60.6 

12 to 16 138 600 16.1 

18 to 24 29 700 3.4 

30 to 48 57 700 6.7 

> 48 6 600 0.8 

Total 863 000 100 

Age, 

years 

Miles 

installed 

% of 

Total 

0 to 10 245 000 28.4 

10 to 25 325 500 37.6 

25 to 50 156 500 18.1 

>50 137 000 15.9 

Total 863 000 100 

Table 4. Water Distribution Systems by Material (AWWA, 2004) 

Material Miles Installed 

% of 

Total 

Asbestos Cement 136 196 15.8 

Cast Iron unlined 153 415 17.8 

Cast Iron cement mortar lined 159 824 18.5 

Cast Iron 28 476 3.3 

Concrete Prestressed 23 584 2.7 

Ductile Iron unlined 35 916 4.2 

Ductile Iron cement mortar lined 150 705 17.5 

Ductile Iron other lining/lining not known 2 494 0.3 

GRP 665 0.08 

PE 3 349 0.4 

PVC 114 152 13.2 

Steel 34 047 3.9 

Other/Not known 20 169 2.3 

Total 863 000 100 

Table 5. Water Distribution Systems by 

Diameter (AWWA, 2004)
 

Table 6. Water Distribution Systems by Age 

(AWWA, 2004) 

Up to the 1940s, water mains were chiefly unlined cast iron and steel. Cast iron (CI) pipe eventually gave 

way to ductile iron (DI) pipe and ceased being used altogether in the mid 1980s. Today, 56 percent of all 

underground water mains are CI pipe. The primary problem with unlined CI pipe is both internal and 

25 
 

external corrosion. Internal corrosion causes tuberculation, which can lead to water quality issues and 

reduced flow and pressure. Internal corrosion can also result in wall thinning that weakens the pipe and 

holes to cause leakage or eventually rupture. CI pipe is also susceptible to external corrosion if not 

protected. Graphitization of CI pipe is a type of corrosion that weakens the pipe wall by the removal of 

iron, leaving graphite behind. Graphitization is not easily detected, because the appearance of the pipe 

remains unchanged. Weakened pipes can fail under much smaller fluctuations in pressure (i.e., surge), 

frost heave, ground movement or thermal stress (due to rapid changes in water temperature). Also, the 

relative thickness of CI pipe was gradually reduced over the years as production and material technology 

improved. For unprotected ferrous pipes, the National Standards Bureau found the rate of corrosion to be 

similar for all ferrous pipe types. Consequently, younger unprotected CI pipe with thinner walls can 

actually pose a greater failure threat as less time is needed to penetrate the reduced wall thickness. CI 

pipe is also susceptible to failure at corporation stops due to galvanic action between the two dissimilar 

materials, which leads to leakage. If the leakage continues over time, the underlying bedding may be 

compromised and bending loads induced by loss of beam support (e.g., as a result of loss of bedding), 

which result in circumferential cracks. 

Asbestos cement (AC) was initially developed in Italy and introduced to the U.S. market in the late 

1940s. Being non-metallic, AC pipe was not subject to galvanic corrosion. However, soft water will 

remove calcium hydroxide (free lime) from the cement and eventually lead to deterioration of the pipe 

interior (softening accompanied by release of asbestos fibers). External exposure to acidic groundwater 

(e.g., mine waste) or sulfates in the soil can also lead to deterioration of the cement matrix. Type II 

Portland cement, which reduces the negative impact of sulfate, was not always used. The production of 

AC pipe ceased in the U.S. in 1983. However, despite the cessation of production, approximately 15 

percent of all water mains today are asbestos-cement. This percentage is much higher on the West coast 

(closer to 20 percent) where AC pipe was more widely used. 

Approximately 22 percent of the existing underground water main infrastructure is DI pipe. DI pipe was 

introduced to the utility market in 1955 and eventually displaced CI pipe completely. Initially, DI pipe 

was unlined, but by 1975 most DI pipe marketed for water service was lined with cement mortar. Also, 

as external corrosion issues were observed, unbonded loose polyethylene (PE) sleeves were later made 

available for field application to electrically isolate the pipe from the soil; and these sleeves have 

performed with varying degrees of effectiveness (Szeliga, 2007). The U.S. DI pipe industry currently 

does not offer DI pipe with bonded coatings, as done by the steel pipe industry. The industry, as 

represented by the Ductile Iron Pipe Research Association (DIPRA), contends that external corrosion 

protection is not normally required for DI pipe, and when corrosive soil conditions exist, the PE sleeves 

are totally adequate and cathodic protection unnecessary. A bonded coating to the exterior surface, in 

conjunction with cathodic protection to handle any inadvertent holidays (e.g., pinholes or voids) in the 

coating, is generally considered to offer the highest level of corrosion protection (National Association of 

Corrosion Engineers [NACE], 1984; Sloan, 2001). 

Thermoplastic pipes, initially in the form of PVC and more recently PE, have also found use as 

underground water mains. In the U.S., PVC represents 10 percent of the underground water main 

infrastructure and is definitely the thermoplastic leader in this market. Acceptance for PE pipe, which is 

actually higher in Europe than that for PVC pipe, is growing slowly as utilities gain more experience with 

the material. Thermoplastic pipes are not subject to electrochemical or galvanic corrosion. PVC pipes 

have experienced premature fatigue-related failures when used in cyclic pressure applications (e.g., 

irrigation systems and force mains). A Water Research Foundation (formerly American Water Works 

Association Research Foundation [AwwaRF]) study titled “Long-Term Performance Prediction of PVC 

Pipes” provides evidence that the longevity of a PVC pipe is directly related to its resistance to slow crack 

growth (SCG), which is dependent on the pipe’s fracture toughness and distribution and size of defects in 

26
 
 

 

the extruded pipe wall (Burn, 2006). Most PVC pipe failures tend to be brittle, not ductile, which tends to 

support the conclusions of the AwwaRF study. 

The performance of PVC pipe produced in the U.S. has been shown to be superior to that initially used in 

Australia and the U.K., where problems have been experienced. AwwaRF also completed a similar study 

on PE pipe, titled “Long-Term Performance Predictions of PE Pipes”, where the pipe’s longevity was also 

found to be dependent on the rate of crack growth, which is functionally tied to the fracture toughness of 

the material (Davis et al., 2008). 

Thermoplastic pipes, as well as AC and concrete pipes, have been shown in studies carried out in the 

Netherlands to allow low molecular weight hydrocarbon molecules to migrate through the pipe wall. The 

rate of migration is dependent on the molecular structure of the pipe material. The AWWA standards for 

PVC (AWWA C900 and C905) and PE (AWWA C901 and C906) contain warnings on the use of these 

materials in drinking water supply systems if the pipes pass through contaminated soils. Rubber ring 

gaskets are also susceptible to the migration of low molecular weight hydrocarbons, so caution needs to 

be taken with the use of other pipe products that use rubber gasket joints in contaminated soils. Exposed 

surface areas are generally much smaller for a rubber gasket joint mitigating the severity of the problem. 

Thus, the million miles of aging water mains are made of a vast array of different types of pipes, with and 

without corrosion protection systems. The failure mechanism of each type of pipe is different meaning 

that rehabilitation solutions must be tailored to match the problems experienced by a specific type of pipe 

material, or be flexible enough to cover a multitude of performance problems. The latter is not as likely. 

4.1.3 Drivers for Water System Rehabilitation. The U.S. water industry has an environment 

different from the wastewater industry when it comes to the amount of rehabilitation undertaken or even 

contemplated. Formal enforcement action by EPA on communities with excessive CSOs and SSOs 

during wet weather has definitely been a spur to action. For example, the threats of hefty fines for 

overflows or spills is driving many communities to undertake I&I reduction programs that often involve 

some form of sewer main rehabilitation. Without the threat of such external and costly enforcement 

actions, the political environment in many communities would make it difficult to raise the necessary 

funds to improve the condition of its wastewater system to an acceptable level. Water systems also are 

harder to inspect as ordinary visual inspections will reveal little about the structural condition of the 

mains, and require expensive and/or time consuming temporary services and disinfection in conjunction 

with rehabilitation. With well-developed emergency repair strategies, many water utilities currently find 

the repair option cheaper than establishing a systematic rehabilitation program. 

In the U.S., approximately 160,000 public water systems are subject to the Safe Drinking Water Act 

(SDWA). The SDWA requires EPA to establish National Primary Drinking Water Regulations 

(NPDWR) for contaminants. Mandatory maximum contaminant levels (MCLs) and non-enforceable 

maximum contaminant level goals (MCLGs) are established by EPA. The 1996 Amendment to the 

SDWA established the Drinking Water SRFs. States can use the funds to help water systems make 

infrastructure improvements or assess and protect source water. Unfortunately, the amount of money 

allocated to the revolving funds has decreased over the years. The amount of money available in the 

SRFs is miniscule compared to the amount needed to rebuild the infrastructure. 

Primacy states have administrative penalty authority, and many types of formal enforcement actions are 

possible. However, fines are small in comparison to those for wastewater overflows, so utility efforts 

tend to focus more on source water and treatment issues rather than distribution and transmission 

improvements. For example, service interruptions as a result of a failure, inadequate flow, or low 

pressure, all of which can be very upsetting to the utility customers, but do not warrant enforcement 

action under the SDWA. 

27
 
The main driver pushing utilities to undertake any rehabilitation work on their underground infrastructure 

is the direct and indirect costs associated with cumulative failures in a water main. As an example, the 

City of Cleveland, Ohio has experienced two breaks in a 36-inch CI water main located in the center of 

the business district. The Cleveland press reported that the cost to repair the first break, and restore 

damage done from flooding, combined with the business losses associated with a complete shutdown for 

two days, was about $1.5 million. After the second failure, the City decided to aggressively take action to 

upgrade this line because the estimated cost to rehabilitate was less than the costs associated with these 

failures. More common types of failure involve the repeated failure of a pipe, aggravating customers and 

causing repeated repair to become economically unfavorable in comparison to renewal. 

4.1.4 Funding for Rehabilitation. As stated earlier, SRFs are insufficient to cover the costs for 

rehabilitating an aging water system. Rate structures for pubic water utilities typically are not designed to 

provide the level of funds needed either. Water rates are politically sensitive and, without significant 

increases over the years, often do not even cover the cost of providing clean water to stakeholders. One 

of the paradoxes of the water industry is that life is impossible without water, yet we are only willing to 

pay a fraction of the cost of what it takes to deliver safe, clean water to our homes and offices. Public 

utilities will need to find a way to raise rates to match the value of water to society so that money 

becomes available for renewing the aging infrastructure. In recent years, the federal government has been 

unwilling to step in and provide those funds. In the coming years, a renewed interest in infrastructure 

provision and the need for an economic stimulus may change the funding outlook. 

Regrettably, it may take a significant disaster, as occurred in Walkerton, Ontario, to force politicians to 

take action on rate increases. An outbreak of E. coli due to operator error in Walkerton, Ontario, in May 

2000 resulted in the death of seven people from drinking contaminated water. Two thousand people 

suffered from the symptoms of the disease. The disaster prompted a surge of regulations and other 

enforcement measures, resulting in water rates tripling in many Canadian municipalities (Holme, 2003). 

Utility operators have commented, however, that there were actually few documented water quality 

events related to pipe failure (with new regulations in place concerning “boil water” orders). 

4.1.5 Potable Water – NSF International (NSF)/American National Standards Institute 

(ANSI) Standard 61. Federal and State governments encouraged the development of a consensus 

standard that could filter out products not suitable for use in the conveyance of potable water. The NSF 

International in Ann Arbor, Michigan spearheaded the development of NSF/ANSI Standard 61, which 

covers products in direct contact with potable water. Pipe and joining materials must undergo a searching 

evaluation of formulation, toxicology, and product use and a rigorous testing program that includes water 

immersion under controlled conditions and testing for migration of contaminants, odor, and taste. The 

testing protocol can take up to six months and the cost to the supplier interested in getting an NSF listing 

against Standard 61 may reach many thousands of dollars. In the U.S., it is virtually impossible to supply 

a pipe, liner, or sealing mechanism (i.e., gasket) for a potable water application that is not NSF/ANSI 

Standard 61 listed. The exception is products that have been grandfathered due to extensive past usage, 

such as cement mortar linings. Products that are made from organic compounds, such as polyester resins 

and their catalyst systems, especially if they incorporate styrene, have particular difficulties in this regard. 

When the chemistry is brought to the field and curing is done under non-laboratory or less controllable 

conditions, it becomes even more difficult to get an NSF/ANSI Standard 61 listing. Only a few CIPP 

suppliers have NSF 61 listings. They have usually achieved acceptance by using epoxy resins, which are 

more costly than polyester resins, or by incorporating a polyethylene or polyurethane coating that 

separates the resin body from the potable water stream. Initially there was only one spray epoxy resin 

system that had an NSF 61 listing, now there are a dozen approved systems, but it has taken 15 years to 

achieve that level of acceptance. Some spray polyurethane resin systems, which use the same application 

process as epoxy, have also gained NSF 61 listings. A more streamlined testing program, and at lower 

28
 
 

cost, would allow other concepts to be tested easily and quickly – broadening the number of rehabilitation 

options available and eventually at lower cost. 

4.1.6 Service Connections. Water mains, especially distribution pipes and service lines, may be 

buried with as little as 30 to 36 inches of soil cover in non-frost areas. In some northern areas, where 

frost penetration dictates deeper burials, up to 8 feet depths may be required. With water service 

connections every 25 to 50 feet, many water utilities feel that it is just as cost-effective to dig up and 

replace the entire main as to rehabilitate the main using trenchless methods if every service connection 

has to be excavated to be reinstated. In-line fittings almost always have to be replaced, which requires 

open-cut excavation, again minimizing the value of using trenchless techniques. 

Several vendors have introduced products and procedures for remotely reinstating service connections 

from inside a lined main. Insituform’s iTap mechanically locks the new liner to the existing corporation 

stop from inside the main without excavation. Sanexen has also developed a procedure for remotely 

sealing the area between the new liner and the service connection. Both of these are promising and may 

encourage more utilities to attempt trenchless rehabilitation over outright replacement. Another area of 

recent development has been in the application of keyhole “soft” excavation techniques to core through 

the road pavement and dig small diameter holes down to the service connection. Repairs to the line or 

new service connections are then made using special long handled tools within the keyhole excavation. 

These techniques have been pioneered mostly within the gas industry, but they also can be used in the 

water and wastewater sectors. 

4.1.7 Experienced Contractors. The U.K. and Australia are often considered to be about 10 years 

ahead of the U.S. when it comes to asset management and water main rehabilitation. The majority of 

water main rehabilitation in the U.S. has consisted of cleaning and lining (cement mortar lining) of mains 

or replacement. Most lining used to date is a nonstructural rehabilitation method (thin internal coating) 

suitable only for pipes that have internal corrosion issues contributing to water quality or flow problems. 

Many contractors are experienced with CIPP lining gravity sewer mains, but only a handful have pressure 

pipe experience. Likewise, the use of close-fit PE and PVC liners, and other new rehabilitation 

technologies, has been very limited to date in the water industry, so finding experienced contractors can 

be difficult. Experienced contractors must also be familiar with installing temporary bypass systems and 

protecting water quality integrity. Many utilities incorporate experience requirements in tendering 

documents, which makes it very difficult to find a local contractor that meets those requirements. 

It is very difficult to introduce a new rehabilitation technology into the U.S. water market. There is 

tremendous inertia to follow past practices and not consider new technologies or methods that might draw 

criticism if unsuccessful. Well documented and publicized demonstration projects by credible 

organizations can be important in overcoming this conservatism in addition to making available suitable 

standards and specifications for the new techniques. 

4.1.8 Standards. As mentioned above, one way to overcome the reluctance of U.S. municipal 

engineers to try new rehabilitation technologies is through well developed consensus specifications that 

cover all of the necessary short-term and long-term performance requirements, along with the tests that 

demonstrate conformance to these requirements. Currently, these are significantly lacking for water 

rehabilitation technologies. At present, there are no AWWA specifications for rehabilitation of water 

mains, with the exception of cement mortar lining. For any national or consensus rehabilitation 

specifications or standards, one has to turn to NASSCO or use the available ASTM standards. NASSCO 

only has sewer specifications and derives most of its specifications from vendors or groups of vendors. 

ASTM has several specifications for the lining of pipes with cured-in-place liners (F-1216, D-5813, F1743, F-2019, and F-2207). AWWA has just released C620-07, Spray Applied Epoxy Liners (AWWA, 

2008). It has also been reported that the AWWA Rehabilitation Standards Committee is working on 

29
 
 

standards for pipe bursting and interior joint seals, which are nearing completion. However, many other 

types of pipe liners such as close-fit PE and PVC, spray epoxy or polyurethane, etc., are not adequately 

addressed by any national standard. Even more to the point, there are no national standards covering the 

full range of structural design issues for liners in deteriorated pipes. The design of the liner is dependent 

on the condition of the host pipe. The norm is to refer to the condition of the host pipe as either partially 

deteriorated or fully deteriorated, but the determination of these conditions is largely subjective. Either 

the liners are semi-structural, designed to bridge or span holes of a given dimension, or they are fully 

structural and capable of carrying the full internal design pressure should the host pipe fail completely. 

Once again, the guidelines for determining what type of rehabilitation liner is needed are vague. The 

ASCE Pipeline Infrastructure (PINS) committee was attempting to establish better guidelines for the 

design of pressure and non-pressure liners, but the committee’s report lacked sufficient detailed guidance 

and consequently has not been found very useful by the engineering community. 

4.1.9 Maintenance Concerns. The operations and maintenance (O&M) staff of a utility are given 

the task of repairing failures that occur in a water main. They also have to operate the system, which 

often means cutting in new valves or taps for new services. Field crews are trained to work with the type 

of pipe materials that the utility has in its system. Repair clamps, mechanical couplings, and spare pipe 

sections are usually kept in inventory to handle emergency repairs. Instructions for repairing a pipe that 

has been lined with a close fit PE liner or CIPP are not widely publicized or known. As a consequence, 

O&M staff will tend to favor replacement of a deteriorated main with a pipe with which they are familiar, 

even if at a significant cost premium over a renovation lining technology. Until vendors can demonstrate 

practical methods for repairing damaged or failed mains that incorporate these new innovative liners, 

there is going to be continued reluctance on the part of O&M personnel to accept them as viable options 

to outright replacement. 

4.2 Summary of Water System Issues 

The water infrastructure in North America is older than the wastewater infrastructure. At the current pace 

of replacement (less than 1 percent per year) and installation of new pipes, the average age of the 

underground pipe infrastructure will gradually approach the commonly accepted design life of 50 years in 

2050. Many pipes have been known to operate longer than their design life, but the frequency of failures 

increases with the age of the infrastructure. This means that unless a more aggressive rehabilitation 

program is adopted now, communities are going to be hit with significantly increasing repair costs in the 

not too distant future. The current drivers that exist in the wastewater side of the industry, including 

punitive actions for CSOs and SSOs, do not exist in the water industry. Water rates have historically 

been set at levels that do not truly reflect the value of this precious commodity, and politicians have been 

reluctant to adopt rate structures that would provide the necessary funding to make water utilities self 

supporting and sustainable. 

Leadership in the area of design standards development for renewal and trenchless replacement 

technologies has been slow to evolve in North America. The design of a liner can be non-structural, 

semi-structural, or fully structural dependent on the level and type of deterioration in the host pipe. This 

determination is entirely subjective with little guidance provided by the expert community. 

Techniques for the repair of pipes with liners are not well understood by those in charge of maintenance 

and operations in a water utility, and adding new materials and/or technologies is not readily welcomed 

by those who receive failure calls at 3 a.m. It will be many more years before a large body of contractors 

with significant water main rehabilitation experience exists – similar to what exists today in the 

wastewater side. Communities are reluctant to try new technologies especially with inexperienced 

installers who are also in the process of learning. 

30
 
Streamlining the NSF Standard 61 approval process such that vendors can get more products screened 

quicker, and for less money, might open the door to more innovation in the industry. 

Effective inspection and condition assessment of water pipe is generally difficult or extremely costly to 

carry out. Targeting mains for rehabilitation and replacement is largely centered on performance 

assessment: main break frequency or severity, water quality problems or poor hydraulic characteristics. 

Recently, emphasis on structural defects has shifted to improved leak-detection technologies that seek to 

reduce the loss of water and quickly identify faulty pipe to reduce the cost of repair and consequence of 

failure. Predictive models for deterioration based on pipe materials, ground conditions and failure history 

are considered useful in identifying the extent of the present and near future needs for rehabilitation. 

31
 
 

5.0 CURRENT TECHNOLOGIES AND POTENTIAL FOR IMPROVEMENT 

A wide variety of techniques exist to prolong the performance life of water and wastewater system assets 

or effectively replace the assets in situ. In practice, the applicability of each technique is evaluated based 

on the condition of the existing asset, site circumstances, cost, track record and local availability of the 

technique, and its expected ability to meet new performance requirements over an extended life cycle. 

Each technique has found its market niche and some technologies compete with others over a wide range 

of applications. In trying to improve the performance and cost-effectiveness of rehabilitation 

technologies, current methods represent the standards against which new technologies or the evolution of 

current technologies must be measured. 

Descriptions of the wide range of commercially available methods for rehabilitation of wastewater 

collection and water distribution systems are provided in Appendices B and C, respectively. The 

emphasis is on methods that are in use or being introduced within the U.S. For each method, a very brief 

description of the method is given together with examples of the commercial providers of this method. 

Rehabilitation includes both replacement and renovation or renewal of an existing pipe. Emphasis will be 

placed primarily on the renovation/renewal side of rehabilitation (including trenchless replacement via 

pipe bursting) although replacement by open cut, microtunneling and horizontal directional drilling 

(HDD) methods must also be considered. For water systems, the need for installation of temporary 

services lines is a major cost issue. 

The range of technologies and their potential applications is summarized in Tables 7, 8 and 9. The 

application conditions are not intended to be absolute indicators but rather to represent the common range 

of practice. Taken together, these methods vide the state-of-the-practice for rehabilitation in the water and 

wastewater sectors and the opportunities to provide substantially increased value to utilities. They 

provide a wide range of innovative and cost-effective solutions, but there is still plenty of room for 

extension and refinements of existing methods and the addition of new approaches. Each of the 

categories of rehabilitation technologies is evaluated below in terms of the potential for additional 

advances or refinement in the near- to mid-term (i.e., less than 5 years or 5-10 years). 

5.1 Sliplining 

This is a mature technology with a number of pipe products available for use in sliplining. Changes in 

technology that would allow more cost-effective installations could include the ability to negotiate 

moderate bends within the length of a sliplined section, improved sliplining pipe materials and/or 

improved grouting materials. One innovation is sliplining a prefilled, pre-disinfected pipe in drinking 

water applications which can greatly speed the return to service of the water line. The use of ductile iron 

pipe for sliplining and fusible PVC are relatively new alternatives to HDPE pipe. Remote reinstatement 

of service connections would also be a major benefit. 

5.2 Spiral-Wound Liners 

This technology spans the range between ungrouted circular liner systems for small, circular pipes to noncircular, custom-profiled liners for large pipes and tunnels. Most of the experience with the systems has 

been overseas, but the technologies have been used in the U.S. over a full range of pipe sizes and for both 

circular and non-circular profiles. Since the profiles, their locking mechanisms, steel reinforcing strips, 

etc., vary from system to system, there is still a need to provide a performance history tied to the specific 

attributes of each lining configuration. 

32
 
 

 

 

 

5.3 Cured In Place Pipe Liners 

This is a mature technology in one sense, since CIPP liners have been installed since 1971. However, 

changes in the technical and operational aspects of CIPP lining continue to evolve. These are driven 

partly by technical innovations and partly by the need to stay competitive both within the CIPP market 

and in terms of competition with other liner systems. Recent innovations applicable to the U.S. market 

are in the introduction of UV-cure liner systems, the increased use of steam cure in place of water cure, 

the refinement of site operations to recycle hot water used for curing, the introduction of composite liner 

technologies and the expansion of the number of industry providers of CIPP installations. The challenges 

are the increasingly stringent controls on chemicals that may enter the aqueous or air environment and to 

maintain high levels of QC in a more commodity-driven business environment. 

5.4 Close-Fit Liners 

Close-fit liners involving the fold-and-form or symmetrical reduction system have a long track record of 

use in wastewater and water systems in the U.S. Swagelining and Rolldown systems have mainly been 

applied in water pipe rehabilitation. A factory-manufactured pipe is installed, but careful QC is still 

needed in the field during pull-in and expansion to fit the host pipe. Protruding service connections may 

also be a concern. Insituform Blue has recently introduced its PolyFlex and PolyFold products for the 

water industry which are HDPE close fit liners. The Insituform Blue products use 4710 (PE100) grade 

polyethylene, which has a 25 percent higher hydrostatic design basis (HDB). The newest entry to this 

sector is the Tight-in-Pipe (TIP) system which is more-or-less a hybrid of sliplining in conjunction with a 

minimal pipe bursting operation. 

5.5 Grout-In-Place (GIP) Liners 

The Trolining system remains relatively novel in the U.S. despite a number of years experience in use in 

Europe – especially in industrial applications. The system has significant flexibility in terms of total liner 

thickness, structural capacity, and leak containment and detection capabilities. An emerging technology 

in this category is the Mainsaver system which uses a thin studded polyethylene sheet that is anchored 

into a grout layer. The grout is distributed along the liner at the same time that the liner is inflated to fit 

tightly against the host pipe. 

The liner offers relatively low cost installation with some level of structural bridging capability (Type II1 

liner as defined in AWWA M28 Rehabilitation of Water Mains (AWWA, 2001b). 

5.6 Panel Liner Systems 

Several structural panel lining systems are available in the U.S. market. These are essentially site 

fabricated, modular structures. There is still scope for innovation in terms of specific materials and 

installation procedures. An important issue is loading characteristics that should be considered for the 

liner design for deteriorated but still structurally adequate host pipe or tunnel systems. This issue also 

applies to most large-diameter liner systems. 

5.7 Sprayed Coating and Liner Systems 

The difficulty of providing a clean, sound surface for bonding of sprayed linings is a major impediment to 

the use of thin sprayed linings for corrosion control. Clean surfaces are particularly of concern in the 

1

 Type II liners are semi-structural, not capable of independently sustaining the full operating pressure on a long 

term basis but able to span holes and joint gaps, resistance to external loads depends on adhesion to the host pipe. 

33
 
5.8

wastewater sector. High-build linings can develop sufficient ring strength and stiffness and can function 

even with a poor bond. This is probably the growth area for sprayed linings in the wastewater sector – 

both using traditional materials such as shotcrete in culvert rehabilitation and using high-build polyureas 

and polyurethanes in pipe rehabilitation. In the water industry, sprayed polymeric compounds are having 

increasing success and achieving rapid cure times. In the water sector, the emphasis is shifting towards 

use of sprayed coatings as semi-structural and structural spray linings. Also available are carbon fiber 

reinforced pipe liners (CFRP) that can be used for local reinforcement of person-entry pipelines or a 

seismic upgrade of sections of pipelines. 

 Flood Grouting 

Flood grouting is another wastewater rehabilitation system that has been used far more extensively in 

Europe than in the U.S. Three systems are potentially available for use, but more, well-documented field 

experience will help to increase confidence in the use of the technique and will provide comparative 

performance with separate mainline, lateral and manhole sealing systems. 

34
 
35
 

Table 7a. Overview of Sewer Pipe Rehabilitation Methods—Mature Technologies 

Method 

Pipe Parameters 

ID 

Diameter 

Range** 

Repair 

Length Plugging 

Work Requirements 

Pit 

Excavation 

Resin/ 

Coating** 

* Cure 

Time 

Annular 

Space 

Grouting 

Structural 

Repair 

Excavation 

for Laterals 

Reopening 

Cr

Sec

Cha

1. Level of Cleaning required: Good / Very Good 

CIP, standard 8-96” <2500’ Yes No Yes No Yes No Decr

CIP, Top Hat 4-20” M 

4-8” L 

1’ Yes No Yes No No No Decr

Reinforced gunite 35” <500’ Yes No Yes No Yes No Decr

Spraying, epoxy 3-36” <400’ typ. Yes No Yes No No Varies Decr

Robotic repairs 8-30” 24” No No Yes No Local No Sa

2. Level of Cleaning required: General 

Sliplining 4-150” <5,000’ No Yes No Yes Yes Yes Decr

Fold and form 3-30” <1500’ Yes No No No Yes No DecrDeform-reform 3-59” <1,000’ Yes No No No Yes No Decr

Compression-based SR* 

4-20” <3,000’ Yes No No No Yes Yes Decr

Tension-based SR* 3-36” <3,000’ Yes No No No Yes Yes Decr

Chemical grouting 6-144” Varies with 

diameter 

Yes No Yes No No No Sa

Spot repair sleeves 36-108" 18-36" Yes No No Varies Local Yes Decr

GRP panels Man entry No Limit Varies Yes No Yes Yes No Decr

2. Level of Cleaning required: None / Not Applicable 

Pipe bursting, static 2-54” <750’ Yes Yes No No Yes Yes Sam

incr

Pipe bursting, pneumatic 

2-54” <750’ Yes Yes No No Yes Yes Sam

incr

Pipe bursting, hydraulic 

2-20” <750’ Yes Yes No No Yes Yes Sam

incr

Pipe extraction 1-60” <200’ Yes Yes No No Yes Yes Sam

incr

Pipe reaming 4-24” <600’ Yes Yes No No Yes Yes Sam

incr

* SR = Symmetrical Reduction; ** M = Mainline; L = Lateral; *** Not grouting. Table entries should be considered indicative of applications but n
-

36
 

Table 7b. Overview of Sewer Pipe Rehabilitation Methods—Emerging Technologies 

Method 

Pipe Parameters 

ID 

Diameter 

Range* 

Repair 

Length Plugging 

Work Requirements 

Pit 

Excavation 

Resin/ 

Coating 

Cure Time 

Annular 

Space 

Grouting 

Structural 

Repair 

Excavation 

for Laterals 

Reopening 

Cross 

Section 

Change 

1. Level of Cleaning required: Good / Very Good 

CIP, T-liners 6-24” M 

3-6” L 

<160’ Yes No Yes No Yes No Decrease 

Spraying, polyurethane 

Varies Varies Yes No Minimal No Varies Varies Decrease 

Spraying, polyurea Varies Varies Yes No Minimal No Varies Varies Decrease 

2. Level of Cleaning required: General 

Spiral winding 6-180”, 

12’×15’ 

<650’ No Varies Varies Yes Yes Yes Decrease 

Grout-in-place (GIP) 

6-80”, >80” 

(panels) 

<525’ Yes No Grout only Yes Yes No Decrease 

Internal joint sealing 

14-216” 7-10” Yes No Varies No No No Same 

* M = Mainline; L = Lateral. Table entries should be considered indicative of applications but not definitive for all products.
 

Emerging technologies are defined here as those that have been used commercially in a substantial number of applications in the U.S., but not yet recotechnology. 

Table 7c. Overview of Sewer Pipe Rehabilitation Methods—Novel Technologies 

Pipe Parameters 

Method 

ID Diameter 

Range* 

Repair 

Length 

Plug 

ging 

Pit 

Excavation 

Work Requirements 

Resin/ 

Coating** 

Cure Time 

Annular 

Space 

Grouting 

Structural 

Repair 

Excavation 

for Laterals 

Reopening 

Cros

Secti

Chan

1. Level of Cleaning: Good / Very Good CIP, composite 24-96” <700’ Yes No Yes No Yes No Decre

2. Level of Cleaning: General Flood grouting Not specific Not specific Yes No Yes No No No Sam

3. Level of Cleaning: Minimal Tight in place (TIP) 8-15” 500’ Yes No No No Yes Yes Decre

* M = Mainline; L = Lateral; ** Not grouting. Table entries should be considered indicative of applications but not definitive for all products. Novel technologies are defined here as those that have only been used at the pilot-scale, in a few commercial applications, or are new to the U.S. mark
Pipe Parameters Work Requirements F

Method 

Working 

ID Dia. Repair Pressure 

Range* Length psi 

Pit 

Excavation 

Resin/ Annular 

Coating** Space 

Cure Time Grouting 

Excavation 

for Service 

Reopening 

AWWA 

Classification 

C

S

C

Level of Cleaning Needed: Very Good 

Woven PE/epoxy lining 3-24” Varies 150 S/N Yes Adhered No II M

Level of Cleaning Needed: Good 

CIP 8-96” <2,500’ 200 S/N Yes No No III M

Deform-reform, PRP 3-12” <1,000’ 230 S/N No No No III M

Deform-reform, PE 3-48” <1,000’ 150 S/N No No No III M

Spraying, cement mortar 3-24” and up <1,000’ NK S/N Minimal No No I M

Spraying, epoxy 3-36” <1,000’ NK S/N Yes No No I M

Spraying, polyurethane 3-48” <1,000’ NK S/N Yes No NK II M

Spraying, polyurea 3-36” <1,000’ NK S/N Minimal No NK IV De

Level of Cleaning Needed: General 

Sliplining >4” <5,000’ 360 L No Varies Yes III De

Compression-based SR* 4-20” <1,000’ New pipe M/L No No Yes IV M

Tension-based SR* 3-36” <1,000’ New pipe M/L No No Yes IV M

Grout-in-place (GIP) 4-12” <600’ NK L Yes Integral No III De

Level of Cleaning Needed: None or Not Applicable 

Pipe bursting, static 2-36” 300­ 400’ New pipe L No No Yes IV S

in

Pipe bursting, pneumatic 2-36” 20-500’ New pipe M No No Yes IV S

in

Pipe bursting, hydraulic 2-36” NK New pipe M No No Yes IV S

in

Pipe extraction 1-60” NK New pipe M No No Yes IV S

in

Pipe reaming 4-24” 1,600’ New pipe M No No Yes IV S

in

Carbon fiber reinforced pipe (CFRP) 

Man 

entry NA High pressure M Yes No Yes IV M

Spot repair / joint repair 4-54” 12-36” Varies S/N Minimal Adhered or none N/A IV S

de

37
 

Table 8. Overview of Water Pipe Rehabilitation Methods 

* SR = Symmetrical Reduction; NK = Not known; S/N = Small or none; M/L = Medium or large; L = Large; AWWA classification of potable water rehabilitation systems I = Nonstructural; II = Semi-structural without inherent ring stiffness (depends on astructural with inherent ring stiffness (self supports); IV = Structural. 
38
 

Table 9. Overview of Manhole Rehabilitation Methods 

Method 

Manhole 

Parameters 

ID 

Diameter 

Range 

Height 

Range, ft 

Annular 

Space 

Requirements and 

Features of Rehabilitation Method 

Duration 

Invert 

Repair 

Bench 

Repair 

Removes 

Infiltration/ 

Inflow 

Structura

Repair 

Preformed manhole units 3.5–6 ft 3–25 ft Yes 6-8 hrs Yes Yes Yes Yes Poured-in-place concrete Any Any No 8 hrs Yes Yes Yes Yes 

Cured-in-place manhole (CIPM) 2.0–19 ft Any Yes 4-8 hrs Yes Yes Yes Yes 

Grout-in-place liners Any Any No 8 hrs Yes Yes Yes Yes 

Cementitious coatings, spincast 8”-12 ft Any No 2 hrs Yes Yes Yes Yes Cementitious coatings, sprayed Any Any No 2 hrs Yes Yes Yes Yes 

Coatings, epoxy Any 

(sprayed) Any No 2.5-6 hrs Yes Yes Yes Yes 

Coatings, polyurethane/polyurea 

Any 

(sprayed) Any No 1⁄2 -1 hr Yes Yes Yes Yes 

Coatings, modified polymer skin panels 

Any 

(sprayed) Any No 1 hr No Yes Yes Yes 

Flood grouting Any Any No 8 hrs No No Yes No 

Dish inserts, Grade rings Any NA No Varies No No Yes Localized 

Chimney seals, mechanical Any NA No Varies No No Yes Localized 

Chimney seals, CIP Varies 2-3 ft a No Varies No No Yes Localized 

Chimney seals, polymer Varies NA No Varies No No Yes Localized Barrel joint seals, mech., cementitious, polymer Varies NA No Varies No No Yes Localized 

Channel inserts Any NA No Varies Yes No Minor Localized 

(a) 5” into the cone. 
 

 

 

 

6.1 

6.0 EMERGING AND NOVEL TECHNOLOGIES 

In this section, a series of emerging technologies or technological/management advances that will assist in 

the effective rehabilitation and management of water and wastewater systems are highlighted and other 

potential advances are discussed. Emphasis will be placed on those technologies that are new or 

emerging in U.S. applications. 

Potential Technology Candidates for Demonstration 

Tables 10, 11, and 12 provide a list of those technologies that are considered potential candidates for 

demonstrations. The suitability of these technologies for demonstration in terms of their stage of 

development and their potential breadth of application were discussed during the International 

Technology Forum. 

Table 10. Novel and Emerging Trenchless Pipeline Rehabilitation Methods 

Method 

Example 

Technology Area of Innovation 

Diameter 

Range 

Repair 

Length Application 

Relining 

Spray liningESL Copon Hycote 

(E. Wood) 

High build epoxy for semistructural renovation, bridge 

holes 

4” - 12” 500’ Water pipe 

(AC/ferrous) 

Spray lining – 

PSL 

Heitkamp Polyurethane lining cures in 

30 min., outage reduced to 6 

hours 

4” - 12” 500’ Water pipe 

(ferrous) 

CIPP, inversion Iplus 

CompositeTM 

(Insituform) 

Composite liner 

(carbon/fiberglass) resulting 

in thinner tube, started in 

2005 

24” - 84” 1,000’ Sewer pipes, 

gravity 

CIPP, pulled in AquaPipe® 

(Sanexen) 

Robotic reinstatement of 

services, in U.S. since 2005, 

NSF 61 Listing 

6” - 12” 500’ Water pipes 

CIPP, pulled in Blue-TekTM 

(Reline America) 

Factory pre-impregnated, UV 

cured, in U.S. since 2005. 

Working on the applicability 

in water pipelines. 

4” - 48” 1,000’ Sewer pipes, 

gravity or 

pressure 

Hose Liningnon adhesive 

back 

ThermopipeTM 

(Insituform) 

Thin PE liner reinforced with 

woven polyester fiber. Rated 

to 150 psi. 

3” - 12” 700’ Water or 

sewer pipes, 

pressure 

Compression 

symmetrical 

pipe reduction 

Rolldown 

PolyFlexTM, 

(Insituform) 

HDPE pipe pulled in with 

diameter reduced up to 20% 

(round shape), in U.S. since 

2006 

4” - 48” 800’ Water pipes 

Grout-in-place MainSaverTM Composite liner (MDPE liner 

pulled in, cement grout in 

annular space), in U.S. since 

2006 

4” - 12” 350’ Water pipes 

39
 
 

 

 

 

 

 

Table 10. Novel and Emerging Trenchless Pipeline Rehabilitation Methods (Continued) 

Method 

Example 

Technology Area of Innovation 

Diameter 

Range 

Repair 

Length Application 

Close fit PVC DuralinerTM 

(UGSC) 

Expansion of PVC pipe to 

form close fit reorients 

molecular chain increasing 

strength, NSF 61 Listing 

4” - 30” 1000’ Water pipes 

Grout-in-place Trolining® Composite liner (HDPE liner 

pulled in, cement grout in 

annular space), in U.S. since 

2005 

6” - 120” 650’ Sewer pipes, 

gravity 

Sliplining, 

continuous 

Fusible C900TM 

(UGTC) 

PVC pressure pipe butt fused 

and pulled into host pipe 

6 - 36” 3000’ Water pipe, 

pressure 

Sliplining, 

segmental 

Push-and-Drive 

(IPEX/TT 

Technologies) 

PVC pipe pulled in place, 

close fit, coming on the 

market soon 

6” - 12” 500’ Sewer pipes, 

gravity 

Sliplining, 

segmental 

Channeline FRP panels usually 3’ or 6’ 

long, for man-entry pipes, 

tongue-and-groove or belland-spigot, was offered in 

U.S. 2002-2005 (Hobas) 

36” - 20 ft No limit Sewer pipes, 

gravity 

Spiral Wound SPR 

(Sekisui) 

PVC spiral-wound, in U.S. 

since 2005 

36” - 12’ x 

15’ and 

larger 

1,000’ Sewer pipes, 

gravity 

Pipe Replacement - online 

Pipe Bursting/ 

Splitting 

Impactor® 

(HammerHead) 

Merging of pipe bursting with 

HDD for faster replacement 

and less excavation (in U.S. 

since 2002), upsizing by 25% 

possible 

4” - 48” Over 

3,000’ 

Sewer and 

water pipes 

Pipe Replacement - offline 

Direct PipeTM 

Hybrid 

(Herrenknecht) HDD/Pipe jacking hybrid. 

Novel system to thrust pipe by 

external gripping. 

8” - 144” 700’ Sewer pipes, 

gravity and 

pressure pipes 

Horizontal 

Directional 

Drilling (HDD) 

for on-grade 

sewer 

Various Directional drilling with 

HDPE or PVC pipe pulled 

into hole during pull back. 

Mature for water applications, 

emerging for on-grade sewer 

applications 

4” - 54” 3000’ Water pipes, 

pressure and 

gravity sewer 

with sufficient 

grade 

tolerance. 

Flood Grouting 

Flood grouting Sanipor® Simultaneous 

main/manhole/lateral sealing, 

limited use in U.S. 

Any No limit Sewer pipes, 

gravity 

Note: Refer to Tables 7, 8 and 9 for a more complete listing of technologies. This table only lists some technologies 

that are considered more novel or still emerging in the U.S. market. 

40
 
 

 

 

 

Table 11. Novel and Emerging Technologies for Manhole Rehabilitation 

Method Example Technology Technology Outline 

Relining 

Cured-in-place liners 

(CIP) 

MultiPlexx LinerTM 

(Terre Hill) 

Patented composite CIP liner (PVCP = PVC polyester) 

developed around 2002. In addition, MultiPlexx LayupTM 

is a segmented MultiPlexx LinerTM used in hard to reach 

places. 

High Build 

Polyurenthane / Polyurea 

SprayrockTM 

Innov. Painting & 

Waterproofing 

High build, quick setting sprayed polymer linings 

suitable for structural repairs as well as corrosion 

protection. 

Note: Refer to Tables 7, 8 and 9 for a more complete listing of technologies. This table only lists some technologies 

that are considered more novel or still emerging in the U.S. market. 

Table 12. Novel and Emerging Trenchless Methods for Rehabilitation of Wastewater Laterals 

Method Example Technology Area of Innovation 

Diameter 

Range 

Repair 

Length 

CIP Relining 

UV cured CIPP lateral 

liner 

InFlex LinerTM 

(Reline America) 

Factory preimpregnated, UV cured, 

in U.S. since 2007 

2”-8” 150’ 

CIPP, T-liners LMK T-Liner® Full circle mainline seal (16”) 

added, in use since 2004 

3”-6” 160’ 

Pipe Replacement 

Pipe bursting/ splitting TricTM Trenchless, 

TT Technologies 

Equipment scaled for effective use 

in laterals 

4”-8” 20’-200’ 

Chemical Grouting 

From main, long bladder Logiball Connection Long bladders, available since 2004 4”-6” 5’-30’ 

Flood Grouting 

Flood grouting Sanipor® Simultaneous main/manhole /lateral 

sealing, limited use in U.S. 

Any No limit 

Robotic Repair 

Robotic repairs Janssen Structural repair with surrounding 

soil stabilization, in U.S. since 2005 

4”-12” 2’ 

Notes: Refer to Tables 7, 8 and 9 for a more complete listing of technologies. This table only lists some technologies 

that are considered more novel or still emerging in the U.S. market. 

6.2 Cross-Cutting Innovation Potential 

As discussed in Sections 2, 3 and 4, there are many aspects pertaining to the rehabilitation of water and 

wastewater systems that are not specific to any particular technology. These issues are summarized 

below. 

6.2.1 New Materials. Most techniques could benefit from the availability of new or improved 

materials – with enhanced strength, stiffness, corrosion resistance, short installation, curing time, etc. 

Most new materials, however, would need to be applied using one of the existing approaches for creating 

a liner inside a pipe, manhole or ancillary structure. New materials using carbon nanotubes are likely to 

41
 
 

 

be too expensive for use in the wastewater industry. Clay nanotubes are much less expensive and may 

prove to have uses in wastewater rehabilitation. However, recently released work on the health effects of 

carbon nanotubes indicates that there may be long-term asbestos-type health issues if the nanotubes are 

inhaled. Geopolymers can provide a grout or concrete-like material for use in the wastewater sector that 

have rapid strength gain and much higher corrosion resistance than concrete. They represent very 

environmentally friendly materials since their principal constituent is the waste fly ash from coal-fired 

power plants. Research is underway to adapt and control the flowability, set time, curing conditions, etc., 

so that the materials can be used successfully in cast, spray or grouting operations. 

6.2.2 Wastewater Innovations. Anticipated innovations or continued technology developments 

that are specifically related to wastewater are: 

	 Enhanced understanding of realistic loading scenarios and their probabilities and risk. 

This is probably the weakest area of current design approaches for rehabilitation 

technologies. Some research is underway, but much remains to be done. 

	 Consistent design and specifications across rehabilitation technologies. Such work is 

necessary so that competing rehabilitation technologies can be fairly evaluated in terms of 

cost, risk, and performance. 

6.2.3 Water Innovations. Anticipated innovations or continued technology developments that are 

specifically related to water are: 

 Reliable liner-service connections made without excavation at each service connection 

 Service connections made using keyhole technologies where internal reconnection is not 

feasible 

 Trenchless rehabilitation and replacement of service lines without street excavation 

 Spray on structural liners 

 Thinner composite liners that reduce the amount of cross section loss 

 Methods that reduce or eliminate the need for temporary service lines. 

6.2.4 Decision Support. A utility owner must choose the appropriate range of rehabilitation 

options for any project from the wide range of possibilities described in this State of Technology Review 

Report. In addition to the performance and cost of the rehabilitation method, such decisions derive 

strongly from the utility’s overall asset management strategy, available rehabilitation technologies, and 

the assessed condition and predicted deterioration rate of the pipe or structure under consideration. 

Rehabilitation technologies include a broad spectrum of approaches that attempt to return the system to 

near-original condition and performance: 

	 A repair technique is used when the host pipe/structure is structurally sound and provides 

acceptable flow capacity. 

	 A rehabilitation technique is used where improved hydraulic conditions and structural 

strength are needed. 

	 A replacement technique is undertaken when the pipe/structure is severely deteriorated, 

and/or an increased flow capacity is needed. 

	 Choices among repair, rehabilitation and replacement also need to consider the estimated 

life cycle cost of the facility under each option. 

42
 
 

	 The asset management and condition assessment aspects of decision support are being 

evaluated elsewhere. Only the aspects that relate to choice of the rehabilitation 

technology will be discussed here. 

The following are the key issues: 

	 For water and wastewater systems, the current system goals, existing pipe/structure 

condition, corrosion level and flow quality must be known in sufficient detail to address 

and determine whether a structural, hydraulic and/or a water quality problem exists. 

	 For wastewater systems, the above determination may depend on the planned phasing of 

work across the system and whether consent decrees with time limits for I&I reductions 

are in effect. For example, a grouting program to reduce I&I may provide immediate I&I 

relief at a reasonably low cost, permitting a less hurried approach to sector-by-sector 

evaluation and rehabilitation. 

	 Site and soil conditions, neighboring structures, geometrical configuration, and structural 

condition of the host pipe will limit the choices of the renewal technologies applicable to 

any particular project. 

	 While an engineer experienced in water or wastewater renewal could quickly arrive at the 

appropriate set of technologies that are applicable, this step can take considerable amount 

of research and effort for designers that are not familiar with all of the available 

rehabilitation technologies. Also, an experienced engineer may be unfamiliar with new 

technologies that are just being introduced. 

	 The selected technologies and materials must be acceptable to the utility. 

	 Once the applicable technologies have been narrowed to an acceptable list, organizations 

must be able to be competitively bid on a level playing field in terms of specifications, 

and there should be a reasonable likelihood of available bidders for each technology. 

Some decision support software is already available to assist in this process (Matthews and Allouche, 

2007), but significant refinements are possible that, for example, could directly import condition 

assessment information and incorporate system-wide preferences into job-by-job selections. Selection of 

current renewal techniques should be based on the structural, hydraulic, joint leakage, or water quality 

problems of the main. As part of the project, additional information will be collected: (1) to identify the 

decision criteria used by each utility for choosing water and sewer main pipes for repair, rehabilitation, or 

replacement; and (2) to obtain descriptions of the technologies previously selected and the reasons for 

their selection. For water systems, based on the AWWA M28 Manual (AWWA, 2001b), the key 

elements of a decision model to renew a structurally deteriorated pipe must include: 

(1) The exact nature of the problem 

(2) The hydraulic and operating pressure required for the rehabilitated main 

(3) Materials, geometry and dimensions of the main 

(4) Types and locations of valves, fittings, and service connections 

(5) Length of time for which the main can remain out of service 

(6) Site-specific factors 

An example of a decision tree for the rehabilitation/replacement of a structurally deteriorated water pipe 

is shown in Figure 4 (AWWA, 2001b). 

43
 
Figure 4. Selection of Rehabilitation Techniques to Solve Structural Problems [AWWA, 2001b] 

It is proposed that a multi-criteria evaluation methodology be used for an enhanced decision-making 

process. Multi-Criteria Evaluation (MCE) is a set of procedures designed to facilitate decision-making. 

The basic purpose is “to investigate a number of choice possibilities in the light of multiple criteria and 

conflicting objectives” (Voogd, 1983). The objective of a multi-criteria methodology is to find the proper 

balance of repair, rehabilitation, and replacement options and to select the “best” option and/or a ranked 

order of options. “Best”, in this context, could be interpreted as a function of the condition improvement, 

cost effectiveness, water quality, practicality, degree of disruption, risk reduction, and other criteria. 

Figure 5 shows a conceptual framework for selecting appropriate technologies. 

44
 
PROBLEM 

DEFINITION 

SYSTEM 

PROBLEMS 

SYSTEM 

CAUSES 

RENEWAL 

METHODS 

AVAILABLE 

TECHNOLOGY 

Capacity

Related 

Structural 

Related 

Other issues 

NonCompliance 

Condition & 

Performance 

Failure 

Consequence 

Internal 

Causes 

External 

Causes 

Others 

Repair 

Rehabilitation 

Replacement 

Capabilities 

Limitations 

Renewal Cost 

Condition & Performance 

Assessment 

Evaluate Rehabilitation 

Technologies 

Figure 5. Conceptual Framework for Selecting Appropriate Technologies 

6.2.5 Accelerating Adoption of New Technologies. Technologies with a clearly recognized 

advantage over existing methodologies will eventually be embraced by both industry and the owners. 

However, the advantage of a proactive approach to evaluating and introducing technologies is to shorten 

the timeframes for adoption of beneficial technologies and reduce failures during the commercialization 

process. The pitfalls for a new technology on the way to commercial success are extensive and will not 

be re-examined in detail in this State of Technology Review Report. The major pitfalls include: 

	 Initial application(s) attempted are not successful, although the method could have been 

successful under less challenging conditions and the same challenging conditions could 

have been mastered later in the product life cycle. 

	 Overcoming experience requirements, owner conservatism, competing industry 

resistance, etc. 

	 Overselling the technologies leading to inappropriate applications and failures 

	 Developmental and testing costs exceed the ability of the technology developer to 

underwrite and sufficient external investment is not raised. 

	 Technology is under capitalized, i.e. with insufficient funding to survive the market 

introduction process whereby the product must be accepted more-or-less on an owner-byowner basis across the country. 

45
 
There are many facets to the introduction of a new technology to water and wastewater industry, whether 

invented from scratch or being introduced from another industry or country. Appropriate specifications 

and standards must be created, local technology demonstrations typically are required, standard and 

specialized testing (short- and long-term) will need to be conducted or evaluated by organizations 

accepted by the owners, and cost and performance data prepared to show the benefits of the new 

technology. 

It is possible, however, for government and other organizations to greatly assist in the process of speeding 

up technology introductions and reducing unnecessary and duplicative costs for the technology 

developers. The following are some examples of programs that have proved successful in assisting the 

technology introduction process. 

EPA Environmental Technology Verification (ETV) Program. The ETV program was developed by 

EPA to provide a voluntary but consistent methodology whereby new technologies could establish their 

environmental performance. The technology can then be “verified” as meeting this standard of 

performance which helps to overcome some of the barriers to introducing novel technology. 

Civil Engineering Research Foundation (CERF) Program. During its years of operation, CERF 

developed an exemplary technology evaluation program to help bring new technologies to the 

marketplace. Key aspects of the program included a review panel drawn from major potential users of the 

technology, and support from an expert consultant or organization. The panel developed the testing 

program and reviewed the results that were executed by the company and the consultant. 

California Pipe Users’ Group. It is typically far more efficient for both the potential users of new 

technologies and for their developers to carry out new product assessment activities in a group setting. 

The appropriate personnel in a variety of user organizations and their consultants can share application 

information and develop consensus approaches to new product acceptance. 

Trenchless Technology Municipal Users’ Forum Program. In a similar fashion to the California Pipe 

Users’ Group, the TTC at Louisiana Tech University organizes local/regional forums across the country 

which is designed to stimulate the sharing of information among the potential users of trenchless 

technologies. Successes and problems can be shared leading overall to a higher effectiveness for 

rehabilitation efforts. 

Center for Innovative Grouting Materials and Technology (CIGMAT), University of Houston. 

CIGMAT has been active in research and testing related to buried piping systems for more than a decade. 

It has been a active partner in the development of test protocols for use in the EPA Environmental 

Technology Verification program. 

The University of Louisville Center for Infrastructure Research. The center was formed in August 

2002 through a partnership between the University of Louisville, the Metropolitan Sewer District and the 

Louisville Water Company. The intent of the center is to leverage the limited resources of these sponsors 

and additional sponsors to solve common problems and then to disseminate the learned information. 

Accelerated Pavement Testing Programs. Accelerated Pavement Testing (APT) programs have been 

conducted by State Departments of Transportation (DOTs) across the country. DOTs have gained 

immensely by instituting such APT programs that particularly have made significant headway in terms of 

quantifying pavement performance characteristics under various field conditions. Florida DOT in 

particular has an exemplary APT program. This model could be adapted to develop a program. 

46
 
EPA Science To Achieve Results (STAR) Program. The STAR program targets the encouragement of 

research to advance environmentally related technologies with a mission to include U.S. universities and 

non-profit groups in the EPA research program to ensure the best possible quality of science in areas of 

highest risk and importance to EPA. Sub-programs include: targeted research grants, exploratory 

research grants, graduate fellowships and research center competitions. 

Small Business Innovation and Research (SBIR) Grants. The SBIR program targets assistance to small 

businesses in conducting research and developing technological innovations. Similar programs are 

operated by many federal agencies and they also encourage the collaboration of small business with 

academic researchers. 

AwwaRF/WERF Research. AwwaRF and WERF have sponsored relevant research and field 

demonstrations in this area. For example, a field demonstration program was held to evaluate various 

trenchless technologies as alternatives to open-trench rehabilitation and replacement of water mains. The 

objective was to identify conditions under which each technology could be best applied (Deb et al., 1999). 

6.2.6 Observations on Successful Programs. The programs above address issues involved in 

gaining the approval for the use of a new technology and expanding its marketplace of application by 

providing: 

 User input for defining the standards that new technologies must meet before they are 

considered acceptable 

 Independent verification of the claims of technology developers 

 Sharing of information about new technologies among peer user groups 

 Accessing the talents and resources of the nation’s universities 

 Easing the financial burden on a technology developer in bringing a new product to 

geographical and organizational diverse market. 

47
 
 

 

7.0 EPA DEMONSTRATION PROJECTS 

7.1 Purpose of Technology Demonstration 

As discussed in the previous sections, the water infrastructure in the U.S. is deteriorating at an 

accelerating rate. Some important factors behind the deterioration are reduced funding, poor installation 

resulting from insufficient QC, little or no inspection and maintenance, and a general lack of uniformity 

and improvement in design, construction, and operation practices. To meet the challenge of ongoing and 

increasing needs for maintenance and repair of the water and wastewater systems, many utilities are 

seeking innovative technologies to replace, renew, or extend the life of their systems, and to meet more 

stringent regulatory requirements. Unfortunately, information on new and emerging technologies is not 

always readily available or easy to find, especially when applied under actual field conditions. 

Lack of knowledge on the performance of innovative and emerging rehabilitation technologies and the 

limited ability to determine the most cost-effective, long-term rehabilitation methods for water 

distribution and wastewater collection systems were identified as critical gaps by the key stakeholders 

participating in the March 2006 EPA Workshop on Innovation and Research for Water Infrastructure for 

the 21st Century (EPA, 2006a). To help fill these gaps, a demonstration program on emerging and 

innovative rehabilitation technologies was proposed, in collaboration with water and wastewater utilities, 

to gather reliable performance and cost data during applications of these technologies under a wide range 

of field conditions (EPA, 2007b). 

Demonstration of emerging and innovative rehabilitation technologies at selected sites in the U.S. can 

make the capability of these technologies better known to the water and wastewater industry, allowing 

their applications to be promoted in the U.S. The impartial assessment on the effectiveness, longevity, 

expected range of applications, and life-cycle cost of the demonstrated technologies can assist the utilities 

in determining whether rehabilitation or replacement is more cost effective and in selecting which 

rehabilitation technology to use. 

7.2 Previous Demonstration Projects and Benefits of Demonstration. There are many case 

studies and laboratory-scale and pilot-scale evaluations on innovative and emerging rehabilitation 

technologies and materials (EPA, 2006b), but only a handful of field demonstration projects have been 

conducted to date. Two examples are illustrated below: 

	 Demonstration of Innovative Water Main Renewal Techniques. The AwwaRF 

sponsored this field demonstration project in 1999 to evaluate three trenchless 

technologies for water main renewal and identify conditions under which each 

technology could be best applied (Deb et al., 1999). It successfully demonstrated a pipe 

bursting technology to burst an existing 6-inch CI pipe and replace it with an 8-inch DI 

pipe (i.e., a bell-less microtunneling push pipe). 

	 Demonstration of Decision Support Tools. Computer Aided Rehabilitation of Sewer 

Networks (CARE-S) and Computer Aided Rehabilitation of Water Networks (CARE-W) 

are European Commission-developed rehabilitation decision support systems that have 

been adapted by water utilities to set up strategic and tactical rehabilitation plans. It is 

important to evaluate the applicability of these tools in a range of utility types and sizes 

and optimize data collection. Researchers at the Polytechnic University of New York 

recently conducted a demonstration project of CARE-W at Las Vegas to develop a costeffective system for maintaining and repairing the water distribution networks. The 

project has developed performance indicators, a failure forecasting model, a hydraulic 

48
 
reliability model and long term economic simulation tools, and an annual rehabilitation 

planning program (Vanrenterghem-Raven, 2007). 

From these and other past demonstration projects, it suggests that well documented and publicized 

demonstration projects by credible organizations can play an important role in accelerating development, 

evaluation, and acceptance of new technologies. A successful demonstration project will not only 

generate good quality data, which is useful to the research communities, but also provides substantial 

value to the utilities, manufacturers/technology developers, and consultants/service providers. The 

benefits of the technology demonstration to these various groups are summarized below: 

	 Benefits to Utilities 

o	 Reduced risk of trying new technologies and new materials on their own 

o	 Increased awareness of emerging technologies, particularly those from overseas, and 

their capabilities 

o	 Assistance in setting up strategic and tactical rehabilitation plans 

o	 Identification of regulatory and quality control issues. 

	 Benefits to Manufacturers/Technology Developers 

o Opportunity to advance technology development and commercialization 

o Opportunity to accelerate the adoption of new technologies in the U.S. 

	 Benefits to Consultants and Service Providers 

o	 Opportunity to compare performance and cost of similar products in a consistent 

manner 

o	 Access to standards and specifications for the new techniques 

o	 Education of best practices on pre- and post-installation procedures and testing 

7.3 Special Aspects of Planned EPA Demonstration Project 

While the technology demonstration project is intended to evaluate the capability and performance of the 

technology, it also provides an opportunity to address/examine several key issues identified in Sections 2, 

3, and 4. Special aspects of the EPA demonstration project are discussed below, aiming to bring added 

value to the water and wastewater rehabilitation industry within a five to 10 year timeframe. 

7.3.1 Demonstrate Application of Consistent Design Methodologies and Decision Support 

Approaches to the Selected Technologies. The need for consistent design methodologies and decision 

support approaches for different rehabilitation systems is discussed in previous sections. Because of the 

rapid evolution of rehabilitation technologies, standards and codes often lag behind, which poses a great 

challenge to the design work. Types of qualification testing and consistent test protocols for the selected 

technologies are also needed to ensure conformance of the rehabilitation technology to the specifications. 

Standards and Codes of Practice do exist overseas and the adaptation of these measures to the North 

American market is one way to quickly advance the development of standards and codes. An important 

role of the EPA demonstration project is to identify/develop common specifications for the selected 

technologies and apply consistent design methodologies based on the specifications. It may require 

collaborations with organizations such as NASSCO, ASTM, Water Environment Federation (WEF), and 

ASCE in identifying and developing the specifications. 

7.3.2 Demonstrate Application of Appropriate QA/QC and Post-Installation Procedures. The 

success of a rehabilitation project depends largely on the proper installation controls and post-installation 

inspection and assessment. The level of the qualification testing and QA requirements vary from 

technology to technology; sometimes there is no clear industry quality standard. The demonstration 

49
 
project provides an opportunity to examine the current QA practices and identify areas for improvement. 

For the technologies lacking an industry quality standard, QA/QC procedures developed by the 

manufacturers and utilities shall be reviewed and adopted (as appropriate) to the demonstration project. 

The demonstrations will allow the QA/QC protocols to be tested. 

Post-installation tests range from taking samples from finished installation for mechanical properties 

testing, air-pressure testing, water exfiltration testing, to non-destructive testing (NDT) using CCTV and 

ultrasonic technologies. Preferences shall be given to NDT approaches for the demonstration project. 

Some rehabilitation technologies do have reasonable QA testing specifications; however, system owners 

often do not execute them at the end of the rehabilitation because they assume design performance can 

always be achieved. The process to identify installation deficiencies through application of QA protocols 

will be documented through the demonstration project, which can be useful to educate the utility owner of 

the importance of good QA practices for an effective rehabilitation. 

7.3.3 Demonstrate Life-Cycle Plan for Ongoing Evaluation of Rehabilitation Performance. 

Data on the long-term effectiveness and longevity of rehabilitation technologies are difficult to obtain 

from the field demonstration directly due to the short timeframe of the project versus the long service life 

of many rehabilitation technologies, i.e., the design life for CIP liners is estimated to be 50 years or more 

(WERF, 2006). It is important for the demonstration project to lay the groundwork by assisting the 

utilities in developing a life cycle plan for ongoing evaluation of rehabilitation performance. For 

example, the project shall collect relevant environmental and performance data before and immediately 

after rehabilitation (e.g. water quality in water systems or infiltration estimates in sewer systems) to 

provide a baseline for long-term evaluation. Many operational and environmental factors, such as soil 

conditions, stress conditions, groundwater levels, sewage/soil acidity, and dissolved oxygen levels for 

wastewater and water quality for water, may have negative impacts on the effectiveness and longevity of 

rehabilitation. It is important to characterize these factors on a long-term basis. 

Indirect metrics, such as long-term laboratory coupon tests and accelerated aging tests combined with 

model simulation, may be useful in evaluating the long-term effectiveness of new materials/ technologies. 

Recommendation and suggestions were solicited from the Forum participants to identify additional 

metrics to assess the long-term effectiveness of rehabilitation technologies. 

7.3.4 Document Data from Demonstration. The demonstration project shall collect the 

following data/information at each demonstration site: 

	 Installation process, procedures, and problems encountered 

	 Performance data: collect short-term data and establish procedures for tracking long-term 

effectiveness, and projected longevity 

	 Labor requirement and cost information for conducting demonstration, including design, 

capital, and O&M costs 

	 Comments and feedback from utility owners and consultants 

Such information will be included in a project report available to the project participants. 

7.3.5 Provide an Assessment of Selected Technology, Expected Range of Applications, 

Avenues for Improvements. The demonstration project will assess the short-term and long-term 

effectiveness and life-cycle cost of the selected technologies in comparison with the respective vendor 

specifications and identify conditions under which each technology can be best applied. It will also 

50
 
 

 

provide suggestions on necessary improvements for the technology itself, the installation procedures, and 

QA/QC procedures. The expected range of applications claimed by technology vendors can be verified 

based on demonstration results of a single technology at multiple sites. 

7.4 Demonstration Approach 

One key objective of the International Technology Forum was to solicit input from the participants on the 

technical approaches for conducting the demonstration project. This section provides a basis for 

discussion at the Forum. The input from the Forum participants is summarized in Section 8. 

7.4.1 Technology Selection Criteria. The term “innovative technologies” includes innovative 

designs, components, systems, methods, and procedures. The technology selection criteria may vary with 

respect to different types of technologies, but shall follow the general guidelines below: 

	 Performance. This criterion will be evaluated based on capabilities and limitations of 

the technology, the advances over existing and competing technologies, the strength of 

supporting performance data (full-scale data carry more weight than pilot-scale data), 

feedback from previous installation sites, and patent citation, if applicable. The potential 

of the proposed technology as a compliance strategy for the specific conditions should be 

identified. Third party evaluations and appropriate QA information are important 

components of the supporting data. 

	 Cost – Direct and Indirect Cost. A critical factor in the evaluation of technologies is 

the cost of installation (direct cost) and cost for periodic inspection and cleaning (indirect 

cost). The typical installation cost on a per-unit basis (i.e., cost per linear foot) shall be 

provided. Warranties or guarantees on performance should be provided. Tracking social 

costs such as the disruption of traffic is beyond the scope of this study. 

	 Complexity. The complexity of the technology refers to the level of training required for 

the installer, pre- and post-installation requirements, and maintenance requirements. An 

estimate of the time and cost for maintenance should be provided. 

	 Maturity. Depending on the stage of development for each technology, it can fall into 

developmental/emerging, innovative, or established category. New technologies that are 

commercially available overseas, but not yet widely applied in the U.S. market, are 

considered to be emerging with respect to U.S. applications. 

	 Potential Benefits. Potential benefits gained from implementing a rehabilitation 

technology may include capital savings, operational savings, I&I reduction, SSO/CSO 

reduction, restored structural integrity, leakage reduction, and improved maintenance 

tracking/management, etc. Technologies with a high potential to improve a utilities’ 

ability to cost-effectively repair, rehabilitate, or replace water mains and sewers have the 

greatest benefits. 

Efforts were made to solicit candidate technologies at an international level through the Technology 

Forum input, via a comprehensive literature search, and through member societies of the International 

Society for Trenchless Technology (ISTT). This generated a list of candidate technologies that will 

continue to be updated with input and feedback from EPA, the project stakeholder group, and Forum 

participants. The final selection of the demonstration technologies will be made jointly by EPA, a peerreview expert panel, and the demonstration host sites. 

7.4.2 Site Selection Criteria. To ensure the field demonstration results are acceptable and useful 

to the user community, the selected demonstration scenarios must be representative of typical applications 

51
 
 

for a given technology. The environmental conditions (i.e., soil, groundwater, and surface conditions) of 

the host sites also shall be representative. Another key criterion in site selection is the utilities’ 

willingness to participate, which depends largely on their needs to improve their water or wastewater 

systems, their understanding of present problems, their time and resources available to contribute, and 

their desire to advance the state of the technology. Decisions will also depend on the receptivity of the 

corresponding city/county for demonstration and the accessibility of the potential demonstration sites. 

The following factors shall be considered in developing site selection criteria: 

 Utilities’ willingness to participate 

 Known problems with water and/or wastewater systems 

 Maintenance and operation history 

 Pipe age 

 Pipe sizes and materials 

 Site accessibility, including traffic control requirements 

 Security of testing equipment/instrument 

 Local hydraulic and soil conditions 

 Technology vendor’s stated application limitations 

 CCTV or other inspection technology reports available at the site 

 Proximity of site to high-voltage power lines. These may impact some of the 

instrumentation readings 

 Proximity of site to high-pressure lines, for example natural gas, gasoline lines (mainly 

for safety considerations) 

 Proximity of site to contaminants/toxics in the soil or groundwater 

 Proximity of site to high decibel noise sources 

 Proximity of site to fault zones or active faults 

 Closeness to fire and police protection, including fire lines 

 Restrictions to access (right-of-way) 

 Receptivity of local city or county or municipality for demonstration 

 Representativeness – how typical is the field demonstration to problems commonly faced 

by most utilities 

	 Regulatory climate – how willing are local and state officials to work with the researchers 

and utility concerning requirements (NSF approval, etc.) to permit use of an innovative 

technique. 

	 Perceived value – number of interested utility participants; regional-scale versus nationalscale (e.g., value to each user times total number of users). 

	 Feasibility of measuring performance and cost – Special considerations shall be given to 

ensure that the selected site will allow evaluation of the effectiveness of the rehabilitation 

approach. For example, it is challenging to evaluate the effectiveness of a sewer lateral 

52
 
 

 

 

rehabilitation by the reduction in I&I volume. This is because in a normal practice of 

mixed mainline and laterals system, I&I volume from a specific lateral cannot be 

quantified due to the existence of other I&I sources in the system (WERF, 2006). With a 

special site that would allow temporarily (up to several hours) plugging the mainline 

upstream of the rehabilitated lateral, I&I volume from the lateral can be evaluated in a 

rainfall simulation, using a flow monitoring equipment installed in the mainline 

immediately downstream of the lateral connection (WERF, 2006). 

7.4.3 Demonstration Protocols and Metrics. The demonstration of new or emerging 

technologies will require clear and repeatable testing criteria if the new technologies are to be understood 

and eventually accepted as reliable industrial tools. Bridging the gap from prototype or bench scale 

technology performance to field performance can only be credibly accomplished if demonstration projects 

are carefully designed and executed. A demonstration protocol provides guiding principles and a 

consistent approach for conducting safe and appropriate demonstrations and documentation of 

rehabilitation technologies in a manner to encourage acceptance of the test results by water and 

wastewater utilities. 

The demonstration protocols will be specific for the chosen demonstration technologies, but also be 

general enough in nature to accommodate future technology field demonstrations. The protocols will 

have three major sections: (1) Planning, (2) Field Demonstration, and (3) Data Assessment and Reporting. 

The Planning section will include objectives of the demonstration, capabilities, features, and limitations of 

the technologies and site conditions. The Field Demonstration section will include standardized field 

testing methods and procedures for the rehab technology to be demonstrated. The Data Assessment and 

Reporting section will include specific guidelines addressing how performance and cost data are to be 

gathered uniformly and analyzed and the format of the report. The protocols will also provide specific 

guidelines for the preparation of site- or technology-specific tests plans, quality assurance project plans 

(QAPPs), and health and safety plans. 

7.4.4 Demonstration Trials. As part of the project, the field demonstration of at least two 

innovative technologies is planned to take place in 2010, which will provide an opportunity to implement 

and refine the selection criteria, protocols, and metrics developed for future large-scale demonstrations. 

Based on the Project Team’s experience and an extensive literature search, several technologies have 

been identified as potential candidates for field demonstration in three categories: pipeline rehabilitation 

(water and wastewater), manhole rehabilitation, and wastewater laterals. The preliminary list of candidate 

technologies was presented at the Forum and updated with input from the Forum participants (see Section 

6). Initial contacts with vendors and utilities have been made to solicit their interest in participating in the 

project and providing in-kind contribution for 2- or 3-day field trials held at utilities in close proximity to 

the vendors’ offices and where they have established working relationships. An alternative approach is to 

collaborate with utilities having on-going rehabilitation projects using innovative technologies where 

EPA can subsidize the testing, monitoring, QA/QC, data analysis, and reporting parts of the projects. The 

final selection of technology and host sites is yet to be made by EPA and the project stakeholder group. 

7.4.5 Invitation to Apply and Selection Process for Future Demonstration. For the large-scale 

demonstration project to be conducted in the future, it is important that the application and selection 

process be objective and transparent to the utilities and technology vendors. General approaches can be 

adopted from a large-scale EPA Arsenic Removal Technology Demonstration Program, which is being 

conducted at 50 sites in 24 states (EPA, 2008a). The invitation to apply for participation in the 

demonstration project can be announced in the Federal Register and/or the EPA website requesting 

interested water/wastewater utilities and vendors to submit Letters of Intent and technology proposals, 

respectively. The announcement should be linked to the websites of other research organizations or 

industrial trade associations (i.e., WERF, Water Research Foundation, North American Society for 

53
 
Trenchless Technology (NASTT), etc.) for additional dissemination. An independent technical panel will 

be convened by EPA to review the utilities’ information and vendors’ proposals according to the selection 

criteria discussed above and provide recommendations to EPA on the sites and technologies appropriate 

for demonstration. Depending on the funding level and other factors, multiple sites and multiple 

technologies will be selected for demonstration. 

54
 
 

8.0 FORUM OUTCOMES AND RECOMMENDATIONS 

A companion EPA report titled “Forum Report for Rehabilitation of Wastewater Collection and Water 

Distribution Systems” is available, which fully documents the Forum discussions (EPA, 2008b). The 

major outcomes and recommendations from the Forum are summarized below. 

State of Infrastructure. The consensus of the Forum was that the current state of buried water and 

wastewater assets in the U.S. continues to deteriorate. The main impediments to faster improvement were 

as follows: 

	 Increased Funding Needs. Increased funding received a high ranking from Forum 

participants. Out-of-sight and out-of-mind was seen as a political barrier to more 

funding. Utilities must use their limited existing funds for repair/rehabilitation wisely 

and improved decision tools were needed to help them make cost/benefit calculations for 

rehabilitation – especially in relation to inflow/infiltration (I/I) control. 

	 Improved Technology Needs. Better technologies received a medium to high ranking 

from Forum participants. It was indicated that technology needs were especially high for 

water pipeline rehabilitation. It was also suggested that vendors should demonstrate their 

technologies up front to meet the pre-qualifying needs of utilities. 

	 Improved Training and Education. Improved training needs and education received a 

medium to high ranking. Participants are looking for increased information and 

knowledge sharing about rehabilitation technologies. They would place extra weight on 

evaluation data from an independent source. Participants also suggested that a “lessons 

learned” central database be developed on rehabilitation technologies. 

	 Increased Staffing Needs. Increased staffing needs received a low to medium ranking. 

Participants recognized the challenge of ageing professional staff and the need for 

increased recruitment and professional education. In large part, staffing needs would be 

expected to be resolved with adequate funding, although the shortage of civil engineering 

professionals impacts the availability of appropriate staff. 

State of Technology Review Report Review. The Forum participants suggested some changes to the 

content of the State of Technology Review Report as summarized in this report, but there were no major 

disagreements with the overall sense of the State of Technology Review Report. Written comments were 

received from stakeholders and Forum participants and incorporated into the Final State of Technology 

Review Report as appropriate. 

State-of-Technology (SOT) and Key Rehabilitation Issues. Forum participants shared case studies and 

information on emerging, innovative, and international rehabilitation technologies for water and 

wastewater. These additional technologies were reviewed for inclusion in the State of Technology 

Review Report. Specific needs were identified on how to increase adoption and overcome barriers to the 

use of innovative rehabilitation technologies. A few of these needs are listed below: 

	 Operation and Maintenance (O&M) Needs. Addressing concerns associated with 

ongoing O&M needs is crucial for a wider acceptance of rehabilitation methods. 

Rehabilitation technologies need to include how to maintain and repair restored piping. 

Repairs of rehabilitated pipelines need to be performed by the utilities' regular 

maintenance crews. 

55
 
 

	 Challenging Pipe Configurations. Wastewater rehabilitation faces several challenges 

with difficult pipe configurations such as large diameter, non-circular sewers with angles 

and bends that can be rehabilitated while remaining in service. 

	 Disinfection and Service Reconnections. Water main rehabilitation will continue to lag 

sewer rehabilitation in the U.S. unless practical solutions can be developed for addressing 

rapid disinfection and customer service reconnections of rehabilitated piping. 

	 Design and Quality Assurance/Quality Control (QA/QC). A systematic approach to 

design and QA/QC is lacking in the rehabilitation industry. There is a great need for 

collecting, analyzing, and publicizing performance information which will provide a 

strong incentive for QA/QC at all levels (i.e., design, manufacturing, and installation). 

Cost-effective methods and protocols for collecting quantitative in-situ data regarding the 

baseline (initial) performance of the rehabilitated pipe are critical and will facilitate the 

establishment of successful installation QA/QC and long term performance monitoring 

programs among utilities. Better inspection and assessment methods of the rehabilitated 

pipe are crucial for a wider acceptance of water and force main rehabilitation methods. 

	 Need to Integrate Sustainable/Green Technology Concepts. It is not enough to repair or 

rehabilitate one pipe. A watershed-based, system-wide approach should be adopted as 

part of the decision-making process, especially for I/I control issues. Research should 

look at the integration of green and grey water technologies. Trenchless rehabilitation 

technologies can often reduce the overall “carbon footprint” of a construction project 

and/or reduce overall impacts to the environment and indirect costs to the community. 

Rehabilitation Information and Knowledge Sharing. There is a desire for EPA to become or facilitate a 

technology transfer center for rehabilitation technologies with the ability to provide information on 

emerging technologies as well as existing technologies. Information must be sufficient enough to allow 

for a clear understanding of these technologies including proper application parameters and demonstrated 

life-cycle information. The EPA could provide impartial information based on pre-requisite technical 

data and field performance. 

Technology Demonstrations. A technical panel of vendors and utilities was invited to provide feedback 

on how to conduct the field demonstration of emerging and innovative rehabilitation technologies in order 

to maximize benefit to the user community. The vendor and utility panel and group discussions led to 

several conclusions. A few of these are summarized below: 

	 Demonstration Impact and QA/QC Protocols. Demonstrating only a handful of novel and 

emerging technologies is going to have only a limited impact. The demonstrations need 

to have a broader impact (e.g., on design and QA/QC practices) rather than just showing 

that a technology can be successfully installed. 

	 Technology Selection Criteria. Forum participants indicated several criteria that should 

be considered for inclusion of a technology in an EPA Demonstration Program including 

emerging technologies which are commercially-ready; adaptability and widespread 

benefit for small- to medium-sized utilities; ease of installation; truly novel and more than 

incremental improvement over conventional methods; environmentally-friendly; and used 

to reduce frequency of breaks for water utilities. 

	 Technology Performance Metrics. Forum participants indicated several metrics that 

should be used to document rehabilitation system performance including unit cost of the 

technology application; installation time and social disruption; QA/QC plan and outcome; 

56
 
manufacturer stated performance versus actual performance; durability; physical strength; 

visual appearance; flow properties and friction factors; and I/I reduction for sewers. 

	 Controlled Technology Performance Assessment. Results from controlled technology 

performance assessment via the development of a test bed would reduce the perceived 

risk to municipal engineers. When trying a new technology, often these engineers are 

expected to assume the entire risk, putting their reputation and budget on the line. There 

was great interest among the participants in the presentation on Germany’s Institute for 

Underground Infrastructure (IKT) which conducts controlled performance trials for 

rehabilitation vendors including a “Consumer Reports” type testing for sewer lateral 

rehabilitation technologies. 

Long Term Performance Assessments of Rehabilitation Projects. There was a strong feeling that 

revisiting previously installed rehabilitation projects with a detailed investigation and estimation of 

deterioration versus as designed and installed condition would be valuable (despite the expected lack of 

post-installation data). Long-term data regarding the performance of various rehabilitation systems is 

badly needed; the availability of such data will enable decision makers to make fully informed costbenefit decisions. 

Rehabilitation Decision-Making Tools. Utilities at the Forum expressed an interest in sharing 

information on how they make decisions regarding the replacement versus rehabilitation of their 

wastewater collection and/or water distribution systems. Of particular concern was how to estimate the 

cost/benefit for I/I reduction projects achieved from rehabilitation. The project team will collect case 

study information from 10 to 15 utilities on their rehabilitation prioritization approaches and decisionmaking methodologies. The resulting case study report will build on existing decision models for water 

and wastewater utilities. A generalized methodology will be developed based on these case studies, along 

with recommendations for improvements to current practices. 

57
 
9.0 REFERENCES 

Allouche, E.N., S. Alam, I. Juran, and R. Sterling, 2009. “Hot Sewers: Experimental Evaluation of CIP 

Lining Systems for High Temperature Applications in Sewer Pipes,” to appear in the 

Proceedings of No-Dig International Conference, Toronto, Canada, April. 

ASCE, 2007. Infrastructure Report Card, American Society of Civil Engineers, Reston, VA. 

AWWA, 2001a. Dawn of the Replacement Era: Reinvesting in Drinking Water Infrastructure, American 

Water Works Association, Denver, CO. 

AWWA, 2001b. Rehabilitation of Water Mains (M28) 2nd Edition. American Water Works Association, 

Denver, CO. 

AWWA, 2004. Water Stats 2002 Distribution Survey. American Water Works Association, Denver, CO. 

AWWA, 2008. C620-07 Spray-Applied In-Place Epoxy Lining of Water Pipelines, 3 In. (75 mm) and 

Larger. American Water Works Association, Denver, CO. 

Burn, S., 2006. Long-Term Performance Prediction for PVC Pipes, American Water Works Association 

Research Foundation, Denver, CO. 

Davis, P, S. Burn, and S. Gould, 2008. Long-Term Performance Predictions for PE Pipes, American 

Water Works Association, Denver, CO. 

Deb, A.K., Y.K. Hasit, and C. Norris, 1999. Demonstration of Innovative Water Main Renewal 

Techniques. AwwaRF. Denver, CO. 

EPA, 2002. The Clean Water and Drinking Water Infrastructure Gap Analysis. U.S. Environmental 

Protection Agency. Office of Water, Washington, D.C. 

EPA, 2003. Drinking Water Infrastructure Needs Survey and Assessment, U.S. Environmental Protection 

Agency. Office of Water, Washington, D.C. 

EPA, 2006a. Innovation and Research for Water Infrastructure for the 21st Century – EPA Research 

Planning Workshop – Draft Meeting Report. U.S. Environmental Protection Agency, Office of 

Research and Development – National Risk Management Research Laboratory, Cincinnati, OH. 

EPA, 2006b. Emerging Technologies for Conveyance Systems New Installations and Rehabilitation 

Methods. EPA 832-R-06-004. U.S. Environmental Protection Agency, Office of Wastewater 

Management, Washington, D.C. 

EPA, 2007a. Innovation and Research for Water Infrastructure for the 21st Century – Research Plan, 

U.S. Environmental Protection Agency, Office of Research and Development – National Risk 

Management Research Laboratory, Cincinnati, OH, April. 

EPA, 2007b. Performance Work Statement – TO 58, U.S. Environmental Protection Agency, Office of 

Research and Development – National Risk Management Research Laboratory, Cincinnati, OH. 

EPA, 2008a. Arsenic Research Web Page. Office of Research and Development – National Risk 

Management Research Laboratory, Cincinnati, OH. Available at: 

http://www.epa.gov/ord/nrmrl/wswrd/dw/arsenic/. 

EPA, 2008b. Forum Report for Rehabilitation of Wastewater Collection and Water Distribution Systems 

(Draft). U.S. Environmental Protection Agency. December. 

Federal Register, 1994. Combined Sewer Overflow Control Policy; Notice. Volume 59, No. 75. April 19. 

58
 
 

Gilchrist, A. and E.N. Allouche, 2005. “Quantification of Social Costs Associated with Construction 

Projects: State-of–the–Art Review,” Journal of Tunnelling and Underground Space Technology, 

Vol. 20, No. 1, pp. 89-104. 

Holme, R, 2003. “Drinking Water Contamination in Walkerton, Ontario: Positive Resolutions from a 

Tragic Event,” Water Science & Technology, Vol 47, No 3, pp. 1–6. 

Johnson, D.H., E. Levin, and J. Birdsall, 2002. “New Process for Structural Rehabilitation of Pressure 

Pipelines,” Proceedings of the No-Dig International Conference, Montreal, Canada, April, 10 p. 

Matthews, J., and E.N. Allouche, 2007. “Validation of a Decision Support System for Method Selection 

in Utility Construction,” Proceedings of ASCE Pipelines 2007, Boston, MA, July, 10 p. 

NACE, 1984. “Chapter 12-Coatings,” Corrosion Basics – An Introduction. NACE International, Houston, 

TX. 

NACWA, 2007. Priority Issues - Wet Weather Programs - Sanitary Sewer Overflow. Available at: 

http://www.nacwa.org/index.php?option=com_content&task=view&id=31&Itemid=72, accessed 

July 2007. 

Schladweiler, J., 2002. “Tracking Down the Roots of our Sanitary Sewers,” Available at: 

www.sewerhistory.org. 

Sloan, R.N., 2001. “Chapter 2 – Pipeline Coatings,” Peabody’s Control of Pipeline Corrosion, 2nd 

Edition, NACE International, Houston, TX. 

Sterling, R. L., J. Simicevic, A. Habibian, R. Nelson, R.L. Tarbutton, and A. Johnson, 2006. Methods for 

Cost-Effective Rehabilitation of Private Lateral Sewers. WERF 02-CTS-5. Water Environment 

Research Foundation, Alexandria, VA. 

Szeliga, M.J., 2007. “Analyses of Ductile Iron Corrosion Data from Operating Mains and Its 

Significance,” Proceedings of ASCE Pipelines 2007, Boston, MA, July. 

Troia, 1999. A Guide to Troia, University of Tubingen, Ege Yayinlari, Istanbul. 

Underground Construction, 2008. “Annual Market Survey,” Oildom Publishing, Houston, TX, February. 

Vanrenterghem-Raven, A., 2007. “Asset Management Best Practices: The Rehabilitation of the LVVWD 

Distribution Network Using CARE-W,” AWWA Annual Conference and Exposition, Toronto, 

Canada, June. 

Voogd, H., 1983. Multicriteria Evaluation for Urban and Regional Planning, Pion, Londres. 

WERF, 2004. An Examination of Innovative Methods Used in the Inspection of Wastewater Systems. 

WERF 01-CTS-7. Water Environment Research Foundation, Alexandria, VA. 

WERF, 2006. Methods for Cost-Effective Rehabilitation of Private Lateral Sewers. WERF 02-CTS-5. 

Water Environment Research Foundation, Alexandria, VA. 

WERF, 2008. Guidelines for the Inspection of Force Mains (Draft). 04-CTS-6UR. Water Environment 

Research Foundation, Alexandria, VA. 

59
 
APPENDIX A 

Abbreviations
 
AC asbestos cement 

ACP asbestos cement pipe 

ANSI American National Standards Institute 

APT accelerated pavement testing 

ASCE American Society of Civil Engineers 

ASTM American Society for Testing and Materials 

AWWA American Water Works Association 

AwwaRF American Water Works Association Research Foundation (changed name to Water 

Research Foundation since January 1, 2009) 

CARE-S Computer Aided Rehabilitation of Sewer Networks 

CARE-W Computer Aided Rehabilitation of Water Networks 

CCP concrete cylinder pipe 

CCTV closed-circuit television 

CERF Civil Engineering Research Foundation 

CFRP carbon fiber reinforced pipe 

CI cast iron 

CIGMAT Center for Innovative Grouting Materials and Technology 

CIP cured-in-place 

CIPP cured-in-place pipe 

CMOM capacity, management, operation, and maintenance 

CSO combined sewer overflow 

DI ductile iron 

DIPRA Ductile Iron Pipe Research Association 

DOT Department of Transportation 

EPA United States Environmental Protection Agency 

EPDM ethylene propylene diene M-class rubber 

ETV Environmental Technology Verification 

FRP fiberglass reinforced pipe 

GAO Government Accounting Office 

GASB Government Accounting Standards Board 

GIP grout-in-place 

GIPL grouted-in-place lining 

GIS geographic information system 

HDB hydrostatic design basis 

HDD horizontal directional drilling 

HDPE high density polyethylene 

I&I inflow and infiltration 

IKT Institute for Underground Infrastructure 

ISTT International Society for Trenchless Technology 

MACP Manhole Assessment and Certification Program 

MCE multi-criteria evaluation 

MCL maximum contaminant level 

MCLG maximum contaminant level goal 

A-2
 
NACE National Association of Corrosion Engineers 

NACWA National Association of Clean Water Agencies 

NASSCO National Association of Sewer Services Companies 

NASTT North American Society for Trenchless Technology 

NDT non-destructive testing 

NPDES National Pollutant Discharge Elimination System 

NPDWR National Primary Drinking Water Regulation 

NRMRL National Risk Management Research Laboratory 

NSF NSF International 

O&M operation and maintenance 

OD outside diameter 

PACP Pipeline Assessment and Certification Program 

PCCP prestressed concrete cylinder pipe 

PE polyethylene 

PINS pipeline infrastructure 

PRP polyester fiber reinforced polyethylene 

PVC polyvinyl chloride 

PVCP polyvinyl chloride polyester 

QA/QC quality assurance/quality control 

RCP reinforced concrete pipe 

SBIR Small Business Innovation and Research 

SCG slow crack growth 

SDWA Safe Drinking Water Act 

SRF State Revolving Fund 

SSO sanitary sewer overflow 

STAR Science to Achieve Results 

TIP tight-in-place 

TO Task Order 

TTC Trenchless Technology Center 

UV ultraviolet 

VCP vitrified clay pipe 

WEF Water Environment Federation 

WERF Water Environment Research Foundation 

A-3
 
APPENDIX B 

Wastewater Pipe Rehabilitation Technology Descriptions
 
Sliplining is a method of pipe rehabilitation in which a new pipe of smaller diameter is inserted directly 

into the deteriorated pipe by pulling or pushing. With this method, an annular space between the host pipe 

and the liner is created, which is generally grouted with a cementitious material. The method can be 

categorized into: 

	 Segmental sliplining – A liner is assembled from short pipe segments at the entry point into the 

existing pipe, from where the liner is pulled or pushed into the pipe segment by segment. 

Sliplining pipes are typically manufactured from PE, HDPE, PP, PVC, GRP, or CCFRPM. 

	 Continuous sliplining - A liner is manufactured as a continuous pipe or assembled in the field 

prior to insertion (e.g., by fusing HDPE pipes) to match the entire length of the existing pipe. 

Sliplining pipes typically are PE, HDPE, PP, PVC, or PE/EPDM. 

Example technology: Akkerman SLS 50/100 Sliplining, Vylon® PVC Slipliner Pipe, 

Hobas® SewerLine®, etc. 

Spiral winding is a method of pipe rehabilitation in which a liner is fabricated in the field from a 

continuous plastic strip. The joint between strips is mechanical (the strip has male and female edges 

which self-interlock). The strips, made of PVC (with or without steel reinforcement) or HDPE, have 

external ribs to increase the stiffness of the liner section. These liners may be installed without grouting or 

they may be grouted in place – in which case the external ribs serve to anchor the liner into the cement 

grout. 

Example technology: Rib Loc® Expanda, Sekisui SPR, etc. 

Cured-in-place (CIP) lining is a method in which a resin-saturated tube is inserted into the pipe by 

inversion or winching, then expanded using air or water pressure, and then the resin is subsequently cured 

at ambient or elevated temperature (using steam or hot water), or using ultra violet light, to create a pipe 

within the pipe. The method creates a minimal annular space and no grouting is performed. 

Conventional CIP – A tube is made of a needled felt or equivalent material (in most systems) or a 

fiberglass reinforced material (e.g., AdvantexTM). The resin is usually unsaturated polyester, epoxy vinyl 

ester, or epoxy with catalysts. Based on the liner shape (which is determined by the part of sewer system 

to be relined), the following are different types of conventional CIP liners: 

Standard CIP – The liner is shaped as a simple tube. These liners are used in sewer mainlines and 

laterals. 

Example technology in mainlines: Insituform® CIPP, Inliner® , National Liner, 

Blue-TekTM etc 

Example technology in laterals: PermaLinerTM, MaxLinerTM, Inflex LinerTM, etc. 

Top Hat Liners – For relining a lateral-to-mainline connection, the liner is shaped in the form of a 

top hat. It creates a small brim (approx. 3 inches) in the mainline around the opening and extends 

for a short distance (approx. 6 to 12 inches) into the lateral. 

Example technology: Top Hat® 

T-Liners – For relining both a lateral-to-mainline connection and a lateral, the liner is made from 

two parts: a short mainline CIP (approx. 16 inches) and a standard lateral CIP (up to 160 feet). 

Example technology: LMK T-Liner® 

	 Composite CIP – A tube is a composite made of a conventional CIP material sandwiched 

between layers reinforced with carbon fiber (high stiffness) and/or glass fiber (corrosion 

resistance), with a protective coating (PP) on the inside of installed of installed liner (increased 

surface smoothness and additional corrosion protection). The system is used for medium to large 

diameter pipes. 

B-2
 
Example technology: Insituform’s iPlus® Composite CIPP 

Close-fit lining is a method of pipe rehabilitation in which a liner pipe is temporarily deformed before its 

insertion into an existing (host) pipe and subsequently restored to its original diameter forming a close fit 

with the original pipe. This method is also referred to as modified slip lining. The method can be 

categorized as follows: 

	 Fold-and-form: A PVC pipe is deflected during the manufacturing process into a flat shape (SDR 

26-32) or an H shape (SDR 55-60) and expanded after insertion using pressurization (steam to 

relax and recover the round shape, followed by air pressure to press the liner against the host 

pipe). 

Example technology: Ultraliner PVC Alloy, EX Method®, AM-Liner II®. 

	 Deform-reform: A PE pipe is deflected during the manufacturing process, or on site, into a Cshape (flexible PE pipe) or a U shape (semi-rigid PE pipe, and is held in this shape by a sleeve or 

plastic bands). By this process, the diameter is reduced by approximately 35 to 40 percent for 

easy insertion. The pipe is expanded in place after insertion by the application of pressurized 

steam or water. The PP bands burst open during this process. 

Example technology: U-Liner, Subline, Polyflex. 

	 Symmetrical reduction: The liner is an HDPE pipe, which is temporarily reduced in diameter just 

prior to insertion for easy insertion and is reverted to its original diameter after the insertion 

(either naturally due to the material’s viscoelastic recovery properties or by applying pressure to 

assist the process). The following methods have been developed: 

Tension-based symmetrical reduction (TBSR) – The pipe (SDR 17) is pulled through a 

swage die to reduce its diameter (typically by 7 to 15 percent of OD). With the pipe under 

tension, there is some change in pipe length. After the pull in is completed, the winch is 

disconnected relieving the tension and allowing the liner to viscoelastically recover towards 

its original diameter and hence form a tight fit within the host pipe. 

Example technology: SwageliningTM 

Compression-based symmetrical reduction (CBSR) – The pipe (SDR 11) is hydraulically 

pushed through a series of compression rollers to reduce its diameter (typically by up to 10 

percent of OD). With the pipe under compression rather than tension, there is little change in 

pipe length; however, there is a corresponding increase in the pipe wall thickness. The pipe 

diameter does not immediately try to recover its original shape and the diameter recovery is 

initiated with cold-water pressurization. 

Example technology: Subterra, Rolldown, Polyflex 

Tight-in-pipe (TIP) – Static pipe bursting equipment, lightweight and easily transported, 

is used where space is limited to slipline a failing pipe with a new pipe, which is temporarily 

reduced in diameter for easy insertion (a special tensioning device is used to put a liner pipe 

into tension). Short-module pipes (PVC in U.S., PP in Europe) assembled into a continuous 

pipe on site or a fusion-welded HDPE pipe can be used. The bursting unit has a specially 

designed guiding sleeve with rollers, which pulled through the pipe restores the pipe’s 

circular profile as necessary and the new pipe attached to it is simultaneously pulled in. 

Example technology: TT Technologies’ TIP system using Grundoburst 400s/Burstfix 

tensioning system. 

Grout-in-place (GIP) is a method in which a liner (an HDPE pipe or panels from PP, PVDF, or ECTFE) 

has anchors (V-shaped studs) on the outside of the liner that serve as a spacer to the inner surface of the 

pipe, and the annular space created is filled with a high-strength, cementitious grout. 

B-3
 
 

Example technology: Trolining®, Sure Grip®, etc. 

GRP segmental lining is a method of large pipe rehabilitation (man-entry) in which interlocking glass 

fiber reinforced plastic (GRP) pipe segments are assembled inside the host pipes. The segments are 

manufactured from corrosion resistant isophthalic resin and can be designed for almost any pipe profile 

(circular, oval, vertically sided, symmetrical or non-symmetrical) as one piece, two piece, or multi-piece 

systems. 

Example technology: Channeline Sewer Systems. 

Gunite/Shotcrete is a concrete lining (mixture of sand, aggregate, water, and cement) that is applied by 

spraying layers to the required thickness. Gunite has only fine aggregate while shotcrete contains largersized aggregate. Reinforcing can be provided by spraying the concrete onto a cage of reinforced steel 

positioned and anchored into the sewer wall or by including reinforcing fibers in the shotcrete mix. It is 

normally applied through hand spraying, but robotic shotcrete lining technologies have been developed 

for non-person-entry pipes. 

Example technology: Shotcrete Technologies, Inc. 

Sprayed polymer lining is a method of pipe rehabilitation in which a layer of coating material is sprayed 

onto the surface of damaged pipe in sufficient thickness to create a high-built (HB), semi-structural liner. 

The method can be categorized as follows: 

	 Epoxy lining – An epoxy layer is centrifugally cast onto the pipe surface through a spray head, 

which is attached to a plural-component hose and winched through the host pipe. The thickness of 

application ranges from 40 to 400 mils (1 to 10 mm). 

Example technology: 3M Scotchkote 162PX, Scotchkote 134, 206, or 6233 

	 Polyurethane lining – A polyurethane (fast cure, 100 percent solids) is applied centrifugally onto 

the pipe surface in a thickness typically between 120 and 200 mils (3 and 5 mm). An air-driven 

spray head (the spinner head) is passed through the pipe to create the lining. 

Example technology: Copon Hycote 169 HB, 3M Skotchkote 169 HB (currently 

aimed at the water market). 

	 Polyurea lining – A polyurea (a plural component, fast cure, 100 percent solids elastomeric 

systems) is applied onto the pipe surface using a robotic application system or by conventional 

hand applied procedures in multiple thin layers to build a pipe inside a pipeline with wall 

thickness between 20 and 500 mils (0.5 and 12.5 mm) or greater. 

Example technology: PolySpray Structural Liner. 

Flood grouting is a method in which an isolated section of sewer is consecutively flooded (completely 

filled) with two chemicals, which exfiltrate into the soil through pipe and joints defects, and chemically 

react with each other creating a water-tight seal. The method seals manholes, mainlines, and laterals 

simultaneously in one setup. 

Example technology: Sanipor®. 

Spot repairs involve a variety of methods that typically or exclusively repair relatively short sections of 

pipe, defective joints or defective lateral connections: 

	 Chemical grouting – A chemical grout is injected under pressure through cracks and defective 

joints into the surrounding soil to seal the defective pipe and protect against infiltration/inflow. In 

small diameter pipes (up to 24 inches), the method is applied with packers as a test-and-seal 

procedure. Although basically a spot repair, the method can be used to seal the entire pipe by 

repeating the test-and-seal procedure along the pipe. 

Example technology: Logiball Test-and-Seal Packer. 

B-4
 
	 Robotic repairs – Robots are used for mechanical work (e.g., cutting off or grinding protruding 

laterals, grinding of damaged pipe to expose the virgin pipe material) and for applying a repair 

material (resin or mortar) without or with pressure to the prepared surface, which cures into a 

material compatible with the host pipe and becomes an integral part of the pipe. If pressure is 

applied, the material penetrates the soil behind the defective pipe where a sealing collar is created 

around the pipe. Robotic repairs are carried out as spot repairs anywhere in mainlines or at lateral 

connections. 

Example technology: KA-Te and Jansen Lateral Rehabilitation. 

	 Spot repair sleeves – Prefabricated stainless steel or PVC sleeves are positioned inside the pipe 

while folded and then jacked (snapped) into an expanded shape. The sleeves offer a structural 

repair of damaged pipe but can also restore missing pipe sections without excavation or provide 

infiltration sealing of joints. Although multiple sleeves can be used adjacently, this method is 

typically used to repair relatively short sections of pipes. 

Example technologies are Link-Pipe Grouting SleeveTM and Insta-LinerTM (made up 

from short links of stainless steel sleeves) 

	 Internal joint sealing - A flexible rubber seal is positioned over a leaking joint and compressed 

against the inside diameter of the pipe on both sides of the joint with expansion bands. 

Example technology: Amex10®/Weko-Seal® and NPC Internal Joint Seal. 

Trenchless pipe replacement is a method of replacement of a deteriorated pipe with a new pipe of the 

same or slightly larger diameter along the existing pipe alignment. This may also be referred to as “online” replacement, but this term can be confused with work done “on line” – meaning “in service.” The 

bursting tool (bursting head) is passed through the pipe breaking it into fragments if the pipe is brittle 

(pipe bursting) or slicing through it if the pipe is ductile (pipe splitting), and the new pipe is 

simultaneously pulled in place. The old pipe, whether fractured or sliced open, remains in the ground. The 

new pipe is usually an HDPE pipe, but segmented pipe can be used with modified pipe insertion 

arrangements. The method can be categorized as follows: 

	 Static bursting – The bursting head is hydraulically pulled or pushed through the existing pipe. 

Example technology: TT Technologies Grundoburst®, Hammerhead HydroBurst®, 

etc. 

	 Pneumatic bursting – The bursting head applies repeated impacts onto the existing pipe driven 

by compressed air (delivered through air supply hoses inside the replacement pipe). 

Example technology: TT Technologies Grundocrack® 

	 Hydraulic bursting – The bursting head is hydraulically expanded breaking the pipe, contracted, 

and slid forward to repeat the process incrementally along the existing pipe. 

Example technology: XPANDIT system. 

	 Pipe insertion by pushing – The hydraulic jacks are used to push a new pipe in place of the 

existing deteriorated pipe. The lead equipment (a bursting head) positioned ahead of the new pipe 

penetrates, fractures, and expands the old pipe. The system utilizes the column strength of 

segmented jacking pipe for the newly installed line and only rigid pipe materials can be used 

(clay, ductile iron, polycrete, Hobas, steel and stainless steel). 

Example technology: Tenbusch Insertion Method (TIM)TM. 

Trenchless pipe removal is a method of on-line pipe replacement in which the existing pipe is removed 

from the ground as the new pipe is being pulled in place. The method can be categorized as follows: 

B-5
 
	 Pipe reaming – HDD equipment is used (standard equipment plus a modified back reaming tool). 

During back reaming, the existing pipe is fragmented using pick cutters and the fragments are 

carried out by the drilling fluid along with other excess particles. 

Example technology: Nowak’s InneReam System®. 

B-6
 
APPENDIX C 

Water Pipe Rehabilitation Technology Descriptions
 
Sliplining is a method of pipe rehabilitation in which a new pipe of smaller diameter is inserted directly 

into the deteriorated pipe by pulling or pushing. The method can be categorized into: 

	 Segmental sliplining – A liner is being assembled from short pipe segments at the entry point 

into the existing pipe, from where the liner is pulled or pushed into the pipe for the length of each 

added segment. The annular space is grouted. Sliplining pipes can be HDPE, PVC, CC-GRP 

pressure pipe (Hobas), and ductile iron. 

Example technology: Certa-LokTM YelomineTM, Hobas® WaterLine®, etc. 

	 Continuous sliplining - A liner is manufactured as a continuous pipe or is assembled in the field 

prior to insertion to match the entire length of the existing pipe. Sliplining pipe can be HDPE or 

fusible PVC pressure pipe. One system has been developed that uses a PVC pipe with smaller 

diameter than the host pipe for easy pull in and subsequently applies heat and pressure to expand 

the PVC pipe tightly against the interior walls of the host pipe thus eliminating the annular space. 

Example technology: DuralinerTM. 

Cured-in-place (CIP) lining is a method in which a resin-saturated tube is inserted into the pipe by 

inversion or winching, then expanded using air or water pressure, and the resin subsequently cured at 

ambient or elevated temperature (using steam or hot water), or using ultra violet light, to create a pipe 

within the pipe. For water applications, the tube can be PE woven material or glass-fiber reinforced, 

flexible felt, and the resin is epoxy. Service connections can be reinstated internally without excavating 

(e.g., iTAPTM) 

Example technology: Insituform PPL®, RPPTM Aqua Pipe. 

Woven PE/epoxy lining is a method in which seamless woven-fabric PE flexible tubing with PE coating 

is inverted into the pipe (via air pressure) and glued to the interior wall of the pipe with a solvent -free, 

thermosetting, two-component epoxy adhesive. The gluing operation requires that the interior wall of the 

pipe be clean. 

Example technology: Starline®1000 Nordipipe 

Close-fit lining is a method of pipe rehabilitation in which a liner pipe is temporarily deformed before its 

insertion into an existing (host) pipe and is subsequently restored to its original diameter forming a close 

fit with the original pipe. This method is also referred to as modified slip lining. The method can be 

categorized as follows: 

	 Deform-reform: A PE pipe is deflected during the manufacturing process or on site into a C or a 

U shape to reduce the diameter by approximately 35 to 40 percent for easy insertion. The pipe is 

expanded in place after insertion by the application of pressurized steam or water. If PP bands 

were used to hold the shape prior and during the installation, they burst open during this process. 

Two different categories can be distinguished based on the level of structural repair provided: 

Polyester fiber reinforced polyethylene (PRP) – A thin reinforced PE pipe (the polyethylene 

matrix encapsulates and surrounds the polyester reinforcement) is supplied as factory-folded into 

a “C” shape. It is installed by winching into the host pipe and reverted into the circular shape 

applying air and steam pressure. 

Example technology: Thermopipe® 

Polyethylene (PE) – A thin PE pipe is used. 

Example technology: Insituform PolyFoldTM, Subline®. 

	 Symmetrical reduction: The liner is an HDPE pipe, which is temporarily reduced in diameter just 

prior to insertion for easy insertion and is reverted to its original diameter after the insertion 

C-2
 
 

(either naturally due to the material’s viscoelastic recovery properties or by applying pressure to 

assist the process). The following methods have been developed: 

Tension-based symmetrical reduction (TBSR) – The pipe is pulled through a swage die to 

reduce its diameter (typically by 7 to 15 percent of OD). With the pipe under tension, there is 

some change in pipe length. After the pull in is completed, the winch is disconnected 

relieving the tension and allowing the liner to viscoelastically recover towards its original 

diameter and hence form a tight fit within the host pipe. 

Example technology: SwageliningTM, PolyflexTM 

Compression-based symmetrical reduction (CBSR) – The pipe is hydraulically pushed 

through a series of compression rollers to reduce its diameter (typically by 10 to 20 percent of 

OD). With the pipe under compression rather than tension, there is little change in pipe 

length; however, there is a corresponding increase in the pipe wall thickness. The pipe 

diameter does not immediately try to recover its original shape and the diameter recovery is 

initiated with cold-water pressurization. 

Example technology: Subterra Rolldown, Insituform PolyFlexTM. 

Grout-in-place (GIP) is a method in which a liner (an MDPE pipe) has anchors (closely spaced hooked 

tabs) on the outside of the liner (the side facing the pipe wall) that serve as a spacer to the inner surface of 

the pipe, and the annular space created is filled with a cementitious grout. For installation, the liner is 

pulled into the pipe folded, the grout is injected into the space between the liner and the host pipe, and a 

rounding swab is passed through the pipe (applying air pressure) both rounding the liner tube and 

distributing the grout evenly against the interior surface of the host pipe. 

Example technology: MainSaverTM. 

Sprayed lining is a method of pipe rehabilitation in which a thin layer of coating material is sprayed onto 

the surface of damaged pipe. The method can be categorized as follows: 

	 Cement mortar lining – A continuous lining of cement mortar is applied to protect against 

corrosion (thickness 1

/8 to 3/4 inch per pass is attainable). The method can be applied as a 

centrifugal process (the lining unit has a rotating head that disperses the mortar and a series of 

trowels to smooth the surface) or a mandrel process (the mortar is applied by compressed air and 

smoothed by a conical mandrel). In man-entry pipes, an operator riding on a machine through the 

pipe controls the centrifugal unit. 

Example technology: Mk II (Dakota Pipelining Systems). 

	 Epoxy lining – An epoxy lining is centrifugally cast onto the pipe surface through a spray head, 

which is attached to a plural-component hose and winched through the host pipe. The thickness of 

application is between 1.0 and 5.0 mm and typically about 3.0 mm (1

/8 inch). The lining is nonstructural and provides a corrosion protection. 

Example technology: CuraFlo Spincast SystemTM, Hunting Waterline Epoxy. 

	 Polyurethane lining – A polyurethane (fast cure, 100 percent solids) is applied centrifugally onto 

the pipe surface from an air-driven spray head (the spinner head) passed through the pipe. 

Polyurethane can be applied as a non-structural (thickness up to 1.0 mm) or as a structural lining 

(thickness range of 40 to 200 mils, i.e., 1.0 to 5.0 mm). 

Example technology: Copon Hycote 169 PWX, 3M Skotchkote 169 HB (currently 

waiting for NSF approval). 

	 Polyurea lining – A polyurea (a plural component, fast cure, 100 percent solids elastomeric 

systems) is applied onto the pipe surface using a robotic application system or by conventional 

C-3
 
hand applied procedures. Polyurea can be applied as a non-structural or as a structural lining. As a 

structural lining, polyurea is remotely applied in many thin layers using a reciprocating and 

rotating application head to build a wall thickness in the range of 20 to 500 mils (0.5 to 12.5 mm) 

or greater. 

Example technology: PolySpray Structural Liner. 

	 Calcite lining – A supersaturated solution of calcium carbonate is applied onto the pipe wall 

creating a calcite liner. Portions of municipal water main systems can be closed off, lined quickly 

and put back in service. The method was used by WSSC and LWC. 

Spot repairs involve methods that repair relatively short defective sections of pipe: 

	 Spot repair sleeves – Prefabricated stainless steel sleeves are positioned inside the pipe while 

folded and then are jacked (snapped) into an expanded shape. The sleeves offer a structural repair 

of damaged pipe, but can also restore missing pipe sections without excavation or provide 

infiltration sealing of joints. Although multiple sleeves can be used adjacently, this method is 

typically used to repair relatively short sections of pipes. 

Example technology: Link Pipe Hydro-SealTM Sleeve. 

Trenchless pipe replacement is a method of replacement of a deteriorated pipe with a new pipe of the 

same or slightly larger diameter along the existing pipe alignment. This may also be referred to as “online” replacement, but this term can be confused with work done “on line” – meaning “in service.” The 

bursting tool (bursting head) is passed through the pipe breaking it into fragments if the pipe is brittle 

(pipe bursting) or slicing through it if the pipe is ductile (pipe splitting), and the new pipe is 

simultaneously pulled in place. The old pipe, whether fractured or sliced open, remains in the ground. The 

new pipe is usually an HDPE pipe, but segmented pipe can be used with modified pipe insertion 

arrangements. The method can be categorized as follows: 

	 Static bursting – The bursting head is hydraulically pulled or pushed through the existing pipe. 

Example technology: TT Technologies Grundoburst®, Hammerhead HydroBurst®, 

etc. 

	 Pneumatic bursting – The bursting head applies repeated impacts onto the existing pipe driven 

by compressed air (delivered through air supply hoses inside the replacement pipe). 

Example technology: TT Technologies Grundocrack® 

	 Hydraulic bursting – The bursting head is hydraulically expanded breaking the pipe, contracted, 

and slid forward to repeat the process incrementally along the existing pipe. 

Example technology: XPANDIT system. 

	 Pipe insertion by pushing – The hydraulic jacks are used to push a new pipe in place of the 

existing deteriorated pipe. The lead equipment (a bursting head) positioned ahead of the new pipe 

penetrates, fractures, and expands the old pipe. The system utilizes the column strength of 

segmented jacking pipe for the newly installed line and only rigid pipe materials can be used 

(clay, ductile iron, polycrete, Hobas, steel and stainless steel). 

Example technology: Tenbusch Insertion Method (TIM)TM. 

Trenchless pipe removal is a method of on-line pipe replacement in which the existing pipe has been 

removed from the ground as the new pipe is being pulled in place. The method can be categorized as 

follows: 

C-4
 
	 Pipe extraction – A winching system attached to a cable with embedded pulling heads (or a cable 

that is grouted into the pipe to be extracted) pulls the pipe out of the ground. The new pipe is 

pulled into the ground as the old pipe is pulled out. Lead water pipes are typically extracted. 

Example technology: TT Technology’s Grundomat piercing tool equipped with a 

pipe pushing adapter 

C-5
 
APPENDIX D 

Manhole Rehabilitation Technology Descriptions
 
Preformed manhole units are used to “slipline” existing manholes. The chimney and corbel/cone area 

must be removed, and all infiltration in the bench area and around pipes must be stopped prior to the 

installation. The installation can often be done without sewage bypassing or diversion. 

Monolithic units are one-piece monolithic fiberglass units. 

Example technology: Flowtite® Fiberglass Rehabilitation Manhole 

Composite units consist of a cover section (concentric, eccentric or flat) and riser sections 

(typically each 5 feet high to facilitate installation) made of fiberglass reinforced epoxy resins. 

Example technology: Sewer Shield® Manhole Insert 

Poured-in-place concrete creates thick-wall, seamless concrete liners inside manholes that extend from 

the bench to the frame. Segmented, stackable forms (steel or plastic, available in different nominal 

diameters and height increments) are positioned into the manhole and the concrete is carefully poured 

inside the forms (in 3 to 20-foot lifts, depending on the system). After the concrete has sufficiently cured, 

the forms are disassembled and removed. The repair can often be done with active flows. 

Example technologies: Permaform®, Mono-CastTM, Monoform 

Cured-in-place manhole (CIPM) relining is a method in which a manhole liner, prefabricated to fit the 

structure and resin-saturated at the jobsite, is lowered into the manhole interior, a flexible diaphragm is 

inflated, and the resin is heat cured forming a protective liner within the manhole. The resin is typically an 

epoxy, whereas the liner material differs depending on the system: a laminate containing a non-porous 

membrane bonded between the structural layers of fiberglass (Poly-Triplex®), or PVC polyester 

(MultiPlexxTM PVCP). Manhole preparation includes water pressure cleaning and chemical grouting to 

eliminate infiltration/inflow (if applicable). 

Example technologies: Poly-Triplex®, MultiPlexxTM PVCP Liner. 

Grout-in-place manhole liners are constructed from panels (HDPE or PVC) with anchors (V-shaped 

studs) on the outside of the liner, which serve as a spacer to the manhole surface that create the annular 

space filled with a high-strength, cementitious grout. 

Example technologies: Trolining®, Sure Grip®. 

Cementitious coatings are generally used for structural restoration in low-level corrosion environments. 

They are applied by spraying or spincasting from the center of the manhole (Permacast®) in layers 

approx 1⁄4 inch thick to a total thickness of 1⁄2 inch for I&I elimination or 1 to 4 inches for structural repair. 

These coatings can be made with Type I Portland cement (pH 3.0 or higher) or calcium aluminate cement 

(pH 2.0 or higher). Cement mix and aggregate choices (e.g., a blend of 100 percent pure fused aluminate 

clinker with a minimum aluminate content of 46 percent and calcium aluminate cement) can further lower 

the pH where the corrosion can be avoided (pH 1). Manhole preparation includes water pressure cleaning 

and chemical grouting to eliminate infiltration/inflow (if applicable). The full cure is achieved in 28 days, 

but the flow plugging is required only for 24 hours. 

Example technologies: Strong -Seal®, Permacast®, etc. 

Polymer coatings are used primarily for corrosion protection (they can be applied in conjunction with 

cementitious coatings). They are applied by spraying or spincasting, in thickness range of 80 to 500 mils 

(approx. 1

/8 to 1/2 inch). Generally, only 100 percent solids, solvent-free products are used for safety and 

performance. Surface preparation is critical for success. The following are different types: 

	 Epoxy coatings – These coatings have good adhesion property, excellent chemical resistance, and 

are moisture tolerant. Epoxies are also used as primers for ureas and urethanes. Cure time varies, 

and is usually 5 to 6 hours (Raven) or, if the epoxy is preheated, about 2 hours regardless of 

D-2
 
ambient temperature (Warren). They are typically applied in thickness 120 mils, although some 

recommend minimal thickness 250 mils (Warren). 

Example coatings: Raven Lining Systems, Warren Lining Systems etc 

	 Polyurethane/polyurea coatings - These coatings have good-excellent chemical resistance, but 

are moisture sensitive. All infiltration must be stopped and the surface completely dry to ensure 

adhesion to the substrate. For corrosion protection, they are typically applied in two layers: 

polyurethanes to thickness 150 mils (75 mils/layer) and polyurea to thickness 180 mils (90 

mils/layer). Gel times are very short (several seconds to minutes). The flow can be reinstated in 

30 to 60 minutes. 

Example coatings: Sprayroq (polyurethane), PCSI Polyurea Manhole Coating 

	 Modified polymer skin panels - Systematic layering of polymer resins imparts structural strength 

due to “Stress Skin Panel” effect. The lining system consists of a moisture barrier (siliconemodified polyurea), a surfacing coat to fill voids, eroded areas and missing mortar joints 

(polyurethane/polymeric blend foam), and a final corrosion barrier (silicone-modified polyurea). 

The coats are spray-applied and can be installed in any shape or configuration. Fast curing allows 

lining of a typical, 7-foot deep manhole to be completed about one hour. 

Example technology: SpectraShieldTM 

Chemical grouting is a method in which chemical grouts are used to seal leaking, non-structural defects 

in manholes. The method can be categorized as follows: 

	 Acrylamide/acrylate grouts: Gel type chemical grouts are injected with hand-held injection 

equipment through cracks to the soil surrounding the manhole to form a gel curtain around the 

outside of the manhole. Acrylates are alternatives to the acrylamides, which are toxic in the gel 

phase (before polymerization). Acrylates are not as strong as Acrylamides, have a little higher 

viscosity and not as good gel-time control, and are more expensive. 

Example: AV-100 Acrylamide, Geo/chem AC-400 Acrylate 

	 Polyurethane grouts – Liquid type chemical grouts are used to close active leaks or stabilize the 

soil around the manhole. Polyurethane grouts are water activated. Two types can be 

distinguished: which cure forming either an expansive foam (flexible or rigid): 

Hydrophilic grouts will absorb the water they find in the concrete or soil. Based on formulation 

produce either expansive foam or non-expansive gel. The foam is used to seal the leaks from the 

outside in: the resin is injected under pressure through the manhole wall into the water (a hole is 

drilled near the leak) and, as the resin reacts with water, the expanding foam is pulled back into 

the structure creating the seal through the entire manhole wall. The resin that produces gel is used 

when the leak is not strong enough to pull the grout into the structure: both resin and water are 

delivered through a manifold, mixed briefly, and injected directly into the crack. In both cases, a 

tight flexible seal is formed that expands and contracts as pressure or temperature changes cause 

the crack to open or close. 

Example grouts: Prime-Flex 900XLV, 900LVSF, and 970 Hydro Gel SX 

Hydrophobic grouts will repel the water after activation and push it away. They require a catalyst 

to cure and expand, and form rigid foam (if the structure moves, the leaks can reappear). With 

low viscosity, controlled setup time, and high expansion, hydrophobic grouts are best for filling 

voids and stabilizing soil. 

Example grouts: Prime-Flex 910 and 920. 

D-3
 
 

	 Epoxy grouts – 100 percent solids, two-component epoxy systems are used for grouting and 

sealing of cracks. With ultra-low-viscosity, they are designed specifically for pressure injection. 

Epoxies are moisture insensitive and can be applied on damp surfaces, which must however be 

free of standing water. 

Example grout: Denepox 40 Epoxy 

Flood grouting is a method in which an isolated section of sewer is consecutively flooded (completely 

filled) with two chemicals, which exfiltrate into the soil through pipe and joints defects, and chemically 

react with each other creating a water-tight seal. The method seals manholes, mainlines, and laterals 

simultaneously in one setup. 

Example technology: Sanipor®. 

Manhole under cover inserts involve placing an insert under the manhole cover on top of the manhole 

frame. No special tools are required for installation, but the frame rim must be cleaned of any loose rust 

or scale, and any debris with a wire brush. The inserts can be: 

Dish inserts – HDPE or stainless steel inserts are installed to eliminate inflow, debris and dirt 

into the manhole, and reduce odors and manhole cover rattle noise. 

Example technologies: Sewer Guard® Manhole Insert, No Flow In Flow, Cratex 

Inflow Dish, InflowShield® (stainless steel) 

Grade rings – HDPE rings, flat or sloped, are installed to adjust the manhole cover up to the 

exact height of roadway surface. 

Example technology: Ipex LifesaverTM (24 to 34 inches). 

Chimney seals involve measures focused on sealing joints in the manhole frame-chimney area. The 

following types can be distinguished: 

	 Mechanical – Most chimney inserts are flexible rubber sleeves, which are pleated and secured in 

place with stainless steel expansion bands (the bends are placed in the band recesses and 

individually expanded) providing a watertight seal. In addition, inserts in the form of telescopic 

liners are available, which are made of PVC, easily installed without special tools, and can 

accommodate grade adjustment rings. 

Example technology: Cretex Internal Manhole Joint Seal, FlexRib Frame–Chimney 

Seal, Water-LokTM (telescopic PVC liner) 

	 CIP - The CIP liner capable is used to reline the entire chimney with an overlap typically of 5 to 

6 inches onto the cone section. The liner is made from stretchable “one size fits most” coated 

polyester (22 inches in diameter will stretch to as much as 60 inches), vacuum impregnated with a 

100 percent solids silicate resin, and cured under ambient temperature and pressure in about one 

hour. Surface must be very clean to ensure bonding of the liner with the manhole. 

Example technology: LMK CIPMHTM Chimney 

	 Polymer – These coatings are applied with trowel in the chimney area and ambient cured 

Polysufides - A two-component, trowel-grade polysulfide, 100 percent solids, chemical 

resistant and flexible coating. 

Example technology: Perma-Flex Manhole Chimney Seal 

Epoxy - A 100 percent solids, zero VOC resin is applied with trowel at 20 to 500 mills in a 

single pass. 

Example technology: Neopoxy NPR-5301 

D-4
 
 

Grade adjustment ring area seals involve measures focused on sealing cracks in this manhole area. 

 Polymer – A urethane coating is applied with a brush about 3 inches above the bottom of the 

frame to 3 inches below the bottom of the grade adjustment ring. Two different coats leave final 

thickness of the sealant typically 170 to 250 mils. 

Example technology: Flex-Seal Utility Sealant® 

Barrel joints seals involve measures focused on sealing joints or repairing defects in the manhole barrel. 

The following types can be distinguished: 

 Mechanical – Flexible rubber sleeves are used over the barrel joints, fixed firmly with the 

stainless steel expansion bands to provide a watertight seal. 

Example technology: Cretex Internal Manhole Joint Seal 

 Cementitious – Rapid-setting (1 to 20 minutes) cement-based mortars can be used to stop water 

seepage through cracks in concrete. 

Example technology: Thoroc® mortarts 

 Polymer – Urethane coatings are applied with brush to the manhole joints (from 3 inches above 

the joint to 3 inches below the joint) to a dry and clean surface in two different coats, with final 

thickness of the sealant typically 170 to 250 mils. 

Example technology: Flex-Seal Utility Sealant® 

Channel inserts involve measures focused on rehabilitation of inverts. For lining invert flumes in 

manholes, a plastic composite system can be used. Modular components made of fiberglass (the flume 

sections) and PVC (the pipe ends) bolt together with minimal tools. 

Example technology: Reliner® Channel System 

D-5
 
APPENDIX E 

Example Quality Control Standards for Pipe Rehabilitation
 
The installation of CIPP is governed by the ASTM standards F1216, F1743, and F2019. Fold and form 

PVC installations are governed by ASTM F1867 and F1947; and deformed reformed HDPE is governed 

by ASTM F1606. There is currently no ASTM installation standard for pipe bursting; pipe bursting is 

given its installation criteria by the equipment manufacturers. Additionally, NASSCO’s International Pipe 

Bursters’ Association division has published a guideline entitled Guideline Specification for the 

Replacement of Mainline Sewer Pipes by Pipe Bursting. GIPL are installed using ASTM F1698 or F1741, 

depending on whether the PVC material is hand assembled or machine assembled in the pipeline. 

The differences between ASTM F1216, F1743, and F2019 center on the type of installation to be carried 

out. F1216 focuses on the inversion method of installation while F1743 and F2019 provide guide for a 

pulled in place installation. The thermosetting resin systems used for CIPP are hardened by heating the 

fluid used in the installation process (water or air) or by UV light. The key control points of a CIPP’s 

installation are given by these standards but may not be readily obvious to those not involved in the 

details of the day-to-day installation process. The key control points for CIPP are as follows: 

	 Proper Saturation. The resin system must be impregnated into the fabricated tube such that at 

least 95 percent of the void space is taken up by the resin. This is accomplished by placing the 

tube under a vacuum and distributing the resin equally by running the tube through a set of 

calibration rollers. The amount of resin required is given by the tube manufacturer to the 

contractor. The length of tube saturated and the resin quantity used confirm proper saturation. 

	 Proper Catalyzation. Polyester and vinyl ester resin systems use initiators to start the free radical 

polymerization process that leads to the resin hardening. Initiators are added to the resin system 

by mixing just prior to saturation. A gel test is done routinely throughout the saturation process to 

insure that the resin has been properly catalyzed. 

	 Finished Thickness and Fit Control. The tube manufacturer provides the contractor with the 

required heads to be used during the inversion or pull in place installation procedure to insure that 

the saturated tube fully expands to tightly fit the existing pipeline while achieving the proper 

finished wall thickness. By using these parameters, the contractor can properly pre-plan his 

installations to comply with these parameters. 

	 Proper Curing and Cooling. The standard in the industry is to use initiators that commence curing 

at around 140°F. By using thermocouple wires placed in the interface between the CIPP and the 

host pipe, the installation personnel can observe the exothermic reaction commencing in the liner 

and monitor the progress of the curing. The resin manufacturers in conjunction with the CIPP 

system manufacturers have developed an empirical relationship between the readings observed 

and the time required to cure the resin past the observed exotherm. In order to properly anneal 

any residual stresses from the curing process the liner is cooled down at a steady rate consistent 

with its thickness. Both the length of curing and the cool down timing are given to the installer in 

terms relating to the readings indicated by the thermocouples. 

ASTM F1867 and F1947 dictate the proper installation of a fold and form PVC rehabilitation. The key 

installation control points given by it are as follows: 

	 Maximum Pull-in Force. The winching operation is to be monitored by the installation personnel 

continuously during the insertion process. At no point during the installation is the pulling force 

to be allowed to exceed one-half of the allowable tensile strength of the piping being used for the 

rehabilitation (50 percent of the tensile yield strength at 212°F). 

	 Proper Expansion. The time, temperature, and the pressure must be sufficient enough to 

overcome the extrusion memory of the PVC material being used. These parameters have been 

given to the contractor by the system manufacturer. They are stated in terms of the in situ 

parameters encountered. 

E-2
 
 

	 Cool Down. The piping shall be cooled steadily to below 100°F using compressed air and an after 

cooler. The pressure is not to be released prior to the liner being at or below this point. 

GIPL’s are typically used in pipes ranging from 10 inches in diameter to 78 inches in diameter; though 

they are currently beginning to see more use in larger diameter piping. Examples of GIPL’s are the Danby 

System, RibLoc, Sekisui SPR, the 3S Panel system, and Trolining. These systems place a relatively thin 

thermoplastic material that has been extruded with a profile to greatly improve its bending strength. The 

placement is either by machine winding into place; or by hand placement. The resulting annular space 

must be filled with a cementitious grout material to form a composite structure (lining/grout/host pipe). 

The installation of this type of rehabilitation system currently has two ASTM specifications; one for hand 

installation and one for machine installation. They are ASTM F1698 and F1741, respectively. The key 

control points of the installation process are as follows: 

	 Thermoplastic Material Placement. The strips or panel sections are assembled in the host pipeline 

to the design I.D. Depending on the design thickness of the grout layer, shims are employed to 

properly position the assembled liner within the host pipeline. Shimming also serves to providing 

proper alignment and grade of the lining’s placement. These are checked prior to commencing 

grouting. 

	 Grout Placement. Grout placement is absolutely crucial to the quality of the finished installation. 

With the exception of the 3S Panel System, the installer is blinded by the opaque nature of these 

panels or the procedure used for grouting (Trolining fills the lining with water) to confirm 

complete filling is taking place. To that end the installer is advised to make holes in the lining to 

confirm that grout has reached a certain level in the annulus. The 3S Panel System uses a 

translucent color to allow the installer a real time indicator of the grouting operation. 

Pipe bursting gets its installation controls from the piping manufacturer and the bursting equipment 

manufacturer. As mentioned earlier, the IPBA division of NASSCO has published a guideline 

specification that gives the installer guidance regarding pipe bursting: 

	 Pull-in Force. The bursting equipment has a real time reading of the tensile force being applied to 

the plastic piping, etc. during the pulling in operation. The installer has the necessary information 

from the pipe manufacturer as to the maximum tensile force allowed. 

	 Grade is essentially that of the existing pipeline, which is controlled by alignment of the pulling 

cable inside the host pipe. 

E-3