EPA/600/R-09/049 | May 2009 | www.epa.gov/nrmrl

Condition Assessment of 

Wastewater Collection Systems

STATE OF TECHNOLOGY REVIEW REPORT

Office of Research and Development

National Risk Management Research Laboratory - Water Supply and Water Resources Division
United States 

Environmental Protection 

Agency 

Office of Research 

and Development 

Washington, DC 20460 

Final Report 

May 2009 

EPA/600/R-09/049 

White Paper on 

Condition Assessment of 

 Wastewater Collection 

Systems 
White Paper on 

Condition Assessment of Wastewater Collection 

Systems 

by 

Christopher S. Feeney 

The Louis Berger Group, Inc. 

Scott Thayer 

Redzone Robotics, Inc. 

Michael Bonomo 

ADS Environmental Services, LLC 

Kathy Martel, P.E. 

The Cadmus Group 

Contract No. EP-C-05-058 

Task Order No. 59 

Task Order Manager 

Dr. Fu-hsiung (Dennis) F. Lai 

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 
Disclaimer 

The U.S. Environmental Protection Agency, through its Office of Research and Development, funded and 

managed, and collaborated in the research described herein. It 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 
Contents 

Disclaimer ii
 

Contents iii
 

List of Figures v
 

List of Tables v
 

Symbols and Acronyms vi
 

Executive Summary 1
 

1.0 Overview of Task Order 59 1-1
 

1.1 Project Background 1-1
 

1.2 Purpose and Scope 1-1
 

1.3 Definition of Terms 1-2
 

1.4 Critical Gaps in Inspection Technologies and Condition Assessment 1-3
 

1.4.1 Gravity Line Inspection 1-4
 

1.4.2 Pressure Line/Force Main Inspection 1-4
 

1.4.3 Condition Assessment Protocols 1-4
 

1.5 Research Questions 1-4
 

2.0 Condition Assessment 2-6
 

2.1 Program Development 2-7
 

2.2 Asset Inspection 2-8
 

2.2.1 Selection of Assets for Inspection 2-8
 

2.2.2 Prioritization of Assets 2-9
 

2.2.3 Asset Inspection 2-9
 

2.3 Data Management 2-9
 

2.3.1 Condition Assessment/Asset Management Software 2-9
 

2.3.2 General Database Management Software 2-10
 

2.3.3 Spreadsheet Software 2-10
 

2.4 Data Analysis 2-10
 

2.4.1 Hydraulic Capacity/Hydraulic Restrictions 2-10
 

2.4.2 Structural Condition 2-11
 

2.5 Decision Making 2-13
 

3.0 Dynamics of Wastewater Collection System Failure 3-16
 

3.1 Failure Mechanisms 3-16
 

3.1.1 Hydraulic Restrictions 3-16
 

3.1.2 Hydraulic Capacity 3-16
 

3.1.3 Structural Failure 3-17
 

3.2 Pipe Defects 3-18
 

3.3 Correlations between Assessed Conditions and Performance Measures 3-19
 
4.0 Inspection Technologies 4-21
 

4.1 Camera Inspection 4-22
 

4.1.1 Zoom Camera Inspection 4-23
 

4.1.2 Digital Scanning 4-25
 

4.1.3 Camera Deployment 4-27
 

4.2 Acoustic Technologies 4-30
 

4.2.1 Leak Detectors 4-31
 

4.2.2 Acoustic Monitoring Systems 4-33
 

4.2.3 Sonar and Ultrasonic Testing 4-34
 

4.3 Electrical and Electromagnetic Methods 4-35
 

4.3.1 Electrical Leak Location Method 4-36
 

4.3.2 Eddy Current Testing and Remote Field Eddy Current Technology 4-37
 

4.3.3 Magnetic Flux Leakage Detection 4-40
 

4.4 Laser Profiling 4-41
 

4.5 Flow Meters 4-42
 

4.6 Innovative Technologies 4-43
 

4.6.1 Gamma-Gamma Logging 4-43
 

4.6.2 Ground Penetrating Radar 4-44
 

4.6.3 Infrared Thermography 4-44
 

4.6.4 Micro-Deflection 4-45
 

4.6.5 Impact Echo/Spectral Analysis of Surface Waves (SASW) 4-45
 

4.6.6 Ultrasonic Testing Systems 4-45
 

5.0 Technology Forum Summary 5-46
 

5.1 Background 5-46
 

5.2 General Discussion 5-46
 

5.3 Critical Gaps Identified in State of the Science 5-47
 

5.4 Recommended Next Steps 5-48
 

6.0 References 6-50
 

Appendix A A-1
 

Camera Technologies A-2
 

Acoustic Technologies A-5
 

Electrical and Electromagnetic Products A-7
 

Laser Products A-9
 

iv 
List of Figures 

Figure 2-1: Condition Assessment 2-6
 

Figure 5-1: Technology Forum Attendees 5-49
 

List of Tables 

Table ES-1: Summary of Emerging and Innovative Technologies ES-4
 

Table 2-1: Condition Assessment Matrix 2-15
 

Table 3-1: Most Common Pipe Defects Identified 3-19
 

Table 4-1: Inspection Technology Overview 4-21
 

Table 4-2: Zoom Camera Inspection Summary 4-24
 

Table 4-3: Digital Camera Scanning Inspection Summary 4-26
 

Table 4-4: Pushcam Product Comparison 4-28
 

Table 4-5: Lateral Launcher Product Comparison 4-29
 

Table 4-6: Small Diameter Tractor Product Comparison 4-29
 

Table 4-7: Long Range Tractor Product Comparison 4-29
 

Table 4-8: Acoustic Technology Summary 4-31
 

Table 4-9: Sonar Product Comparison 4-35
 

Table 4-10: Electrical and Electromagnetic Methods Summary 4-36
 

Table 4-11: MFL Product Comparison 4-41
 

Table 4-12: Laser Profiling Summary 4-41
 

v 
Symbols and Acronyms 

2D Two dimensional 

3D Three dimensional 

A Access point 

ACI American Concrete Institute 

AET Acoustic emission testing 

AwwaRF American Water Works Association Research Foundation (now Water Research 

Foundation) 

B Broken 

BEM Broadband electromagnetic methodology 

BW Brick work 

C Crack 

CARE-S Computer Aided Rehabilitation Program for Sewers 

CCTV Closed-Circuit Television 

CDMA Code Division Multiple Access 

CMOM Capacity, Management, Operation and Maintenance 

CWA Clean Water Act 

D Deformed or deposits 

DVD Digital video discs 

ECT Eddy current testing 

EDGE Enhanced Data Rates for Global Evolution 

EPA Environmental Protection Agency 

F Fracture 

FELL Focused Electrode Leak Location System 

FL Longitudinal fracture 

FMEA Failure Mode and Effects Analysis 

ft. feet 

GIS Geographic Information System 

gpm gallons per minute 

gpm/in-mile gallons per minute per inch diameter per mile length 

GPR Ground penetrating radar 

GPRS General Packet Radio Service 

GPS Global positioning system 

H Hole 

HDPE high density polyethylene 

HSV Hole with visible soil 

I Infiltration 

I/I Inflow and infiltration 

in. inches 

vi 
IP internet protocol 

IRT Infrared thermography 

IS Intruding seal material 

J Joint 

KPI Key performance indicator 

L Line 

LED Light-emitting diode 

LF Lining failure 

M Miscellaneous 

MACP Manhole Assessment Certification Program 

MCU Camera underwater 

MFL Magnetic flux leakage 

NA Not applicable 

NACWA National Association of Clean Water Agencies 

NASSCO National Association of Sewer Service Companies 

OB Obstacles 

O&M Operations and Maintenance 

ORD Office of Research and Development 

PACP Pipeline Assessment Certification Program 

PCCP Pre-stressed concrete cylinder pipe 

PR Point repair 

psi pounds per square inch 

PTZ Pan-Tilt-Zoom 

PVC Polyvinyl chloride 

R Roots 

RCP Reinforced concrete pipe 

RFEC Remote field eddy current 

RFEC/TC Remote field eddy current/transformer coupling 

S Surface damage 

SASW Spectral Analysis of Surface Waves 

SCADA Supervisory Control and Data Acquisition 

SCRAPS Sewer Cataloging, Retrieval, and Prioritization System 

Sonar Sound navigation and ranging 

SSET Sewer scanning evaluation technology 

SSO Sanitary sewer overflow 

T Tap 

TC Transformer coupling 

U.S. United States of America 

USEPA United States Environmental Protection Agency 

VCP Vitrified clay pipe 

V Vermin 

vii 
VR Vermin including rats 

WEF Water Environment Federation 

WERF Water Environment Research Federation 

WF Weld failure 

WRc Water Research Centre (United Kingdom) 

X Collapse 

viii 
Executive Summary 

In 2007, the United States Environmental Protection Agency (USEPA) finalized a research program 

entitled “Innovation and Research for Water Infrastructure for the 21st Century” that will generate the 

science and engineering knowledge needed to improve and evaluate innovative technologies to reduce the 

cost while improving the effectiveness of operation, maintenance, and replacement of aging and failing 

drinking water and wastewater treatment and conveyance systems (USEPA, 2007). Task Order 59, 

Condition Assessment of Wastewater Collection Systems, is one of several projects being conducted 

under this research initiative. 

Overview 

The objectives of Task Order 59 are to comprehensively review condition assessment technologies and to 

investigate condition assessment approaches for wastewater collection systems. Specific project 

objectives include: 

•	 Identify and characterize the state of condition assessment technology for wastewater 

collection systems. 

•	 Research and evaluate performance and cost of innovative and advanced infrastructure 

monitoring technologies including wireless and remote sensing approaches developed in 

other industries and their applicability to wastewater collection sewers. 

•	 Identify and evaluate innovative closed-circuit television (CCTV) technologies currently used 

by more advanced wastewater utilities for transfer to utilities at large. 

•	 Prepare protocols, metrics, and site selection criteria for field demonstration of selected 

innovative condition assessment technologies and decision-support systems. 

This White Paper is one of the first work products created under Task Order 59 and was used as a basis 

for discussions at the project’s Technology Forum in September 2008. The White Paper summarizes the 

current state of condition assessment technologies, reviews mechanisms of pipe failure, discusses 

emerging and innovative technologies for sewer inspection, and presents a summary of the Technology 

Forum. It incorporates feedback received at the Technology Forum. 

Condition Assessment 

The primary components of any asset management program include the identification, location, and 

condition of assets. Condition assessment provides the critical information needed to assess the physical 

condition and functionality of a wastewater collection system, and to estimate remaining service life and 

asset value. After the field inspection, pipe defects are classified using a standard coding system and pipe 

condition is assessed using a systematic method to produce consistent, useful information. Following 

data analysis, condition assessment information is used to make estimates of a pipe’s remaining useful life 

and its long-term performance, and to make decisions about pipe rehabilitation, pipe replacement and/or 

further inspections. 

Dynamics of Wastewater System Failure 

In conducting condition assessment, it is important to understand the dynamics of pipe failure including 

the level, type, and severity of a failure mechanism. Failure can be a sudden, catastrophic collapse of a 

pipe, restricted hydraulic capacity, or a variety of other performance conditions that result in the inability 

of the pipe to perform as necessary for the minimum acceptable level of operation of the system. The 

purpose of condition assessment is to detect pipe defects which indicate the likelihood of pipe failure, as 

well as to assess the collection system’s performance. This section discusses the mechanisms of pipe 

failure, the various types of pipe defects, and the relationship between the condition of a pipe and its 

Page ES-1 
performance. It is important to understand that the mechanisms and impacts of pipe failure are highly 

dependent upon the pipe material and type of sewer (i.e. force main, gravity line). 

Inspection Technologies 

There are a variety of technologies available for assessment of collection systems. These technologies, 

summarized in Table ES-1, include: 

•	 CCTV is a well-established and common industry method used for inspecting pipes. It 

provides visual data on leaks, location of service laterals, and sediment and debris 

accumulation. The primary disadvantages to CCTV technology are that it only provides a 

view of the pipe surface above the waterline; it does not provide any structural data on the 

pipe wall integrity; and it does not provide a view of the soil envelope supporting the pipe. 

For inspections of gravity lines, basic CCTV systems are not able to measure slope. There 

are needs for higher resolution cameras with better lighting; and improvements in crawler 

technology to better negotiate obstructions, grease, and off-set joints. The quality of defect 

identification and pipe condition assessment using CCTV is highly dependent on many 

factors including operator interpretation, picture quality, and flow level. Innovative camera 

technologies include zoom cameras, digital inspection, push cameras, and advances in 

crawler technology. 

•	 Acoustic technologies use measuring devices to detect vibrations and/or sound waves. In 

pipeline assessment, acoustic sensors are used to detect signals emitted by defects. Three 

types of acoustic technologies are used for pipeline assessment: leak detectors, which are 

used to detect the acoustic signals emitted by pipeline leaks; acoustic monitoring systems, 

which are used to evaluate the condition of pre-stressed concrete cylinder pipe (PCCP) by 

detecting the signals emitted by breaking pre-stressed wires; and sonar, or ultrasonic systems, 

which emit high frequency sound waves and measure their reflection in order to detect a 

variety of pipe defects. 

•	 Electrical/Electromagnetic currents are the basis of several sewer evaluation techniques. 

The electrical leak location method is used to detect leaks in surcharged non-ferrous pipes. 

Eddy Current Testing (ECT) and Remote Field Eddy Current (RFEC) technology identify 

defects in ferrous pipes. Magnetic Flux Leakage (MFL) inspection is widely used in the oil 

and gas industry to measure metal loss and detect cracks in ferrous pipelines. 

•	 Laser profiling uses a laser to create a line of light around the pipe wall, highlighting the 

shape of the sewer. This technique allows for the detection of changes to the pipe’s shape, 

which may be caused by deformation, corrosion, or siltation. Laser inspection can only be 

used to inspect the portions of a pipe wall that are above the water line. To assess the entire 

internal surface of a pipeline requires the pipe to be taken out of service. Lasers are often 

used in combination with other inspection methods, most commonly CCTV and/or sonar. 

•	 Innovative methods based on a variety of technologies are currently being developed for the 

evaluation of sewer collection systems. Gamma-gamma logging is a technique used 

primarily to evaluate cast-in-place concrete pilings and can provide information on the 

average bulk density of the concrete and the location of voids. Ground Penetrating Radar can 

detect underground voids, and is potentially useful for examination of pipe bedding and to 

locate leaks. Infrared Thermography involves the use of an infrared camera to measure the 

temperature differential across an object and is a potential method of detecting sewer defects 

such as leaks and voids. Micro-Deflection is a nondestructive technology used to evaluate 

general conditions and joint integrity of brick, concrete, and clay structures using a load to 

create a slight deformation or micro-deflection in the test material. Impact Echo and Spectral 

Analysis of Surface Waves (SASW) are acoustic wave techniques for locating and measuring 

cracks, delaminations, voids, and honeycombing in concrete and masonry. 

Page ES-2 
Summary of Technology Forum 

A technology forum was held on September 11 and 12, 2008 in Edison, New Jersey to discuss the state of 

the science for condition assessment of wastewater collection systems and to identify critical gaps in 

current knowledge. A draft of the White Paper was distributed to participants in advance of the meeting 

and served as a basis for forum discussions. The objective of the forum was to present the findings of the 

research and obtain direction for additional research and further evaluation during the field demonstration 

tasks. The forum included discussions on data needs for conducting condition assessment and making 

asset management decisions; use of flow monitoring for asset management; systematic approaches to 

condition assessment; the importance of understanding the mechanisms of pipe failure; and tools and 

models available for conducting risk-based decision making related to wastewater assets. 

Critical gaps in our knowledge of inspection technologies, and our ability to diagnose and predict 

infrastructure failures were identified at the Technology Forum and summarized below. 

1.	 Research is needed to further define the costs and benefits of pipe inspection and 

rehabilitation as part of a utility’s condition assessment program. Methods of determining the 

impact of deteriorating collection systems on municipal budgets are needed. 

2.	 Inspection technologies need to be identified for the following applications: 

a.	 Reduce use of confined space entry during sewer system inspections and investigations. 

b.	 Affordable inspection technology that utilizes multi-sensor devices on a small 

transportable package. 

c.	 Inspecting pipes below the waterline. 

d.	 Inspecting force mains that are in service. 

e.	 Inspecting laterals. 

3.	 Data management methods and models are available, but a lack of data standardization makes 

it difficult to compare historical data collected with different inspection technologies that 

have proprietary data structures. 

4.	 Research is needed to improve how asset condition is tracked over time. Geospatial 

information (with a high degree of accuracy) needs to be collected along with pipe condition 

data in order to link historical inspection data with an exact physical location. 

Information transfer to practitioners was identified as a critical industry need. Practitioners need training 

on topics such as infrastructure failure mechanisms; using historical inspection data for condition 

assessment applications; applying the Pipeline Assessment Certification Program (PACP) coding system 

to characterize pipe defects; developing a condition assessment program; and preparing accurate record 

drawings for new and rehabilitated pipe. In addition, practitioners need simple condition assessment tools 

(i.e. scattergraphs for analyzing flow data, decision trees, rules of thumb). 

Page ES-3 
Table ES-1: Summary of Emerging and Innovative Technologies 

Technology 

CCTV Acoustic Electrical & Electro-magnetic Lase r 

Conventional

Zoom camera 

Digital scanning

Push-camera inspection 

In-line leak detectors 

Acoustic monitoring 

systems 

Sonar/ultrasonic 

Electrical leak location 

Remote field eddy current

Magnetic flux leakage

Laser profiling 

Gamma-gamma logging 

Application Pipe type G G G S G, F F G, F G, F, S G,F,S G,F,S G, F G,F,S 

Pipe material Any Any Any Any Any PCCP Any NF F F, PCCP Any C 

Pipe size >6” >6” 6”-60” 1”­ 12” >4” >18” >2” >3” >2” 2”-56” > 4” Not yet defined 

Defects Detected Sediment, debris, roots ● ● ● ● ● ●

Pipe sags & deflections ● ● Partial ● ● ●External pits & voids ● ● Corrosion & metal loss Partial ● ● ● ●Off-set joints ● ● Partial ●Pipe cracks ● ● ● ● ● ● ● ● Leaks ● ● ● ● ● ● ● Broken pre-stressed wires ● ●Wall thickness ● Service connections ● ● ● ●Bedding condition ● Bedding voids ● 

Deteriorated insulation 

Overall condition 

Pipe type: G – Gravity line F – Force main S – Service lateral 

Pipe material: NF – Nonferrous F – Ferrous B – Brick C – Concrete PCCP – Pre-stressed concrete cylinder pipe 

Page ES-4 
1.0 Overview of Task Order 59 

In 2007, USEPA finalized a research program entitled “Innovation and Research for Water Infrastructure 

for the 21st Century” that is being implemented by the Office of Research and Development. It will 

generate the science and engineering knowledge needed to improve and evaluate innovative technologies 

to reduce the cost while improving the effectiveness of operation, maintenance, and replacement of aging 

and failing drinking water and wastewater treatment and conveyance systems (USEPA, 2007). Task 

Order 59, Condition Assessment of Wastewater Collection Systems, is one of several projects being 

conducted under this research initiative. 

1.1 Project Background 

In 2002, the USEPA Office of Water published a report entitled “Clean Water and Drinking Water 

Infrastructure Gap Analysis” (USEPA, 2002). The Gap Analysis report identified a critical shortfall in 

funding of the nation’s water and wastewater infrastructure including a $270 billion gap for wastewater 

infrastructure for the years 2000-2019. The deferred maintenance approach to operating and maintaining 

the nation’s aging wastewater infrastructure has become a paramount concern of the Agency. 

Failing wastewater infrastructure can pose a significant threat to public health and the environment. 

Wastewater infrastructure may include sanitary and combined sewer components, but this project is 

focused only on sanitary sewer systems. Systems with inadequate hydraulic capacity and/or blockages 

may lead to sanitary sewer overflows (SSOs) and may cause flooding damage to private property or 

release untreated sewage to receiving waters. Some of the health hazards associated with basement 

flooding by untreated wastewater include the potential presence of pathogenic microorganisms such as 

viruses, bacteria, and protozoa. 

USEPA and State regulators have taken legal action against utility districts for property damage and 

SSOs. For example, in 2005, a settlement of $300 million was reached with the Washington Suburban 

Sanitary Commission to implement a program to reduce occurrences of basement flooding. This joint 

settlement was reached among the utility district, USEPA, State of Maryland, and five local citizens 

groups. In 2004, Knoxville Utility Board reached a settlement with the State of Tennessee for a capital 

improvements program of $350 million to eliminate flooding due to hydraulic restrictions. In 2004, 

Hamilton, Ohio reached a settlement to implement a program to eliminate SSOs and basement flooding 

that was estimated to cost approximately $1.5 billion. 

1.2 Purpose and Scope 

The objectives of Task Order 59 are to comprehensively review condition assessment technologies and to 

investigate condition assessment approaches for wastewater collection systems. The primary goal of the 

project is to develop more efficient and cost-effective means to conduct condition assessment and to use 

the information as part of a risk-based asset management approach to planning. Specific project 

objectives include: 

•	 Identify and characterize the state of condition assessment technology for wastewater 

collection systems. 

•	 Research and evaluate performance and cost of innovative and advanced infrastructure 

monitoring technologies including wireless and remote sensing approaches developed in 

other industries and their applicability to wastewater collection sewers. 

•	 Identify and evaluate innovative CCTV technologies currently used by more advanced 

wastewater utilities for transfer to utilities at large. 

Page 1-1 
•	 Prepare protocols, metrics, and site selection criteria for field demonstration of selected 

innovative condition assessment technologies and decision-support systems. 

To meet these project objectives, a stakeholder group was established to review all task products, and a 

technology forum was convened to help compile and assess the current state-of-the-art and evolving 

technologies including any critical gaps in performance, affordability or applicability to wastewater 

collection systems. During the literature review for the White Paper, internal camera inspection 

technologies were researched and evaluated for immediate transfer to utilities at large; advanced integrity 

assessment technologies that apply non-contact, remote sensing approaches were also reviewed. In the 

main portion of the project, protocols/metrics for field demonstration of selected technologies will be 

developed, as will criteria for selecting demonstration sites. Finally, field demonstrations of select 

technologies will be conducted. 

The work products resulting from the project will include: 

•	 White paper summarizing current state of the technology. 

•	 Summary of technology forum discussions and findings. 

•	 Comprehensive inventory of condition assessment technologies. 

•	 Information transfer document on internal camera inspection technologies. 

•	 Information transfer document on advanced integrity monitoring technologies. 

•	 Quality assurance project plan for conducting field demonstrations and data analysis. 

•	 Technical memoranda summarizing each task. 

•	 Final project report. 

A draft white paper was prepared and used as a basis for discussion at the project’s Technology Forum 

held in Edison, NJ on September 11 and 12, 2008. It was distributed to the expert panel, stakeholders and 

other participants in advance of the meeting. This final white paper incorporates feedback received at the 

Technology Forum. 

1.3 Definition of Terms 

A wastewater collection system or sanitary sewer system is defined as the network of pipes and pumping 

systems used to convey sanitary flow to a wastewater treatment facility for treatment prior to discharge to 

the environment. A wastewater collection system is designed to convey only sanitary flow, whereas a 

combined system is designed to convey sanitary and stormwater flows. 

A gravity line is a sewer pipe that is sloped to convey flow via gravitational forces. Typical design 

standards are based on open channel flow equations under normal flow conditions utilizing Manning’s 

equation. Design criteria for a gravity line generally take into consideration anticipated defects as a pipe 

remains in service. An allowable rate of inflow and infiltration expressed in terms of gallons per minute 

per in. diameter per mile length (gpm/in-mile) is included in hydraulic design of gravity lines. It is also 

typical to select a frictional coefficient that is based upon a sediment accumulation at the invert of the 

pipe. The minimum diameter of a gravity line (excluding service laterals) is typically 8 inches (in.); 

however, large interceptors can have diameters in excess of 12 feet (ft). Older systems may contain 6-in. 

gravity lines. 

Service laterals are the gravity lines that convey wastewater from a building’s foundation to the sanitary 

line, or main, in the street. The ownership of the service lateral varies widely from area to area. It may be 

defined by property line limits, with the private sewer lateral extending from the house or building 

foundation to the property line and the municipal or public lateral located within the public right of way. 

In other cases, the property owner may own the service lateral all the way to the main. 

Page 1-2 
A force main is a pressure line used to convey pumped sewage. The Water Environment Research 

Federation (WERF) 2004 survey indicated that force mains comprise, on average, 7.5% of a collection 

system. This percentage does vary considerably depending on the region and the topography. 

Approximately 46% of the force mains have diameters less than 12-in. and 20% are greater than 36-in. 

The most common pipe materials for force mains are cast iron and ductile iron. 

Asset Management - The primary components of any asset management program include the 

identification, location, and condition of assets; the determination of their useful life and their valuation. 

The key to asset management is to understand the types, frequency, and costs of failure. Asset 

management often employs a risk-based management approach that utilizes information on asset failures 

as part of a decision making model to manage funding and maintenance priorities. One risk model often 

employed is Failure Mode and Effects Analysis (FMEA). FMEA analyzes a system’s potential failure 

modes so they can be classified by severity or determination of the effect upon the system. It is widely 

used in manufacturing as a risk mitigation tool in various phases of product life cycle and product quality 

planning. 

The Water Research Foundation (formerly the American Water Works Association Research Foundation 

(AwwaRF)) and the Water Environment Federation (WEF) have both produced guidance documents on 

asset management and risk-based analysis of assets. The Capacity, Management, Operation and 

Maintenance (CMOM) program also outlines the framework necessary to develop an information-based 

strategy on managing assets. Such approaches are not unique to the wastewater industry. Developing an 

understanding of the risks and potential costs of system failure can aid in the decision making process. 

Condition assessment is one of the core components of an asset management program. It provides the 

critical information needed to assess the condition and remaining useful life and long-term performance 

of a piping system. Condition assessment can also be used to determine the functionality of the pipes in 

meeting their design criteria. USEPA has defined “condition assessment” as the collection of data and 

information through the direct inspection, observation, and investigation and in-direct monitoring and 

reporting, and the analysis of the data and information to make a determination of the structural, 

operational and performance status of capital infrastructure assets (USEPA, 2007). 

The type of pipe defect varies depending on the pipe material and pipe diameter, as discussed in Section 

3.2. The most prevalent defects are as follows: cracks/broken pipe, root intrusion, sediment, grease 

build-up, off-set joints, corrosion, manhole frame and cover leaks, and pipe sags. 

Pipe failure includes collapse, which may cause extensive property damage and/or discharge of untreated 

sewage, severe hydraulic restrictions, and severe decrease in hydraulic capacity. Other less severe pipe 

conditions could also be considered “failure” depending on the performance standards set for the system. 

The term inspection technologies in this white paper refers to the various methods used for detecting pipe 

defects, structural and operational condition, and environmental conditions that could potentially impact 

pipe condition. These technologies, discussed in Section 4.0, have varying abilities for detecting and 

quantifying specific types of pipe defects. Inspection technologies may have limited applications 

depending on pipe material and/or pipe diameter. A robust condition assessment method would likely 

include a variety of inspection technologies, based on the specific characteristics of a utility’s sewer 

network. 

1.4 Critical Gaps in Inspection Technologies and Condition Assessment 

A previous research project (Thomson et al., 2004) surveyed large wastewater utility districts to 

determine critical gaps in condition assessment of gravity pipelines and force mains. The survey found 

that 100% of the 31 survey respondents relied almost exclusively on CCTV as the primary means to 

inspect pipes. The general limitations of current CCTV technology were the focus of the identification of 

critical gaps. There were also several respondents who expressed concerns with the inability to measure 

Page 1-3 
the structural integrity of the pipe wall and the inability to measure crown corrosion of concrete pipe and 

internal corrosion for ferrous pipes. 

1.4.1 Gravity Line Inspection 

The majority of sewer pipeline inspection activities performed by utilities involve gravity pipelines. In 

the 2004 utility survey (Thomson et al. 2004), critical gaps for inspection technologies for gravity lines 

were defined as follows: 

•	 The needs for improvements to CCTV - higher resolution cameras with better lighting; 

improvements in crawler technology to negotiate obstructions, grease, offset-joints; and 

cameras for inspection of laterals. 

•	 Ability to monitor in surcharged (i.e., flooded) conditions. 

•	 Inability to obtain information on pipe wall thickness. 

•	 Inability to measure slope. 

•	 Inability to locate manholes1. 

•	 Inability to locate soil voids above or below a pipe segment. 

•	 Inability to quantify corrosion (e.g., internal, external). 

1.4.2 Pressure Line/Force Main Inspection 

Inspection of force mains is currently limited to pipelines that are taken out of service. For this reason, 

force mains are infrequently inspected by utilities, primarily because of the inability to take the line out of 

service without costly by-pass pumping. Other critical gaps in inspection of force mains include the 

limited number of inspection technologies suitable for use in force mains; and the inability to determine 

wall thickness, cracking, and pitting with currently available inspection technologies (Thomson et al. 

2004). 

1.4.3 Condition Assessment Protocols 

Based on a survey of twenty-four Canadian sewer agencies using condition assessment protocols, 

Rahman and Vanier (2004) identified the lack of consistent, standard condition assessment protocols as a 

critical gap. The survey results showed 68% of the respondents used a protocol based on that of the 

National Water Research Council. The biggest gaps identified were systematic collection of data and use 

of formal risk assessment methods to prioritize resources for maintenance and rehabilitation activities. 

Research has focused on the use of models to standardize the risk-based decision-making process. 

1.5 Research Questions 

The following key research questions relating to sewer inspection and condition assessment have emerged 

from EPA research (USEPA, 2007). These questions reflect critical gaps in our knowledge of the 

performance of innovative inspection technologies, our understanding of proven condition assessment 

techniques, and our ability to diagnose and predict infrastructure failures. 

•	 Can emerging and innovative inspection technologies be identified and demonstrated in field 

settings to improve our understanding of their cost-effectiveness, technical performance, and 

reliability? 

1

 Other sources indicate that manholes can be located via CCTV inspection. CCTV crawlers can be equipped with 

radio transponders to aid in manhole location. 

Page 1-4 
•	 Can advances in remote monitoring and wireless technologies be applied to reduce confinedspace entry requirements for sewer system inspection and investigation? 

•	 What measurements or operational data can be used to determine and track the condition of 

assets over time? 

•	 Can standard technical guidelines, uniform data requirements, and indicators be developed 

for condition assessment of sewers and non-sewer assets, including manholes, service 

laterals, and pipe joints? 

•	 Can technical guidance be developed for establishing an overall wastewater infrastructure 

inspection program, including inspection prioritization, inspection frequency, inspection type 

(physical vs. visual, maintenance vs. structural), inspection by asset type, and inspection costeffectiveness? 

•	 How can a municipality determine the impact of deteriorating collection systems on their 

financial budgets? 

•	 Can infrastructure failure mechanisms be better characterized to improve risk assessment 

models? 

Page 1-5 
2.0 Condition Assessment 

Condition assessment has gained considerable attention in recent years amongst municipalities and utility 

districts as a component of an asset management program. It can be used to prioritize infrastructure 

projects based on relative risk, thereby easing the financial burden on wastewater utilities and their 

customers. WERF estimates that wastewater utility purveyors spend approximately $4.2 billion annually 

to rehabilitate sanitary pipelines. Local and state governments are required to tabulate the value of their 

public assets (i.e., buildings, roads, utilities, etc.) to support the development of a unified cost accounting 

system, per the Governmental Accounting Standards Board Bulletin 34. This program requires detailed 

financial accounting of all assets, however, the level of detail to which it is implemented can vary from 

city to city. Condition assessment can also assist utilities in implementing USEPA’s proposed guidance 

for evaluating the Capacity, Management, Operation, and Maintenance (CMOM) program for sanitary 

sewer collection systems (USEPA, 2005). The CMOM program requires a municipality that operates a 

sanitary sewer system to provide adequate conveyance capacity for all parts of the system and to take all 

feasible steps to stop and mitigate the impacts of sanitary sewer overflows. 

A variety of processes have been developed for performing condition assessments, ranging from simple to 

complex. They generally follow a similar progression of steps: setting objectives for the condition 

assessment, identification of assets and available data, asset inspection, data analysis, and decision 

making. Specific condition assessment processes are described in the WERF publication “Condition 

Assessment Strategies and Protocols for Water and Wastewater Utilities” (Marlow et al., 2007) and in the 

National Research Council’s “Guidelines for Condition Assessment and Rehabilitation of Large Sewers” 

(McDonald and Zhao, 2001). Figure 2-1 illustrates the steps in the condition assessment process. 

Inventory database 

Impact assessment 

Prioritization 

Frequency of 

next inspection Inspection 

Rehabilitation 

Condition 

Assessment 

Decision- making on 

rehabilitation actions 

Source: McDonald and Zhao, 2001 

Figure 2-1: Condition Assessment 

Page 2-6 
2.1 Program Development 

The development of a condition assessment program must first consider the program drivers and 

objectives. The drivers may include regulatory compliance, operation and maintenance efficiency, risk 

management, and/or financial budgeting forecast. Often, the primary driver for wastewater utilities is 

investigation of sources of infiltration/inflow (I/I) that would require a system-wide condition assessment 

program. Other utilities are more concerned with identifying high risk pipes for which a catastrophic 

failure could lead to extensive service disruptions and environmental damage. A risk-based condition 

assessment program would focus on specific pipes that present these types of risk. 

Objectives for performing the condition assessment should be explicitly stated, so that the program’s 

effectiveness can be evaluated. The objectives will also establish how the results of the condition 

assessment will be used in the decision making process, the final step of condition assessment. Key 

performance indicators (KPIs), metrics used to determine the utility’s progress to defined goals, would be 

defined at this step. Objectives for performing a condition assessment could be to understand the 

structural condition, performance, and/or progression of deterioration (i.e. remaining service life) of the 

asset. 

The costs of conducting condition assessment must be documented and compared to the anticipated 

benefits in order to justify the program. The costs are typically easier to quantify but should include both 

the direct costs of inspection and the indirect costs to the utility and other parties of carrying out the 

inspection work and collecting and analyzing the data. The benefits are more difficult to quantify and 

derive mainly from the reduction in the risk of failure (likelihood times consequences of failure) and from 

the knowledge that allows maintenance, rehabilitation and replacement to be carried out on the most cost 

effective schedule. More specifically, the costs of condition assessment include: 

•	 Equipment and labor costs to conduct field inspections including excavation, traffic control, 

road surface restoration, monitoring equipment and data collection. 

•	 Labor costs before and after field work for planning, data analysis and reporting. 

•	 Cost of service disruptions due to inspection work. 

Specific benefits of a condition assessment program may include: 

•	 Avoided emergency repair costs. 

•	 Avoided costs of extended service disruptions due to a catastrophic failure. 

•	 Avoided restoration costs due to environmental and property damage from a catastrophic 

failure. 

•	 Avoided public health costs (i.e. injury, death, disease transmission) from catastrophic 

failure. 

•	 Improved planning and prioritization of rehabilitation and replacement projects due to 

condition assessment information and improved estimates of service life. 

•	 Avoided costs of premature pipe replacement or rehabilitation. 

Comparing the costs to benefits for gravity sewers and force mains, it has been reported (Thomson 2008) 

that: 

•	 The cost of inspection of gravity sewers is typically low with respect to the value of the asset 

(e.g. the cost of inspection of a 12-in diameter sewer at 13-ft depth is less than 1% of the asset 

value) and the proportion decreases with increasing depth and diameter of sewer. 

•	 The benefits from inspection of gravity sewers are likely to exceed costs for all but small 

diameter sewers at shallow depths. 

Page 2-7 
•	 The cost of inspection of force mains is high with indirect costs often exceeding the direct 

costs of inspection (emptying the line, providing temporary bypass, accessing the line). 

•	 The monetary benefits of inspection may be less than the cost of inspection for smaller lines 

in less populated areas (fail and fix approach may be chosen) although this ratio may change 

in environmentally sensitive areas. The benefits increase greatly for larger diameter force 

mains and urban areas due to the increased risk of major consequences. 

When performing condition assessment, it is essential to compile an inventory of assets and existing 

system data (i.e. pipe material, size, age, maintenance history, inspection records). The utility should 

understand the content and form of existing data, and should identify data gaps at this step. System maps 

and geographic information system (GIS) databases are good information resources. Inspection and 

testing records may include I/I studies: flow data, smoke testing, flow isolation studies, and/or dye tracer 

studies. Failure data from within the system or from research on similar conditions (e.g., soil bedding 

type, material, age) in utility districts can be used to define risk of failure. Data gaps identified in this 

step are used to plan the inspection program. 

A key difficulty in developing a rational inspection, condition assessment, and asset management 

program is that some of the most critical elements of the sewer infrastructure are the most difficult and 

expensive to inspect. For example, large diameter sewers have continuous and high levels of flow that 

make bypassing the sewer difficult or impossible. They may contain large debris that hinder inspections 

unless the pipes are cleaned first, and they may not have been inspected for decades. Similar conditions 

exist for force mains in terms of the consequences of failure vs. the ability to inspect. 

2.2 Asset Inspection 

The primary purpose of an inspection is to define the current condition of an asset, in order to detect and 

evaluate the progression of deterioration and to make informed decisions on asset management. A well 

developed inspection plan will maximize the value of the program, while minimizing the cost of 

inspection. A detailed work plan and quality assurance project plan should also be established at this step 

to outline how the proposed inspection program would meet the program objectives. The inspection plan 

should focus on what assets to inspect, when they should be inspected, and what technologies will be used 

for inspection. Ideally, an inspection would occur at a point prior to failure where an intervention could 

effectively renew the asset. For a buried pipeline, there is limited ability to obtain a warning indicator as 

to the appropriate time and location to perform an inspection. It is this unknown state that is the inherent 

risk in managing buried assets. 

2.2.1 Selection of Assets for Inspection 

It may be considered cost prohibitive to inspect every linear foot of a wastewater collection system 

especially when confronting the need to inspect a large system with little prior inspection history. It is for 

this reason that condition assessment programs generally use a planned approach to focus on high 

consequence/high risk pipes or to utilize statistical sampling to select assets for inspection. Decisions on 

which assets to inspect should be related to the objectives and KPIs defined in the program development 

phase of the condition assessment process. For example, if the objective or KPI is to reduce SSOs, then a 

utility may focus on service lateral, which are often a large source of I/I. If the objective or KPI is to 

reduce risk of failure of high consequence pipes, then a utility may focus on pipes with higher impact and 

probability of failure, and not inspect service laterals, as they are not high risk or high consequence. 

Page 2-8 
2.2.2 Prioritization of Assets 

Two models for prioritizing assets for inspection are described below: 

•	 The National Research Council’s approach (McDonald and Zhao, 2001) utilizes an “impact 

assessment” to prioritize assets for inspection. Impact assessment is a weighted average of 

six separate impact factors: location, soil support, size, depth, sewer function, and seismic 

factors. Impact assessment can then be directly calculated in a uniform approach based on a 

weighted average. 

•	 SCRAPS (Sewer Cataloging, Retrieval, and Prioritization System) is based on the general 

approach of defining risk factors based on consequence of failure and likelihood of failure 

(Merrill et al., 2004). The term “Consequence of Failure” is defined as the impact of a failure 

in terms of repair cost, disruption to the public and economy, impairment of system 

operation, regulatory compliance, public health and safety, and damages to the environment. 

The same terminology can also be applied to the decision making process used in applying 

condition assessment to asset management. The impact of a failure must be understood and 

quantified. If the impact can be quantified in dollars, then it can be compared to both the cost 

of condition assessment and the cost of replacement and/or rehabilitation. 

2.2.3 Asset Inspection 

The type of inspection performed depends on the objective of the condition assessment program. The 

selected inspection technique needs to be consistent with the type of asset to be inspected and provide the 

information and data required to support decision making. Flow monitoring is usually utilized when 

conducting I/I studies, to evaluate hydraulic capacity and determine hydraulic restrictions. CCTV is the 

most commonly used method of inspecting sewers for structural defects; however, there are a variety of 

technologies available for this type of inspection; these technologies are discussed in-depth in Section 4.0. 

A detailed work plan and quality assurance project plan should be established; these documents ideally 

would outline how the proposed inspection program would meet the program objectives. 

2.3 Data Management 

A successful condition assessment program as part of an asset management program requires that the data 

collected are organized, analyzed, and maintained in a database system. This important step allows a 

utility to develop an understanding of trends. There are three general approaches to database management 

that have varying degrees of cost and complexity but all of which use commercially available software: 

1.	 Software specifically designed for condition assessment and asset management. 

2.	 Database software that is not specifically designed for condition assessment. 

3.	 Spreadsheet software. 

2.3.1 Condition Assessment/Asset Management Software 

There are numerous commercially available data management programs for condition assessment that 

range in level of complexity and cost. The primary component is a database to store defect coding on 

pipe segments both spatially and over time. The commercially available systems can also incorporate 

additional elements such as cost accounting, develop work orders for maintenance calls, and order parts to 

maintain required spare parts. Another useful feature is the incorporation of GIS functionality into the 

system. The GIS component highlights the geo-spatial distribution of the data, and can provide a very 

effective tool for the utility to plan subsequent inspections and/or rehabilitation activities. The benefit of 

Page 2-9 
the commercially available programs is that they are designed specifically for the intended purpose. 

However, the cost of system maintenance can be significant, as can licensing costs, depending upon 

system complexity. 

Another type of commercially available software is designed to summarize the results of a CCTV 

inspection and the resulting defect code data. This has become standard practice in the industry. The 

National Association of Sewer Service Companies (NASSCO) licenses software programs to be 

consistent using the PACP and Manhole Assessment Certification Program (MACP) rating systems, 

which are discussed in Section 2.4.2. The certification programs allow commercial providers to submit 

their pipe assessment software for evaluation and certification to ensure that their software adheres to 

NASSCO standards. It is important to verify the software has been approved to decrease the set-up time 

required to enter ranking and coding information. Pipeline inspection software is used simultaneously 

with pipeline inspection hardware to accurately document the status of sewer pipe, storm drains, or water 

pipelines. The software gives access to text data, video, and still photos all of which help the user identify 

the condition of the pipe and precisely complete a pipeline inspection. Defects can be quickly categorized 

by location, type, and severity. The software compiles this data into a searchable database which can be 

distributed into printed reports. 

2.3.2 General Database Management Software 

Utilization of commercially available database software requires a utility to design a database specific to 

their needs. The benefit would be the reduced initial licensing cost of the software. Most utilities would 

have database software as part of their professional software packages licensed for their operating system. 

Another benefit is that it may cost less to maintain than the condition assessment software described 

above. A drawback to this approach is the significant up-front work and required expertise to design a 

database system for the intended purpose. 

2.3.3 Spreadsheet Software 

Spreadsheet software is the least costly of the three systems; however, it also has the most limitations. 

This type of software is readily available and likely exists at each of the utilities. A simple yet effective 

system can be designed to collect and store data. However, spreadsheets are a flat file system and are 

very limited in usefulness as the database expands. It can become overly cumbersome if multiple spread 

sheets are required. 

2.4 Data Analysis 

The data resulting from inspection may quantify the level of service and/or structural defects. It does not, 

however, provide any ability to reduce risk or define the significance of the finding. The follow-up step is 

to process and analyze the inspection data. There are two general analysis methods used, based on the 

type of inspection performed. If flow monitoring was employed as the inspection technology, an analysis 

of hydraulic capacity is performed, using hydraulic modeling techniques. If an inspection of structural 

defects utilizing CCTV or one of the other non-destructive technologies was performed, analysis is 

generally performed by coding defects in accordance with one of the various methods available, such as 

the Water Research Centre (WRc)’s system or NASCCO’s PACP and MACP programs 

2.4.1 Hydraulic Capacity/Hydraulic Restrictions 

Hydraulic capacity is the primary performance measure for a wastewater collection system. Flow data 

gathered by flow meters has been used to guide sewer system management for at least three decades. 

Page 2-10 
Advancements in technology and software have brought a new level of condition assessment information 

to utility managers. The purpose of this section is to discuss the use of flow data as a tool in condition 

assessment. A description of improvements in flow meter technology is discussed in Section 4.5. 

Historically, flow data have been used in Sewer System Evaluation Survey (SSES) as a screening tool to 

prioritize areas for further study. Flow data presented over a period of time are useful in demonstrating 

the system impacts due to rainfall or elevated groundwater. It provides the required information to 

calibrate a hydraulic model or conduct I/I studies. The hydraulic model can then be used as a predictive 

tool to project overflow and/or surcharged conditions for various design storms. 

The following is a list of the most common indirect measurements that allow an operator to assess the 

general condition or rate of I/I: 

•	 Average Daily Dry Weather Flow includes the average flow from a sewershed, which is 

composed of the wastewater production rate and base infiltration of the system. 

•	 Base Wastewater Flow is estimated on the number and type of sewer users, domestic water 

usage records, and predicted diurnal flow variations. It equates to the anticipated flow rate of 

only wastewater in the system. 

•	 Groundwater infiltration is determined by subtracting the estimated Base Wastewater Flow 

from the Average Daily Dry Weather Flow. 

•	 Capture coefficient or percentage of rainfall that enters the sewer. 

• Relationship between rainfall and peak flow rate. 

The I/I values are valuable for planning purposes, providing a good indicator of pipe conditions upstream 

of a flow meter. As the sub-areas for which data are collected increase in size, flow data are less useful as 

a predictive tool for condition assessment. It does, however, provide the data to quantify groundwater 

infiltration and wet weather derived flow for the area tributary to the metering location. 

The real value of flow monitoring data of sewers is developing a database on long-term historic trends in 

order to determine seasonal variations and impacts of wet weather. Flow data provide the direct 

correlation needed to determine if performance measures are being attained. Flow data are also useful as 

a screening tool to determine problems areas of a system that require further study by other means. 

The traditional method of viewing flow data is hydrographs, which reveal information on condition 

upstream of flow meters. Alternatively, flow data can be viewed as scattergraphs, which provide 

information on hydraulic conditions downstream, or in the vicinity of, a flow meter. Scattergraphs are 

created by plotting flow depth versus flow velocity data. When flow meters are working correctly, a 

normal pipe curve is plotted unless normal open channel flow is not occurring. In these cases, the 

scattergraph data can be used to identify such hydraulic restrictions as silt or obstacles, bottlenecks, and 

negative grade pipe, as well as surcharged conditions. 

2.4.2 Structural Condition 

For wastewater collection systems, analysis of inspection data generally involves coding the defects based 

on both the type and severity of defects. Structural pipe defects and hydraulic restrictions encountered 

during the inspection need to be ranked by severity level based on the potential to negatively impact the 

system’s hydraulic capacity. 

The WRc, located in the United Kingdom, developed a set of standards to rank the severity of pipe 

defects found in an inspection. European authorities adopted these standards as their benchmark pipe 

defect coding standard. In 2001, NASSCO developed a set of coding standards based on the WRc system 

(NAASCO, 2001). The NASSCO PACP standards have successfully become the industry standard for 

coding pipe defects. NASSCO has also developed the MACP, which is similar to PACP but applies to 

manholes instead of pipelines. NASSCO has training programs to certify and train inspection 

Page 2-11 
professionals in PACP and MACP. NASSCO has begun work on developing a coding system for service 

laterals. 

The PACP coding system categorizes defects and features into five sections: continuous defect coding, 

structural defect coding, operational and maintenance coding, construction features coding, and 

miscellaneous features coding. For each type of defect, the PACP uses a combination of capital letters to 

describe the type of defect and a number to rank the severity of the defect. An example is “FL” for a 

longitudinal fracture. Defect codes are recorded on a standardized form along with pertinent system data 

including defect type, continuous distance of the defect, severity, size, circumferential location (clock 

location), joint number, image/video reference number, and comments. 

A brief description of the PACP defect coding system is described below: 

•	 Continuous Defect Coding: Continuous defect coding is made up of two separate coding 

classifications. The first is called “Truly”. Truly continuous defects are defects that run 

along the sewer for a minimum distance of three ft. These defects include longitudinal 

fractures and cracks. “Repeated” continuous defect coding defects are continuous defects 

that occur at regular intervals along the pipe. These usually occur at pipe joints and include 

encrustation, open joints, and circumferential fractures. Continuous defect coding can be 

used in conjunction with other types of coding to accurately describe defects on the PACP 

form. 

•	 Structural Defect Coding: Structural defect coding is made up of a number of separate 

coding classifications. This section uses coding to define the type of defects that are related 

to structural degradation of the pipe due to various reasons. The coding under structural 

defects are as follows: crack (C), fracture (F), broken (B), hole (H), deformed (D), collapse 

(X), joint (J), surface damage (S), lining failure (LF), weld failure (WF), point repair (PR), 

and brick work (BW). Under each of these subtitles there are also other letters to further 

define the type of defect. For example: HSV is for a hole with visible soil. 

•	 Operational and Maintenance Defect Coding: This section uses coding to define the type 

of defects that are related to lack of maintenance on the pipe system. Operational and 

maintenance defect coding is made up of a number of separate coding classifications as 

follows: deposits (D), roots (R), infiltration (I), obstacles (OB), and vermin (V). Under each 

of these subtitles there are also other letters to further define the type of defect. For example: 

VR designates that there are vermin, specifically, rats in the pipe. 

•	 Construction Features Coding: This section uses coding to define construction features 

located in or around the pipe system. Construction features coding is made up of a number of 

separate coding classifications as follows: tap (T), intruding seal material (IS), line (L), and 

access point (A). Under each of these subtitles there are also other letters to further define the 

type of defect. For example: AMH designates that there is an access point in the line that is a 

manhole. 

•	 Miscellaneous Features Coding: Miscellaneous features coding is made up of a number of 

separate subcoding classifications. This section uses coding to define miscellaneous (M) 

features in the pipe system. Under this subtitle there are also other letters to further define the 

type of defect. For example: MCU designates that the camera is underwater. 

The PACP uses a numerical grading system to define the severity of pipe defects. Condition grades for 

structural defects and operation and maintenance (O&M) defects are assigned based on the risk of further 

deterioration or failure. The numerical system uses numbers ranging from 1 to 5 with 1 being the best 

Page 2-12 
and 5 being the worst. The severity ranking considers the immediate defect, risk of failure, and rate of 

deterioration. 

•	 Grade 5 – Pipe segment has failed or will likely fail within the next five years. Pipe segment 

requires immediate attention. 

•	 Grade 4 – Pipe segment has severe defects with the risk of failure within the next five to ten 

years. 

•	 Grade 3 – Pipe segment has moderate defects. Deterioration may continue, but not for ten to 

twenty years. 

•	 Grade 2 – Pipe segment has minor defects. Pipe is unlikely to fail for at least 20 years. 

• Grade 1 – Pipe segment has minor defects. Failure is unlikely in the foreseeable future. 

Pipe ratings are based on the number of occurrences for each condition grade and are calculated 

separately for both structural and O&M defects for each pipe segment. Each pipe segment will be 

assigned a segment grade based on the number of occurrences of each graded defect. The graded defect 

is multiplied by the number of occurrences, and this equals the segment grade. The overall pipe rating is 

calculated by adding all of the segment grades per pipeline. The structural defects are added separately 

from the O&M grades, so each pipeline receives two separate grades. 

The PACP also uses a quick grading system, which is a shorthand method of expressing the number of 

occurrences for the 2 highest grade levels. The quick grading system uses four characters: 

1.	 The first character is the highest severity grade occurring along the pipe length. 

2.	 The second character is the total number of occurrences of the highest severity grade. If the 

total number exceeds 9, then alphabetic characters are used as follows: 10 to 14-A, 15-19-B, 

20 to 24-C and so on. 

3.	 The third character is the next highest severity grade occurring along the pipe length. 

4.	 The fourth character is the total number of the second highest severity grade occurrences, 

which is formatted the same way as the second character. 

For example, a code of 3224 would equate to two grade 3 defects and four grade 2 defects in a pipe 

segment. This also shows that no grade 4 or 5 defects were found. The quick grading system allows the 

pipe defects to be summarized in an efficient manner. As with the longhand method, structural defects 

are graded separately from O&M defects. 

2.5 Decision Making 

Decision making for condition assessment of a wastewater collection system entails understanding the 

possible risks and determining at what point a utility should intervene to avoid a failed condition with an 

unacceptable cost and/or consequence. It is important to note that condition assessment alone does not 

provide any benefit in risk reduction. The follow-up decision making process that leads to prioritization 

ranking and rehabilitation ranking followed by action to fix problems and upgrade the system is what 

leads to risk reduction. 

The purpose of this section is to highlight and summarize the decision making process, the final step in 

the condition assessment process. In addition to inspection data, the utility requires supplemental data on 

long-term asset performance to aid in the decision making process. 

Marlow et al. (2007) posed the following questions that need to be addressed to provide the required 

information for decision making: 

•	 What are the consequences of asset failure? 

Page 2-13 
•	 What are the costs to replace/rehabilitate the assets? 

•	 What alternatives exist, given the results of the condition and performance assessment (e.g., 

replacement, deferment, rehabilitation, non-structural maintenance)? 

Important definitions to consider are failed condition and service life. The American Concrete Institute 

defines service life as the period of time following installation during which all properties exceed 

minimum accepted standards when routinely maintained. 

•	 Technical service life – period of time until an unacceptable condition is reached. 

•	 Functional service life – period of time until the system element no longer provides 

functional service. 

•	 Economic service life – period of time until it becomes economically more effective to 

replace or rehab than to continue to operate in its current condition. 

The objective for the decision making model is to understand risk and to determine when to intervene to 

avoid unacceptable consequences (e.g., economic, socio-economic, environmental). However, it is not 

possible to have a robust decision making model without obtaining sufficient condition data to track pipe 

deterioration and to understand the pipe or system failure modes. 

In general terms, decisions on pipe rehabilitation/replacement can be made based on one or more of the 

following: engineering calculations, probability of failure, and remaining life estimation. 

•	 Engineering Calculations: Inspection data are interpreted deterministically. An example 

would be to calculate structural condition of a pipe segment directly based on measured 

minimum wall thickness, actual loading conditions, and existing soil bedding. A second 

example of this methodology is the calculation of hydraulic capacity. Flow data can provide 

direct measurement of actual flow conditions; and then be interpolated using a hydraulic 

model to calculate hydraulic capacity of a pipe segment under current or projected conditions. 

Both of these examples illustrate a direct calculation of the condition or performance of the 

pipe segment. If it does not meet the required design conditions or performance conditions, 

then replacement or rehabilitation is required. 

•	 Probability of Failure: This type of output would ideally provide a direct forecast of pipe 

deterioration over time. If a utility have the data to support this type of forecast, then an 

intervention could be implemented before an unacceptable level of service occurred. In 

practice, it is difficult and potentially costly to directly determine the probability of failure. 

However, the American Concrete Institute (2000) did reference studies and models to predict 

failure rate in reinforced concrete pipe. Regression forecasts and models were developed to 

predict failure of reinforced concrete pipe (RCP) based on chloride concentrations, extent of 

spalling and mechanical loading conditions, and sulfate concentration. Repeated data 

collection and analysis over time are required to obtain the decay curves based on the 

different paths to failure and the system or environmental conditions that exacerbate each 

failure mode. 

•	 Remaining Life Estimation: Remaining life estimation is commonly used to characterize 

condition of buried assets. Remaining life is defined as the duration of time until an 

unacceptable condition exists or an asset no longer meets its primary function. Standard 

coding systems are used to define condition and performance. NASSCO’s PACP system, 

discussed in Section 2.4.2, has become the standard to follow in the United States for 

wastewater pipe systems. 

Page 2-14 
A variety of decision making models have been developed for sewer assets. WERF is developing a webbased model based on remaining economic life of water and wastewater pipes. T-WARP is a software 

program that uses fuzzy logic to analyze the possibilities of pipe failure. The European Union’s 

Computer-Aided Rehabilitation Program for Sewers (CARE-S) is a software program that supports 

efficiency in rehabilitation decisions. McDonald and Zhao (2001) propose a matrix approach for decision 

making based on asset condition grades and an impact assessment rating as summarized in Table 2-1. 

The term impact assessment is defined by the authors as a weighted average of six separate impact 

factors: location, soil support, size, depth, sewer function, and seismic factors. 

Table 2-1: Condition Assessment Matrix 

Asset condition 

grade* 

Implication of asset 

condition 

Impact assessment Action Inspection 

frequency 

5 Failed or imminent failure 1 to 5 Immediate NA 

4 Condition poor, high risk of 

structural failure 

5 Immediate NA 

1 to 4 High 2 to 6 years 

3 Condition poor, moderate 

structural risk 

4 to 5 Medium 3 yrs 

1 to 3 Low 5 to 10 years 

2 Fair condition, minimal 

structural risk 

5 Medium 5 years 

1 to 4 Low 10 to 15 years 

0 to 1 Good condition 5 Not required 10 years 

1 to 4 15 to 25 years 

* Condition grade is based on WRc coding system (Manual of Sewer Condition Assessment, WRc 2003). 

NA – Not Applicable 

Source: McDonald and Zhao, 2001 

Page 2-15 
3.0 Dynamics of Wastewater Collection System Failure 

In conducting condition assessment, it is important to understand the dynamics of pipe failure including 

the level, type, and severity of a failure mechanism. Failure modes can include sudden, catastrophic 

collapse of a pipe or restricted hydraulic capacity. The purpose of condition assessment is to detect pipe 

defects which indicate the likelihood of pipe failure, as well as to assess the collection system’s 

performance. This section discusses the mechanisms of pipe failure, the various types of pipe defects, 

and the relationship between the condition of a pipe and its performance. It is important to understand 

that pipe failure and defects are highly dependent upon the pipe material, diameter, and type of sewer 

(e.g. force main, gravity line). 

3.1 Failure Mechanisms 

Pipe failures can be grouped into three general categories according to the cause of failure: hydraulic 

restrictions (e.g. blockage), hydraulic capacity, and structural condition. The following sections provide 

additional details on these failure mechanisms. 

3.1.1 Hydraulic Restrictions 

The primary function of a wastewater collection system is to convey wastewater; therefore, hydraulic 

capacity and factors that limit it are of paramount concern. Hydraulic restrictions are the most prevalent 

condition encountered in wastewater collection systems. The characteristics of untreated wastewater are 

such that accumulation of sediment, grease, and rags is a constant maintenance item. There are situations 

in larger diameter sewers, especially combined sewers, when large items create obstructions and rapid 

hydraulic restrictions. This can lead to street and basement flooding. 

Standards used for hydraulic design mandate minimum slopes for various pipe diameters to achieve 

scouring velocities that minimize debris accumulation. However, there are many external conditions that 

encourage debris accumulation (e.g. root intrusion, grease, pipe sags). 

Blockages are easily detected by visual inspection. The direct cause of a blockage sometimes is not 

evident. For most conditions, the failure rate is slow over time. A standard maintenance program for 

cleaning and flushing sewers is typically adequate to control blockages. The types of defects that fall 

within the category of hydraulic restrictions are as follows: root intrusion, sediment accumulation, and 

grease build-up. It should be noted that off-set joints and pipe sags can directly impact pipe flow thereby 

creating low velocity conditions that are conducive to solids deposition. 

3.1.2 Hydraulic Capacity 

Failure due to hydraulic capacity is defined as a pipe segment not having adequate, available capacity for 

the designed conditions. The failure condition may be caused by excessive I/I, pipe deformation, and/or 

inadequate slope. 

I/I have a direct impact on the capacity available to convey wastewater. The groundwater and storm 

water enter the collection system through direct connections or indirectly via cracks and defects. Zero I/I 

is not a realistic design objective. The hydraulic design of new sewers considers an anticipated level of 

I/I in determining pipe size. 

Pipe deformation and inadequate slope directly impact the hydraulic capacity of the pipe. Flow can be 

calculated based on the Manning’s equation for normal flow conditions: 

Page 3-16 
2/3*S1/2 Q = 1/n *A* Rh

Whereas 

Q = Flow2

 (volume per time). 

A = Cross-sectional flow area (area). 

n = Manning’s roughness coefficient. 

Rh = Hydraulic radius (length). 

S = Pipe slope. 

The mathematical relationship of change in area due to pipe deformation or inadequate slope is selfevident. A decrease in flow area and/or pipe slope will result in a proportional decrease in flow capacity. 

Failure due to hydraulic capacity is often a sign of other types of defects such as structural defects. Major 

sources of I/I can be cracks, broken pipes, leaks from manhole frames and covers, and off-set joints. Pipe 

sags and areas of inadequate pipe slope can be due to loss of pipe bedding or inadequate construction 

controls. 

3.1.3 Structural Failure 

Structural failure is caused by defects of the pipe wall and/or the soil envelope used to support the pipe. 

In general, the types of defects that are associated with structural failure include cracks, misaligned or offset joints, pipe deflection, cracked manhole frames and covers, and internal and external corrosion. 

Internal corrosion is caused by hydrogen sulfide formation, and external corrosion is due to soil 

corrosivity. 

The pipe is supported by a soil envelope that consists of the soil bedding and the cover soil. The soil 

bedding acts as the foundation for the pipe and distributes the vertical load around the exterior of the pipe 

wall. The pipe is subjected to live loads and earth loads. The goal of the bedding design is to transmit 

this load to the bedding and avoid point loads on the pipe. Loss of bedding can result in the pipe bridging 

areas of reduced bedding. This can lead to pipe deflection, pipe deformation, and longitudinal cracking. 

Increased traffic load or loss of soil cover is another cause of structural failure. 

The type and degree of failure differ by pipe material. Some pipe material (e.g. PCCP) is susceptible to 

sudden failure while others fail gradually and are easily detected by visual inspections. Typical failure 

modes for various types of pipe material used in sewer collection systems include: 

•	 Ferrous Pipe (Ductile Iron, Cast Iron, Steel) - The primary failure mode for metal pipes is 

internal or external corrosion, which leads to breaks or holes in the pipe wall. Cast iron in 

particular is brittle, making these pipes prone to cracking. Large diameter steel pipes are 

susceptible to collapse as well as corrosion. 

•	 Concrete Pipe (RCP, PCCP) - Corrosion is often a major factor in the structural failure of 

concrete pipe. RCP typically fails after the interior surface of the pipe wall has deteriorated 

to such a degree that the reinforcing steel is exposed. As the reinforcing steel corrodes, it 

swells, beginning to break up the surrounding concrete and causing failure. PCCP has a 

distinctive failure mechanism as failure occurs when the pre-stressed wires break, generally 

as a result of corrosion or direct physical damage to the pipe. 

•	 Ceramic-based pipe (Brick, Vitrified Clay Pipe (VCP)) - Brick pipes generally fail by 

collapse, often caused by weakened mortar. VCP fails when external loads create cracks in 

2

 Please note a factor of 1.49 is used when utilizing British Units. 

Page 3-17 
the material. Failure is often exacerbated by the loss of surrounding soil into the pipe after 

initial fracture leading to void formation and loss of soil support to the pipe. 

•	 Plastic Pipe (Polyvinyl Chloride (PVC), High-density Polyethylene (HDPE)) - The 

primary failure mode of plastic pipe is environmental stress cracking, which occurs from 

stress developed in a deflected pipe or due to slow crack growth, a phenomenon that occurs 

when a pipe is subjected to long duration tensile stress. Leaking joints can also contribute to 

plastic pipe failure. 

3.2 Pipe Defects 

Sewer defects are generally categorized as service or structural. Structural defects include cracks, 

fractures, breaks, deformations, collapses, joint displacements, and open joints. Service defects include 

tree roots, obstructions, debris, and encrustation. Pipe defects can also be classified by whether they are 

defects of the internal pipe surface, a pipe wall defect, a leak, or an alignment defect. Thomson et al. 

(2004) classify defects as internal pipe surface (sediment, debris, and roots), pipe wall (pipe sags and 

deflections, pits and voids, corrosion and metal loss, off-set joints, pipe cracks, broken pre-stressed wires, 

wall thickness, service connections and deteriorated insulation), leakage, and pipe support (bedding 

condition and voids). 

The most prevalent defects in wastewater collection systems are cracks/broken pipe, root intrusion, 

sediment, grease build-up, off-set joints, corrosion, frame and cover leaks, and pipe sags. However, pipe 

defects vary with the pipe material and pipe diameter. Because gravity lines and force mains are 

generally constructed of different materials, they are susceptible to different types of defects. 

Gravity pipes are usually constructed of VCP or PVC which are prone to grease build-up and joint 

misalignment/leakage. However, VCP is likely to experience cracks/breaks and root intrusion, whereas 

PVC is more likely to have excessive deflection, grade and/or alignment issues, and lateral connection 

defects. 

Unlike gravity pipes, most force mains are constructed of ferrous materials (i.e., welded steel, ductile 

iron, or cast iron) or plastic (PVC, HDPE). Large diameter force mains have also been constructed of 

PCCP. While ferrous pipes tend to experience defects similar to VCP and PVC, internal and external 

corrosion are the primary defects. Table 3-1 provides a summary of the most common pipe defects by 

pipe material from a recent utility survey (Thomson et al., 2004). 

Page 3-18 
Table 3-1: Most Common Pipe Defects Identified 

Defect 

Concrete Ferrous Ceramic Plastic Concrete pipe Asbestos cement PCCP/ CCP Cast iron/ ductile iron Steel VCP Brick PVC

HDPE 

Internal pipe surface 

Root intrusion • • • • • • • •

Grease build-up • • • • • • • •

Pipe wall condition 

Cracks/ broken pipe • • •

Internal corrosion • • • •

External corrosion • • •

Leakage 

General • • • • •

Joint leakage • •

Leaking laterals • •

Alignment/grade 

Alignment • • •

Joint misalignment • • • •

Excessive deflection • • •

Grade • •

Other 1 2 3 4 

1 – Liner separation, weld failure 3 – Lateral connections 

2 – Missing bricks, soft mortar, vertical deflection, collapse 4 – Pressure capacity (force mains only) 

Source: Thomson et al. (2004). Reprinted with permission from WERF. 

3.3 Correlations between Assessed Conditions and Performance Measures 

The measure of performance for a wastewater collection system can be based on four critical areas: 

service level, regulatory compliance, public health and safety, and environmental protection (Fleury and 

Warner, 2007). The subsections below describe how these performance measures can be correlated to 

pipe condition. 

•	 Service Level: Wastewater utilities strive to provide continuous, efficient service for their 

customers. Pipe conditions that affect service level include defects or conditions that affect 

the available hydraulic capacity to convey current and future planned wastewater flows. 

Excess hydraulic capacity in a newly constructed piping system can diminish over time due 

to many types of defects: corrosion, I/I, sediment accumulation, pipe deflections, and crossconnections. 

•	 Regulatory Compliance: Wastewater utilities must comply with existing regulations. The 

Clean Water Act (CWA) prohibits discharges of pollutants to waters of the U.S., unless 

authorized by a National Pollutant Discharge Elimination System permit. Unpermitted 

discharges from the sanitary sewer system constitute a violation of the CWA. Noncompliance with the SSO regulations, specifically the CMOM provisions, will result in 

enforcement actions including mandated O&M programs and fines. Pipe conditions that 

affect regulatory compliance may include defects or conditions that cause sewage overflows 

or back-ups. 

Page 3-19 
•	 Public Health and Safety: Wastewater utilities protect public health and safety by 

minimizing conditions where the public can be exposed to untreated sewage such as receiving 

waters used for drinking water sources, fishing, and/or contact recreation such as swimming. 

Pipe conditions that affect protection of public health include defects or conditions that cause 

sewage overflows, back-ups or catastrophic pipe failure. 

•	 Environmental Protection: Pipe failure may cause extensive property damage and/or 

discharge of untreated sewage. Failures of large diameter pipes and force mains contribute to 

the formation of sinkholes that may lead to damage and/or disruption to roadways and 

utilities, as well as the creation of hydraulic restrictions. Pipe conditions that affect 

environmental protection efforts are similar to those listed above—defects or conditions that 

cause sewage overflows, back-ups, or catastrophic pipe failure. 

Utilities use pipe condition information to assess how well they are meeting each of these performance 

measures and to identify and prioritize system needs. The goal is to provide the best possible service in a 

cost-effective manner. Utilities need to know what is an acceptable level of performance that can provide 

regulatory compliance, environmentally acceptable performance, and operational effectiveness at the 

lowest possible life cycle cost? Inspection and condition assessment provide key information for helping 

the utility address these questions and balance system needs and costs. 

Page 3-20 
4.0 Inspection Technologies 

Inspection technologies and their use in condition assessment for wastewater collection systems are 

presented in this section. Each technology is briefly described, and commercially available and emerging 

products utilizing the technology are discussed. Table 4-1 provides a summary of typical applications for 

each technology. 

Table 4-1: Inspection Technology Overview 

Technology Sewer type 

Pipe materialPipe diameter

Defects detected 

GravityForce main Lateral Internalcondition Pipe wall Leakage Pipe support 

Camera 

Digital cameras • Any 6-in.­

60-in. • • •

Zoom cameras • Any >6-in. • • •

Push-camera • Any 1-in.­

12-in. • • •

Acoustic 

In-line leak detectors • • Any >4-in. •

Acoustic monitoring 

systems • PCCP >18-in. •

Sonar/ultrasonic • • Any >2-in. • •

Electrical/electromagnetic 

Electrical leak location • • • Nonferrous >3-in. •

Remote field eddy current • • • Ferrous, 

PCCP >2-in. • •

Magnetic flux leakage • • • Ferrous 2-in.­

56-in. •

Laser

Laser 

profiling • • Any 4-in.­

160-in. • •

Innovative technologies 

Gamma-gamma logging • • • Concrete Not yet 

defined •

Ground penetrating radar • • • Any Not yet 

defined • •

Infrared thermograph • • • Any Not yet 

defined • •

Micro-deflection • Brick Not yet 

defined • •

Impact echo/SASW • Brick/ 

Concrete >6-ft. •

Page 4-21 
4.1 Camera Inspection 

CCTV inspection is a very effective method of evaluating and creating a permanent video record of 

underground pipe conditions. The visual inspection of sanitary sewer lines enables a CCTV operator to 

locate and identify specific defects that contribute to the infiltration of groundwater into the collection 

system and exfiltration of sewage into the substrate surrounding a pipeline. This is a well established and 

common industry method for pipeline assessment. In a recent survey report (Thomson et al., 2004), 

100% of survey respondents from large wastewater utility districts relied on CCTV as their primary 

method of collection system inspections; hence, it is not surprising that the critical gaps identified in this 

survey parallel the limitations of CCTV inspection. CCTV provides a means to inspect a pipeline that is 

either too small or hazardous for direct human entry inspection. The primary disadvantages to the 

technology are that it only provides a view of the pipe surface above the waterline and does not provide 

any structural data on the pipe wall integrity or a view of the soil envelope supporting the pipe. 

The technology and level of ancillary equipment used for CCTV inspection of sewer systems varies 

significantly based on the diameter of the line being inspected. In general, CCTV technology uses a 

video camera with lighting to provide a visual recording of the inside condition of a pipeline. The means 

to convey the camera through the pipeline vary in complexity from simple pushrod cameras (pushcams) 

to complex remote controlled robot crawlers. The level of optical control on the camera also varies in 

complexity. The ability to pan, tilt, and zoom has become the industry standard for sewer inspection 

because it allows the operator to gain a full circumferential view of the pipe. 

Data obtained from CCTV inspection include: 

• Evidence of sediment, debris, roots, etc. 

• Evidence of pipe sags and deflections. 

• Off-set joints. 

• Pipe cracks. 

• Leaks. 

• Location and condition of service connections. 

As noted above, CCTV technology does have limitations due to its ability to only provide a visual 

representation of the inside surface of a pipe above the waterline. Additionally, the quality of defect 

identification and pipe condition assessment using CCTV is highly dependent on many factors including 

operator interpretation, picture quality, and flow level. In terms of benefits, it is a cost-effective 

technology providing the broadest base level of data used in condition assessment. For example, many 

technologies exist (as described in later section) that provide data on the structural condition of the pipe 

wall, and other technologies exist that can determine the condition of the soil surrounding the pipe. 

However, these technologies are unable to provide visual data on leaks, location of service laterals, and 

sediment and debris accumulation. It is for this reason that CCTV will remain an important inspection 

tool in any condition assessment program for wastewater collection systems. 

The following sections present innovative technologies specific to CCTV and its use in condition 

assessment for wastewater collection systems. Each technology will be briefly described, noting 

manufacturers and/or providers of the technology and typical applications. The technologies described in 

this section include: 

• Zoom Camera Inspection. 

• Digital Scanning. 

• Camera Deployment. 

Page 4-22 
4.1.1 Zoom Camera Inspection 

Like traditional CCTV inspection, zoom camera inspection technology involves the generation of still 

imagery and/or recorded video imagery of a pipe. The key difference is that in zoom camera inspection, 

the camera mount is stationary. The technology does not require the camera equipment to pass though the 

entire length of the pipe segments being inspected. Instead, the camera is mounted either on a truck, 

crane, pole, or a tripod. The equipment is then lowered into a manhole to perform the inspection and the 

camera “zooms” down any pipe entering or exiting the manhole. 

Historically, zoom cameras have been utilized to perform manhole inspection and inspect a few ft down 

the pipe utilizing a camera mounted on the end of a telescopic pole. This technology is commonly 

referred to as a down look camera. Newer zoom cameras can pan 360 degrees and zoom up to 100-ft. in 

6-in. diameter pipe and up to 700-ft. for larger pipe diameters. 

This technology involves setting up the zoom camera at each manhole and inspecting the manhole and 

pipes. Potentially, the technology could allow for the inspection of an entire section of pipe from one 

manhole to the next. Zoom camera inspection has some of the same limitations as traditional CCTV pipe 

inspection in that it cannot inspect what is beneath the fluid being conveyed through the pipe. It is not 

designed to replace conventional CCTV systems, but rather to screen and prioritize pipes for further 

conventional CCTV work and/or cleaning pipelines. The technology does not provide the detailed visual 

evaluation of conventional CCTV. The primary advantage to the technology is improved production rate. 

The set-up eliminates the need for cleaning prior to the inspection, as well as the inevitable down-time 

associated with an obstruction to a crawler mounted camera. An inspection crew can move through a 

service area in an expeditious manner and highlight segments requiring a more detailed inspection. 

Zoom camera inspection is a very efficient, cost-effective method of performing manhole inspections, 

which has been its primary use. It is, however, limited in its ability to inspect pipe segments. Image 

resolution, lighting, and limitation in optical zoom are the primary disadvantages of this technology. The 

technologies described below attempt to overcome these limitations with improvements to lighting and 

zoom ability. This technology also increases the production rate of sewer inspections, as it collects data 

at a speed several times faster than traditional CCTV inspection. This is in part because pipes generally 

do not have to be flushed and cleaned prior to inspection. 

Zoom camera inspection is only useful for inspecting gravity sewers because its access to the sewer is via 

a manhole. Force mains and/or service laterals do not have the required access points to deploy this 

technology. As with all camera inspection technologies, zoom camera inspection can be used with any 

pipe material. 

Zoom camera inspection services are available from a variety of service providers. Both regional and 

national service providers have the ability to provide this service. It is not known if the use of the longer 

range cameras with increased zoom capabilities is a commonly used inspection tool in the industry. 

Provided below is a description of four manufacturers of zoom cameras used for the inspection of gravity 

sewers. 

No new zoom camera technologies under development have been specifically identified as emerging 

technologies. Likely, the identified manufacturers will continue product development and increase 

optical and digital zooming capabilities. It is also likely that the technology will be equipped with a 

digital inspection system as described in Section 4.1.2. Table 4-2 provides a summary description of the 

zoom camera technology. 

Page 4-23 
Table 4-2: Zoom Camera Inspection Summary 

SUMMARY 

Sewer type Gravity sewers only 

Material Any 

Pipe size > 6-in. 

Defects detected Cracks, leaks, root intrusion, overall surface condition of pipe/manholes 

Original application Manhole inspection 

Status Commercially available 

Advantages High production rate, effective/efficient at prioritizing segments requiring 

more detailed inspection/maintenance 

Disadvantages Inability to inspect manhole to manhole for average diameter lines, potential 

to miss significant defects 

CUES IMX - Truck Mounted Zoom Camera 

The CUES-IMX truck-mounted zoom camera provides video inspection for manholes and pipelines. The 

CUES-IMX camera offers imaging technology with a 25:1 optical zoom that is stabilized and remotely 

controlled by a telescopic boom. The camera can record images from up to 300’ into the pipeline. The 

camera mounting fork is designed to pan the camera head 360° continuously, tilt mechanically 45° up or 

90° down, and tilt optically 166°. The camera imager, optics, mechanics and electronics are housed in a 

damage resistant, waterproof, rugged enclosure that is 7-in. in diameter and 16-in. in length. The CUESIMX system includes the camera, high intensity discharge lighting heads, mast system and controller. 

The manufacturer indicates that the system can be mounted within an inspection van, all-terrain vehicle, 

or a trailer. 

The system is equipped with data collection, GIS software and global positioning system (GPS) 

equipment. The GIS software and GPS equipment are used to create sewer maps in the field and create 

an asset management database for the system. Defects detected during the inspection can be stored in a 

database along with photos and video clips. All data is geo-referenced to the field collected GPS 

coordinates. This is common to the industry and the subject of further discussion in a later section. 

The objective of the CUES-IMX camera system is to increase the production rate of the inspection 

process, as compared to traditional CCTV. The manufacturer indicates that an inspection process using 

zoom technology has a production rate of five to eight times higher than traditional CCTV and is a useful 

tool to efficiently characterize a collection system and prioritize segments for further inspection and/or 

cleaning. Inspections using the CUES-IMX camera provides mapping, inventory and condition 

information that can be used immediately to reduce system operation and maintenance issues by quickly 

identifying areas of high-risk due to blockage or structural defects. The risk of backups or overflows can 

be assessed and addressed rapidly. 

GE Technologies - Ca-Zoom PTZ and QuickView 

GE Technologies offers three truck-mounted Everest Ca-Zoom Pan-Tilt Zoom (PTZ) cameras for sewer 

inspection. Each camera has a different PTZ camera head. The PTZ 140 has a 300:1 zoom capability 

(optical 25:1, digital 12:1) and is equipped with two high-power 35-watt lights. The camera has the 

ability to record imagery up to 250 ft down a pipe segment with diameters between 15 in. and 60 in. The 

PTZ100 has 40:1 zoom capability (10:1 optical, 4:1 digital), and four 5-watt light-emitting diode (LED) 

lights. The PTZ270 also has a 40:1 zoom capacity, but has eight 5-watt LED lights. 

The smaller hand-held QuickView unit is a pole mounted camera with a total zoom capability of 216:1 

(18:1 optical, 12:1 digital). It has the ability to zoom to between 75 and 250 ft within pipe diameters of 6 

in. to 60 in. The unit is mounted on an 18 foot telescoping pole. 

Page 4-24 
The benefits and limitations of these cameras are similar to those of the CUES-IMX camera system as 

described above. 

CTZoom Technologies - PortaZoom 

Innovative Technology Products, Inc. offers sewer inspection with the PortaZoom camera, manufactured 

by CTZoom Technologies. The PortaZoom is housed in a compact enclosure, just 6 in. in diameter. The 

camera pans more than 350° and has a 312:1 zoom capability (26:1 optical, 12:1 digital). The camera has 

full-circumference integrated lighting, including peripheral lighting to reduce shadows. The PortaZoom 

is operated by a computer, joystick and keyboard. The PortaZoom can be mounted to any vehicle or 

hand-held pole, and can zoom approximately 100 ft to 200 ft into pipes. 

AquaData, Inc. - AquaZoom 

AquaData Inc. also manufacturers zoom camera inspection equipment. They manufacture the AquaZoom 

system though it is not commercially available. The AquaZoom can be used on pipes with diameters of 6 

in. or larger and can inspect pipelines for approximately 100 ft. It is normally mounted on either a truck 

or tripod, which is claimed to provide better stability compared to pole mounted devices. It also utilizes a 

built-in control center and video recording equipment to perform pipe inspections. 

Aries Industries – HC3000 Zoom Pole Camera 

The Aries HC3000 Zoom camera has a 432:1 zoom ratio (36:1 optical, 12:1 digital). The camera has two 

LED lights, and is mounted on a 6-foot to 18-foot telescoping pole. The camera can view up to 100 ft 

into the pipeline being inspected. The image is transmitted via radio frequency technology to a media 

case, which houses a radio frequency receiver and monitor. A small portable monitor is also available for 

viewing the images as the camera zooms down the pipe. The pole mounted device provides easy 

portability and rapid setup. 

4.1.2 Digital Scanning 

Digital scanning is a state-of-the-art technology within the camera inspection industry. Like conventional 

CCTV, digital cameras are transported through sewer lines using self-propelled crawlers. Unlike 

conventional CCTV systems, digital scanning uses one or two high-resolution digital cameras with wideangle lenses in the front, or front and rear, section of the housing. During pipe inspections, parallel 

mounted lights are triggered at the same position in the pipe. The hemispherical pictures scanned are put 

together to form 360° spherical images. There is one specific manufacturer that utilizes a single camera 

with a wide angle lens to accomplish the same result. 

During the scanning process, data are transmitted to a surface viewing station where it can be viewed in 

real-time and recorded for later evaluation. The major advantage to digital scanning technology is that it 

is possible for the data to be assessed independently of the real-time sewer inspection. By comparison, 

conventional CCTV relies on a camera operator to pan, tilt, and zoom into critical areas for further 

review. The image, as controlled by the operator, is stored. Therefore, if the operator does not see a 

defect, the camera is not stopped for further investigation. 

Digital scanning develops a full digital image of the pipe segment. This allows the individual reviewing 

the images to control the direction of the PTZ features and to stop the image at any point to capture video 

clips and images. The inner pipe surface can be “unfolded” providing a view of pipe conditions, which 

permits computer-aided measurement of defects and objects. Digital scanning provides a more consistent 

and complete assessment of pipe condition. It provides a second level of quality control in the review 

Page 4-25 
process and allows other individual(s) involved in the process to gain insight into the pipe condition (e.g., 

designers, rehabilitation contractors, and utility owners). 

Digital scanning technology is primarily used for gravity lines in the 6-in. to 60-in. diameter range. Its 

applicability for use in inspecting sewer laterals is limited since laterals are typically less than 6 in. in 

diameter and access is generally through a small diameter clean-out. It is also limited in its ability to 

inspect force mains. Like conventional CCTV technology, digital scanning is only able to provide useful 

images above the waterline; force mains would have to be taken out of service and drained before digital 

recording. Access to force mains also typically restricts the use of digital and CCTV technology. Force 

mains are pressurized and do not have access manholes to insert CCTV equipment. Digital scanning can 

be used with any pipe material. Table 4-3 provides a summary description of the digital camera scanning 

technology. 

Table 4-3: Digital Camera Scanning Inspection Summary 

SUMMARY 

Sewer type Gravity sewers, limited applicability for force mains and service laterals 

Material Any 

Pipe size 6-in. to 60-in. 

Defects detected Cracks, leaks, root intrusion, overall condition of pipe 

Original application Inspection of piping 

Status Commercially available, new applications under development 

Advantages Increased QA/QC control, additional project personnel able to review/control 

data imagery, able to make digital measurements of defects, can compare 

data directly from one inspection to the next 

Disadvantages More costly then CCTV, lower production rate compared to traditional 

CCTV, only works above waterline. 

Digital scanning camera systems are available from a variety of vendors. Several commercial 

applications are specifically designed for the investigation of water, storm drain, and sewer pipelines. 

The following are descriptions of some of the products available from several vendors. 

Blackhawk-PAS - Sewer Scanning Evaluation Technology (SSET) 

SSET was developed in Japan in 1994, and introduced through field trials in the United States in 1997. 

The third-generation SSET was refined by Blackhawk-PAS for commercial marketing. SSET uses two 

digital image capture devices mounted on a remotely controlled tractor. One of the cameras records a 

forward view of the pipeline while the other camera scans the side of the pipe to create a spiral, 

perpendicular view. SSET can be used in pipes ranging from 8-in. to 36-in. diameter, operating at a rate 

of approximately 13 ft per minute. 

RapidView – IBAK, USA - Panoramo 

The RapidView-IBAK, USA Panoramo system was developed by IBAK Helmut Hunger GmbH & Co. 

KG of Kiel Germany in partnership with RapidView, LLC. The application was first developed and used 

in 2002. The first application in the United States was in 2007. 

The Panoramo system uses two high-resolution digital photo cameras with 186° wide-angle lenses fit into 

the front and rear section of the housing. During pipe inspections, parallel mounted xenon flashlights are 

triggered at the same position in the pipe. The hemispherical pictures scanned are put together to form 

360° spherical images. The Panoramo can scan 8-in. to 48-in. diameter pipes at a speed of up to 70 ft per 

minute in forward or reverse motion. 

Page 4-26 
During the Panoramo scanning process, the data are transmitted digitally to the inspection vehicle and are 

at the operator's disposal. The scans can be viewed as live pictures for orientation purposes and for 

locating any obstructions. In addition, the data are stored in the form of "PANORAMO films", on 

removable hard disks or digital video discs (DVDs). 

This image scanning method makes it possible for the pipe inspection to be assessed by personnel away 

from the field. The reviewer has the ability to pan, tilt, or zoom in on potential defects as if in the truck 

with the field crew. The reviewer can stop at any position, turn a full circle, zoom, and complete the data 

analysis. An unfolded view of the inner pipe surface which is available simultaneously gives the reviewer 

a rapid view of the state of the pipe and permits computer-aided measurement of the position and size of 

objects. The Panoramo system works in conjunction with WinCan Scan Explorer Software Version 8. 

Envirosight - DigiSewer 

The Envirosight DigiSewer system was originally developed by DigiSewer and manufactured by IPEK 

(provider of crawlers and cameras to Envirosight). The DigiSewer was originally designed to be used for 

borehole inspection and was first used in Europe in 2003. It was officially released to the North 

American market in April 2007. 

The DigiSewer uses one high-resolution photo cameras with 180° wide-angle fisheye lens, integrated into 

the front of the rover crawler. The DigiSewer can scan pipes from 6-in. to 60-in. diameter at a scan speed 

of 70 ft per minute. The DigiSewer can scan pipes over a length of approximately 650 ft. 

Emerging Technologies 

No digital scanning applications have been specifically identified as emerging technologies. Likely, the 

identified manufacturers will continue product development and increase optical and digital zoom 

capabilities. The technology is four to five years old in Europe and Asia; however it has a limited history 

in North America. The manufacturers and users listed above are constantly developing new ways to use 

these products. Our research indicates that future research will focus on enhancements to the software 

used for defect recognition and digital defect measurements. RapidView and Envirosight are developing 

manhole inspection capabilities with the use of the digital scan cameras. Envirosight is also planning to 

increase the scan distance to approximately 1,650 ft by fall 2008 and provide improved scanning rates. 

4.1.3 Camera Deployment 

In a CCTV inspection, cameras are deployed into pipelines in a variety of ways. Mobile robots called 

crawlers or tractors are available in a variety of sizes and configurations, thus enabling their use in a host 

of pipes sizes. These are typically introduced into the sewer via a manhole. Cameras can also be 

mounted to float rigs for inspecting large diameter pipes partially filled with water. Pushrod cameras are 

typically used in smaller diameter pipes (6 in. and less) such as service laterals and are typically 

introduced into the sewer through a cleanout. 

This section describes innovations to vehicles used to carry CCTV cameras as well as technologies that 

can be added to the conventional camera vehicles to further assist in CCTV inspection. 

A variety of innovations have been applied to the tractors or crawlers which carry CCTV cameras. These 

innovations include extra long range tractors/floats compared to the typical applications in use, smaller 

than typical tractors that can be used for some laterals, tractors that are able to dispatch smaller lateral 

cameras from the main line, and segmented robots that can bend around odd angles in small diameter 

pipes. 

Page 4-27 
Different camera tractor innovations are available from a variety of vendors. Several commercial 

applications are specifically designed for the investigation of water, storm drain, and sewer pipelines. 

Pushcams are used almost exclusively in smaller diameter sewers such as service laterals. Tractor 

innovations have been broken down into four groups: small diameter tractors, long range tractors, 

segmented tractors, and lateral launchers - tractors that can launch lateral cameras off of the main 

inspection vehicle. 

Pushcams 

Pushrod camera, or pushcam, technology involves the inspection of pipeline via a small diameter camera 

mounted to a pushrod and reel setup which produces video of the pipeline. This technology is primarily 

designed for laterals and small diameter force main applications. Conventional pushcams use straight 

view cameras capable of inspecting pipes of 2-in. or greater. Advancements include pushcams capable of 

inspecting pipes smaller than 2-in. as well as steerable and pan/tilt pushcams. 

Pushcams are typically used in an environment where it is otherwise impossible to get photographs or 

video footage such as a small diameter water, sewer, or drain pipes. Typically, they are used in 

applications where crawlers/robotic camera vehicles are unable to function due to their larger size. 

Conventional pushcams systems are comprised of a camera/probe, cable/reel, and 

computer/recorder/controller. The probe used to advance the camera is usually a semi-rigid rod, 

constructed of fiberglass. The primary limitations are image quality, lighting, and ability to move past 

obstructions. Table 4-4 summarizes a variety of commercially available pushcams. 

Table 4-4: Pushcam Product Comparison 

PRODUCT 

(VENDOR) 

PIPE 

DIAMETER 

INSPECTION 

LENGTH 

NOTES 

CrystalCam Push Camera 

(Inuktun) 

>2-in. High resolution low lux camera – highly 

effective in low light environments. Can be 

tractor mounted, can be used as a reverse 

camera 

Flexiprobe 

(Pearpoint) 

1-in. to 8-in. 500-ft 

Hydrus 

(Rapidview-IBAK, USA) 

>2-in. Straight view camera only 

Orion 

(Rapidview-IBAK, USA) 

>4-in. Pan and tilt functions 

Orion L 

(Rapidview-IBAK, USA) 

>4-in. Pan and tilt, includes “steer stick” allowing 

device to be steered around bends or turns 

Push Camera 

(Insight Vision) 

1-in. to 12-in. 300-ft Uses Clearview line of camera heads, large 

10.4 in. LCD monitor 

Tractors/Crawlers 

Tractors and crawlers are mobile robots used to deploy CCTV through a pipeline. Most are wheeled or 

tracked, and are tethered via a cable to a controller unit located near the point of entry to the sewer 

system. Conventional CCTV inspection tractors are larger vehicles that are not able to get into smaller 

pipes or laterals. Many of the tractors are not steerable and can only inspect pipe runs of 300 to 500 ft. 

Advancements in technologies now include lateral launchers that are able to deploy smaller diameter 

pushcams into laterals; small diameter tractors that can be deployed in pipes as small as 4 in. in diameter; 

long range tractors that can inspect pipes at great distances from the point of entry; and segmented robots 

that can bend around odd bends or angles in small diameter pipes. Tables 4-5, 4-6, and 4-7 summarize a 

selection of commercially available innovative tractor and crawler technologies. 

Page 4-28 
Table 4-5: Lateral Launcher Product Comparison 

PRODUCT 

(VENDOR) 

MAINLINE LATERAL 

Pipe NOTES

diameter 

Inspection 

length 

Pipe 

diameter 

Inspection 

length 

IBAK LISY 150-M 

(RapidView-IBAK, USA) 

>6-in. Tungsten carbide 

wheel for grip 

LAMP 6-in. to 24­ 2-in. to 6­ >80-ft 

(CUES) in. in. 

Lateral Evaluation Television 

System 

(Aries Industries) 

>8-in. 800-ft 3-in. to 6­

in. 

80-ft Can ID pipe locations 

with locator beacon 

Lateral Inspection System (RS 

Technical Services) 

8-in. to 24­

in. 

1,000-ft 4-in. to 8­

in. 

100-ft 

Table 4-6: Small Diameter Tractor Product Comparison 

PRODUCT 

(VENDOR) 

PIPE 

DIAMETER 

INSPECTION 

LENGTH 

NOTES 

ELK T100 Mini 

(Pearpoint) 

4-in. to 10-in. 500-ft 

KRA 65 

(RapidView – IBAK, USA) 

>4-in. Steerable, electric stabilizing function 

Mighty Mini Transporter 

(RS Technical Services) 

4-in. to 12-in. 500-ft 

Rovver 100 

(Environsight-IPEK) 

4-in. to 12-in. 660-ft Steerable, PVC wheel with titanium spikes for 

traction 

Versatrax 100 

(Inuktun) 

>4-in. 600-ft Tracked crawler 

Xpress Silver-Bullet Crawler 

(Insight Vision) 

4-in. to 15-in. 600-ft 4-wheel drive crawler 

Table 4-7: Long Range Tractor Product Comparison 

PRODUCT 

(VENDOR) 

PIPE 

DIAMETER 

INSPECTION 

LENGTH 

NOTES 

Versatrax 300 VLR 

(Inuktun) 

>12-in. 6,000-ft Modular construction for onsite customization, 

optional reverse camera can be mounted on 

crawler 

Responder 

(RedZone) 

>36-in. 5,280-ft Skid steer enabled tractor, Kevlar reinforced 

buoyant cable, submersible to 500-ft 

Segmented Robots 

Electromechanica, Inc. designs custom inspection robotics and other applications on an as needed basis. 

For example, the client may have a specific type of small diameter pipe system containing tees or wyes, 

or other angles that a typical tractor or crawler would not be able to navigate. One such development is 

the Internal Pipe Inspection Robot. This design uses a unique “inchworm” movement which optimizes 

movement within the pipe. The robot itself consists of three arm linkages that expand radially to force the 

different segments to grip the inside of the pipe and move it along. The multiple segments also can be 

useful in overcoming obstacles or looking down laterals. The robot uses pneumatic cylinders to provide 

force to move the robot through the pipe. The robot can be outfitted with cameras, sensors or tools to 

achieve many different types of jobs in pipes including pipe inspection. As stated above, this is not a 

commercial product, but one that must be custom ordered for the client’s specialized needs. 

Page 4-29 
Emerging Technologies 

•	 Pushcams - The IPEK Agilios pushcam system was developed for small diameter pipes and 

has pan/tilt capability. It works in conjunction with the vision control unit and is battery 

powered. 

•	 Autonomous Crawlers - An autonomous crawler does not require a real-time remote 

operator. The crawler’s behavior is programmed in advance of deployment. The vehicle is 

programmed to cue off of particular environmental landmarks. For instance, RedZone 

Robotics, a Pittsburgh, Pennsylvania based company, has designed a robot that constantly 

monitors the diameter of the pipe as the robot progresses through the pipe. Infrared sensors 

atop the vehicle sense when the distance to the roof of the pipe alters radically, which the 

robot then interprets as a manhole. The vehicle may be programmed to stop at the first 

manhole it encounters, or stop after encountering some specified number of manholes. 

Autonomous crawlers are beginning to enter the marketplace. 

•	 Autonomous Floaters - Automatika, Inc. based in Pittsburgh, Pennsylvania, is developing 

the prototype of a neutrally buoyant, untethered pipe inspection robot called PipeEye. The 

robot is a 12-in. sphere designed to float in pipes greater than 24 in. in diameter. Cameras 

and lights will operate above the waterline, and ultrasonic transducers will operate below the 

waterline. The PipeEye system is derived from an oil/gas pipeline inspection module codeveloped by Automatika and Shell Oil. Currently, the system does not yet have a product 

status. 

4.2 Acoustic Technologies 

Acoustic technology in general terms uses measuring devices to detect vibrations and/or sound waves. In 

pipeline assessment, acoustic sensors are used to detect signals emitted by defects and are utilized by a 

variety of commercially available products. Acoustic technologies are used extensively for inspection of 

water mains; therefore, this category of inspection technology can also be used for force main inspection. 

There are three distinct classifications of acoustic technologies: 

•	 Leak detectors, which are used to detect the acoustic signals emitted by pipeline leaks. 

•	 Acoustic monitoring systems, which are used to evaluate the condition of PCCP. 

•	 Sonar, or ultrasonic, systems, which emit high frequency sound waves and measure their 

reflection off the pipe wall in order to detect a variety of pipe defects. 

Table 4-8 summarizes these classifications of acoustic technologies. 

Page 4-30 
Table 4-8: Acoustic Technology Summary 

SUMMARY IN-LINE LEAK 

DETECTORS 

ACOUSTIC MONITORING 

SYSTEMS SONAR/ ULTRASONIC 

Sewer type Force mains, gravity 

sewers 

Force mains Force mains, gravity sewers 

Material Any PCCP Any 

Pipe size >4-in. >18-in. >4-in. 

Defects detected Leaks Broken pre-stressed wires Pipe wall deflections, 

corrosion, pits, voids, and 

cracks, debris 

Original application Leak detection in 

pressurized water lines 

Monitoring PCCP water lines Maritime use 

Status Commercially available 

for sewer inspection 

Commercially available for 

sewer inspection 

Commercially available for 

sewer inspection 

Advantages Can detect very small 

leaks. 

Useful as a screening 

technique prior to more 

detailed inspection 

Suitable for pipes of any 

material and a wide range of 

diameters 

Disadvantages Requires minimum flow to 

be carried through pipe 

Only detects general distress Only inspects pipe below 

the waterline 

4.2.1 Leak Detectors 

Leak detectors are devices used to detect the sound or vibration produced by leaks in pressurized 

waterlines or in sewers. These include hand-held listening devices such as listening rods, underwater 

microphones (also known as aqua phones, sonoscopes, water phones or hydrophones), and geophones 

(ground microphones); leak noise correlators; and in-line devices which collect information on leaks 

remotely. Listening devices and leak noise correlators are widely available, and have been used for leak 

detection for decades. In-line leak detectors are a more recent advancement in the use of acoustic 

technology for condition assessment of pipes. 

The simplest forms of leak detector are mechanical listening devices. These include listening rods and 

aquaphones, which are both metallic rods fitted with an earpiece. These devices are operated by placing 

the rod in direct contact with pipes, allowing the device operator to hear leaks through the earpiece. 

Geophones are another type of listening device; these are placed on soil or pavement above a pipe, 

allowing the operator to hear the sound from leaks as it is transmitted through the soil. Listening rod and 

aquaphones may also be electronic, these are similar to the mechanical devices described above but also 

include special elements such as noise filters, adjustable amplifiers, and sensing elements such as 

piezoelectric materials; leaks can be detected either by operators listening through headphones or in some 

cases by soundmeters that can store the sound levels emitted by leaking pipes. 

Leak-noise correlators are a more complex and accurate type of leak detector, which have been used for 

leak detection since the 1980s. These are computer-based devices which are used to measure sound or 

vibration at two points on a pipe, on either side of a suspected leak. Depending on the device, the 

measurements are made by a vibration sensor such as an accelerometer attached to pipe contact points or 

an underwater microphone which is inserted into the pipe itself. Signals detected by the sensor are 

wirelessly transmitted to the correlator, which pinpoints the location of leaks based on the time lag 

between the leak signals measured from the two points. 

The most complex forms of leak detectors are in-line systems, which are deployed in a pipeline and 

continuously monitor leakage. The rest of this section focuses on these systems. There are several 

Page 4-31 
commercially available in-line leak detectors which utilize acoustic technologies for pipe condition 

assessment. Both regional and national service providers have the ability to evaluate wastewater systems, 

although the technology is far more prevalent in its use for condition assessment of water distribution 

systems. Provided below is a description of several of these products. 

Sahara® – Pressure Pipe Inspection Company 

The Sahara system was originally developed by WRc for detecting leaks in pressurized water lines, and is 

a proven technology for that application. In the United States, the Sahara system has begun to be used for 

wastewater collection systems. A series of pilot studies using the Sahara for wastewater pipeline leak 

detection were conducted in the United Kingdom in 2005 and North America in 2006. The system is now 

available in the United States from the Pressure Pipe Inspection Company. 

The Sahara system consists of a sensor head and a hydrophone, which is an electrical instrument used to 

detect or monitor sound under water. The sensor head is inserted into a pipe through any access point 

greater than three inches in diameter. As the sensor head is transported through the pipe line by product 

flow, acoustic signals are picked up at the surface by the hydrophone. The signal is then fed through a 

cable, and from there to processing equipment. The system operator is able to hear signals from the 

system directly as well as view the signal on a computer with spectrogram software. The system locates 

leaks by identifying acoustic signals; the size of leaks can be estimated based on the acoustic signal 

recorded by the device. 

The Sahara system can be used in pipelines of any material to detect leaks as slow as approximately 0.25 

gallons/hour. It can be used to inspect force mains 4-in. in diameter and larger. The system requires a 

minimum flow velocity of approximately 3 ft/s to ensure the device can move though the pipe. 

Additionally, pressure within the pipe must be between 10 and 150 psi in order for the system to 

recognize leaks. 

Smartball® - Pure Technologies 

The Smartball® leak detector was made commercially available by Pure Technologies in 2005. It is a 

proprietary system maintained by Pure Technologies. The technology is only used for inspections of 

pressure pipelines. It can be used for any pipeline material. 

The Smartball® consists of a neutrally buoyant, foam ball equipped with an instrumented aluminum inner 

core. The aluminum inner core contains several sensors including an acoustic sensor, accelerometer, 

magnetometer, temperature gauge, and pressure gauge. The inner core also contains a microprocessor 

with an ultrasonic transmitter. The system is powered by a DC battery and contains a data logger. The 

Smartball® can be inserted into a pipeline and travel with the water flow for more than twelve hours, 

collecting data on the collection system with a single deployment. The Smartball® has a diameter of 2.6­

in. and can be used on a pipe with 10-in. or greater in diameter. A minimum flow velocity of 1.64 ft/sec 

is required to convey the sensor. 

The system can be inserted into a full or partially full pipe, and is carried along by the flow of water or 

wastewater. The Smartball® is silent; therefore its acoustic sensor can detect the sound of very small 

leaks in the pipeline. As the Smartball® passes through the pipe its progress can be tracked by a variety 

of methods, allowing for leak location to be determined within one meter of accuracy. The system can 

operate for up to twelve hours before it is retrieved and data downloaded. 

LxSentry – LxSix Photonics, Inc. 

The LxSentry pipeline monitoring system was recently introduced by LxSix, Photonics Inc. LxSentry is a 

highly sensitive fiber optic system designed to detect leaks in gas pipelines. Acoustical sounds are 

Page 4-32 
classified by the proprietary Red Alert software, which is capable of distinguishing between pipeline 

leaks, tampering, intrusions, and machinery and vehicles operating in the pipeline vicinity. Minimal 

information on the details of the operation and use of this product is currently available. No information 

was available on the use of the technology for water and/or wastewater systems. 

4.2.2 Acoustic Monitoring Systems 

Acoustic monitoring systems are installed along PCCP to provide continuous monitoring of the general 

condition of the pipe. PCCP has been used historically for large diameter force mains, and has been 

subject to failure due to internal or external corrosion. The systems work by detecting the acoustic signal 

produced by breaking or broken prestressed wire within pipes. While the systems do not identify 

individual defects, they are useful as screening techniques to determine if further condition assessment 

should be performed. There are currently two technologies available that provide continuous acoustic 

monitoring of PCCP. These products are described below. 

Acoustic Emission Testing (AET) – Pressure Pipe Inspection Company 

Acoustic Emission Testing (AET) is as an acoustic monitoring system used primarily to monitor the 

deterioration of PCCP water mains. It has also been used to evaluate sewage force mains. AET is based 

on the detection of the acoustic energy released when prestressed wire breaks or deflects. The system 

detects general distress in the pipeline by determining the frequency and number of wire breaks, or wire 

related events, over a period of time. The AET system determines the location of the wire related events 

based on the arrival time of the acoustic signals at a series of sensors within the pipe. Since the technique 

does not detect the number of broken wires, but rather general distress in a given section of pipeline, it is 

best used as a screening technique prior to utilizing other methods to pinpoint defects. 

The AET system is made up of a series of units located along the pipeline. Each unit contains a sensor 

(either a hydrophone or an accelerometer) and a signal processor, a base station, and a precision timing 

device. The hydrophones are inserted into the pipeline through taps at a spacing of approximately 500 to 

3,000 ft; spacing is largely dependent on pipeline diameter (smaller pipes require closer spacing than 

larger ones). The accelerometers are surface mounted; spacing is more flexible when this type of sensor 

is employed. The signal processor is a small mobile computer that is located close to the hydrophone. It 

monitors the signals detected by the hydrophone and transmits signals that indicate wire related events to 

the base station. The base station consists of a personal computer, a wireless communication module, and 

an internet communication module. The precision timing device, a GPS antenna and processor, provides 

location information on each sensor and determines the timing of acoustic events. 

AET can be used to monitor active distress in PCCP 18-in. or greater in diameter. The system works 

while pipelines are fully operational. The technique is valuable for providing advanced warning of pipe 

failure, and for screening pipe networks to determine which pipes are deteriorating. However, the 

technique cannot detect individual defects within a pipe. 

SoundPrint® - Pure Technologies 

SoundPrint® is a patented acoustic monitoring technology used to provide continuous, non-destructive 

remote monitoring of water and wastewater pipelines, storage tanks and other structures. Introduced in 

1993, the original version of SoundPrint® used hydrophones to detect breaks in prestressed wire in 

PCCP. The newer SoundPrint® AFO system, introduced in 2005, uses acoustic fiber-optic cable for 

detecting acoustic signals. 

Soundprint® AFO monitoring of PCCP involves the deployment of fiber-optic cable into the pipeline. 

The cable is inserted into pipelines through new valves installed in manholes. Because the entire fiberPage 4-33 
optic cable acts as a sensor, up to 12,000 ft of pipeline can be monitored from a single access point. The 

sensor does not contain any electronics, therefore there is little to no background noise created by the 

device. 

4.2.3 Sonar and Ultrasonic Testing 

Sonar, an acronym for Sound Navigation and Ranging, was developed in 1906, and is widely used for 

maritime use. The first use of sonar for inspection of pipelines was carried out by WRc in 1987. Sonar 

testing involves very high frequency ultrasonic sound waves that reflect off the material being inspected, 

allowing for the detection of defects. 

Sonar/ultrasonic inspections of pipelines are accomplished by passing a sonar head through the pipe being 

inspected. Depending on the size and flow conditions of a pipe, the sonar head is deployed into the 

pipeline on a raft, skid, or robotic tractor. As the sonar head moves through the pipeline, it sends out very 

high frequency ultrasonic signals, which are reflected by the pipe walls and then received by the sonar 

head. The reflection of the signals changes when there is a change in the material it is being reflected by, 

allowing for the detection of defects. The time between when the signal is sent and received can be used 

to determine the distance between the sonar head and the pipe wall, as well as to determine the internal 

profile of the pipe. 

Sonar inspection results in a detailed profile of the pipe wall below the water surface, which can be 

analyzed by a variety of methods. Sonar can detect pipe wall deflections, corrosion, pits, voids, and 

cracks. Sonar inspection can also detect and quantify debris, grease, and silt, and can distinguish between 

hard and soft debris; however, defects in the pipe wall can sometimes be obscured by grease and debris. 

According to Thomson et al. (2004), defects greater than 1/8 inch (3 mm) can be detected. This applies to 

pipe wall pitting and cracks as well as debris accumulation. Sonar does not require bypass pumping or 

pipe cleaning. Sonar inspection can be used in areas of poor visibility where it is difficult to use CCTV 

inspection. It is a versatile inspection method and can be used for inspecting gravity sewers and force 

mains. 

One drawback to sonar is that it can only be operated in air or in water, not in both simultaneously. In 

some cases, a sonar system is utilized with a CCTV system, so that inspection of pipes both above and 

below the waterline can be accomplished simultaneously. In order to overcome this limitation, research is 

being done into development of systems with separate transducers, one for use in air and one in water, so 

that inspection of partially filled pipes can be accomplished. Additionally, longitudinal cracks in pipes 

can be difficult to detect. 

Commercial sonar pipe inspection tools typically consist of an underwater scanning transducer, a sonar 

processor, and a color monitor. Table 4-9 highlights a selection of sonar-based pipe inspection products. 

Page 4-34 
Table 4-9: Sonar Product Comparison 

DEVICE: 

VENDOR 

SEWER TYPE/ 

PIPE SIZE 

DEFECTS 

DETECTED NOTES 

Amtec Sonar: 

Amtec Surveying, Ltd. 

Force mains 

>21 in. 

Deformations, holes, breaks, 

and pipe wall loss. 

A-SIS 

Aquacoustic 

>12 in. Pipe size & distortion, 

holes, debris, scour, erosion 

Combines sonar and 

CCTV 

Envirosight Gravity 

>4 in. 

Pipe diameter, shape 

capacity, corrosion, cracks, 

debris 

Attachment for CCTV 

PipeEye: 

PipeEye International 

Force mains, gravity 

>10 in. 

Build-up, deformities, flow 

restriction, water level 

RVS2: 

R&R Visual 

>10 in. Open cracks, debris, 

sediment 

Sonar Profiler System 

(submerged): CUES 

Force mains 

>12 in. 

Defects, blockage, debris 

Sonar Profiler System 

(semi-submerged): CUES 

>12 in. Defects, blockage, debris Combines sonar and 

CCTV 

Sonar Sewer Profiling 

Attachment: Redzone 

Force mains, gravity 

>36 in. 

Blockages, deformations, 

capacity, sediment 

Attachment for the 

Responder platform 

Sonar Sweep Attachment 

Redzone: 

Force mains, gravity 

>36 in. 

Blockages, deformations, 

capacity, sediment 

Attachment for the 

Responder platform 

TISCIT: 

Amtec Surveying, Ltd. 

Gravity 

>21 in. 

Deformations, holes, breaks, 

and pipe wall loss 

Combines sonar and 

CCTV 

Ultrascan CD: 

GE Oil & Gas 

Force mains, gravity Axial cracks 

Ultrascan DUO: 

GE Oil & Gas 

Force mains, gravity 

>24 in. 

Wall loss and cracks 

Ultrascan WM: 

GE Oil & Gas 

Force mains, gravity Wall loss 

Ultrasonic Inspection Robot 

Inspector Systems 

Force mains 

12 -20 in. 

Wall loss (measures wall 

thickness) 

Incorporates highresolution CCTV 

Wavemaker: 

Guided Ultrasonics 

Force mains, gravity 

>2 in. 

Wall loss Uses guided waves 

(Lamb wave), mounted 

to outer surface of pipe. 

4.3 Electrical and Electromagnetic Methods 

Several sewer evaluation techniques utilize electrical or electromagnetic currents. The electrical leak 

location method is used to detect leaks in surcharged non-ferrous pipes. Eddy current testing (ECT) and 

remote field eddy current (RFEC) technology identify defects in ferrous pipes. Magnetic flux leakage 

(MFL) inspection is widely used in the oil and gas industry to measure metal loss and detect cracks in 

ferrous pipelines. Table 4-10 summarizes these technologies. 

Page 4-35 
Table 4-10: Electrical and Electromagnetic Methods Summary 

SUMMARY ELECTRICAL LEAK 

LOCATION ECT/RFEC MFL 

Sewer type Force main, gravity 

sewers, service laterals 

Force main, gravity sewers, 

service laterals 

Force main, gravity sewers, 

service laterals 

Material Non-ferrous Ferrous Ferrous 

Pipe size >3-in. >2-in. 2-in. to 56-in. 

Defects detected Cracks, leaks Metal loss, cracks, leaks, 

broken wire, graphitization, 

wall thickness 

Metal loss, circumferential 

and longitudinal cracks 

Original application Leak potential in 

geomembrane liners 

Inspection of piping and 

tubing including boilers, heat 

exchangers, cast iron pipes, 

and gas pipelines. 

Petrochemical industry 

Status Commercially available 

for wastewater pipes 

Commercially available for 

wastewater pipes 

Commercially available, 

limited use in wastewater 

applications 

Advantages Available for service 

laterals 

Can be used on pipes of most 

diameters, can be used to 

locate a variety of defects. 

Extensive experience with 

method in the oil and gas 

sector 

Disadvantages Gravity pipes must be 

filled prior to inspection 

Limited to ferrous pipes, 

typically requires postprocessing of data by vendor. 

Has not been extensively 

used for assessment of 

sewer pipes. 

4.3.1 Electrical Leak Location Method 

The Electrical Leak Location Method was first developed in 1981 for the inspection of geomembrane 

liners. The method became commercially available in 1985, and is one of the most widely used 

techniques for detecting leaks in geomembrane liners. The technique involves placing an electrode on 

either side of the material being tested, and connecting voltage to each electrode. Because the material 

being tested is an electrical insulator, voltage only flows through holes in the material. The area of 

defects in the material has high current density, which can be detected by measuring electrical potential in 

the survey area. Although primarily used for geomembrane liner inspection, the technique is also 

applicable to pipe inspection. 

As this technology relies on the pipe material being an electrical insulator, it can only be used on nonferrous pipes. The technology is useful for inspecting force mains, service laterals, and smaller gravity 

lines. While it is possible to inspect larger diameter gravity lines, since the technology requires gravity 

lines to be surcharged, the time and effort required to fill larger pipes might make this inspection method 

infeasible. 

Although there are more than twenty commercial providers of electrical leak location services for 

integrity monitoring of geomembrane liners, the Focused Electrode Leak Location (FELL) is the only 

application developed specifically for detecting leaks in pipelines. FELL, also referred to as Electro-Scan 

technology, and was developed in Germany by Seba Dynatronic in 1999. GRW Engineers, Inc. has 

introduced the FELL system in the US. The FELL system identifies leak potential in non-conductive (i.e. 

non-ferrous) sanitary sewer mains, gravity lines, and service laterals using electrical continuity 

technology. The original application, FELL-41, was designed for use in force mains. A technique has 

been devised to allow for the inspection of gravity sewers by this method as well. The corporation later 

developed FELL-21 for inspection of service laterals. As of 2004, there were three electro-scan devices 

located in the United States, two of which are owned by GRW Engineering in Louisville, KY. 

Page 4-36 
FELL 41– Seba Dynatronic/Metrotech 

FELL, or Electro-Scan, inspection is accomplished by feeding a mobile electrode, called a sonde, through 

the pipe of interest. Simultaneously, a fixed surface electrode, usually a metal stake, is placed in the 

ground. Electrical current is generated by the sonde and flows through the water within the pipe, through 

the pipe wall and earth surrounding the pipe, and to the surface electrode. As water, earth, and the 

connecting cables have a low electrical resistance and the pipe material has a high electrical resistance, 

very little current flows between the two electrodes. However, if a leak exists in the pipe, the electrical 

current passes through it easily; the larger the defect, the greater the current that flows through. The 

electrical current flowing between the two electrodes is measured by the sonde; this data is then 

transmitted to a laptop computer, which records data and displays graphically the current flowing through 

the pipe. 

The technique only detects defects in surcharged portions of a pipe; to inspect the entire circumference of 

pipes that are typically not surcharged, such as gravity sewers, the pipe must first be prepared by 

completely filling it with water. Two techniques are used to fill pipes in preparation for FELL-41 

investigation. The first involves plugging the downstream manhole and then filling the pipe with enough 

water that the pipe is covered at the upstream manhole; this method can be quite time-consuming and may 

result in back-up of service laterals. The alternative method involves the use of a sliding pipe plug. The 

sonde is attached to the upstream side of the plug, which is manually pulled a short distance down the 

pipe. The upstream portion of the pipe is filled so that the sonde is submerged, and then the plug and 

attached sonde is pulled through the pipe, so that the entire pipe wall can be assessed. 

FELL-41 is suitable for inspecting force mains ranging from 6-in. to 60-in. in diameter. The system only 

works on non-conductive pipes and lined metallic pipes, and can only detect defects below the water line. 

Although gravity sewers can be manually filled to allow for a complete inspection; the process of 

surcharging large diameter pipes requires extensive time and preparation. The product can be used to 

detect leaks caused by radial and longitudinal cracks, as well as faulty joints. 

FELL 21 – Seba Dynatronic/Metrotech 

The FELL-21works on the same principle as FELL-41, but is designed for use in 3-in. to 6-in. diameter 

service laterals. Rather than being deployed through the pipeline via a haul line, this device is inserted via 

a cleanout and moved through the pipe with a push rod. Like FELL-41, the device can only be used for 

the inspection of non-conductive pipes or non-ferrous pipes. FELL-21 detects leaks caused by radial and 

longitudinal cracks, as well as faulty joints. 

4.3.2 Eddy Current Testing and Remote Field Eddy Current Technology 

ECT and RFEC technology involve the generation of electric currents and magnetic fields to investigate 

the condition of ferrous material. ECT pipe inspection involves the use of an alternating current magnetic 

coil to induce an electric current in conductive pipes. In turn, the electric current generates small 

magnetic fields or eddy currents in opposition to the coil’s magnetic field, which results in a change in the 

impedance of the coil. As the magnetic coil transverses the pipeline, the change in impedance is 

measured, allowing for the identification of defects. The effectiveness of ECT for pipeline inspection is 

limited by an electromagnetic phenomenon termed “skin effect”. The density of eddy currents decreases 

exponentially with depth. This limits the detection of defects to those located on the surface of the pipe 

nearest the magnetic coil, because defects located deeper within the pipeline cannot be measured. 

The RFEC method was developed to surmount the limitations of standard eddy current testing. This 

method can detect both internal and external defects in pipelines. RFEC involves the deployment of a 

probe consisting of multiple magnetic coils, an exciter coil and one or more detector coils, through the 

pipeline. As in standard eddy current testing, eddy currents are induced in the pipe wall. These direct 

Page 4-37 
currents quickly attenuate as they flow along the pipe wall towards the detector coil that is typically 

located approximately two pipe-diameters apart from the exciter. A second magnetic field passes from 

the exciter to the outside of the pipe and flows along the outer pipe wall, then back into the interior of the 

pipe to reach the detector. This remote field attenuates very slowly along the outer pipe wall, and is 

therefore much stronger then the direct field when it reaches the detector. Pipeline defects and pipe wall 

thickness affect the propagation of the magnetic fields along the pipe walls, thereby altering the signal 

received by the detector. This allows for the identification of pipeline defects. 

ECT and RFEC testing are primarily used to detect defects in ferrous pipe walls, such as pitting, 

corrosion, leaks and cracks. These testing methods can be used for the inspection of small-diameter 

pipes, in some cases as small as two inches in diameter, as well as very large diameter pipelines. 

ECT/RFEC can be used in empty, full, and partially full pipelines. Devices utilizing ECT and RFEC 

technology can be used to inspect force mains and gravity sewers. However, since most gravity sewers 

are not constructed of ferrous materials, the technology has limited use for this application. 

ECT and RFEC testing services for ferrous structures are available from a variety of vendors. Several 

commercial applications are specifically designed for the investigation of gas, water, and sewer pipelines. 

The following are descriptions of some of these applications; as these technologies use the same basic 

principal, the summaries focus primarily on the differences between the various applications. 

Broadband Electromagnetic Methodology (BEM) – Rock Solid Proprietary Limited (Pty. Ltd), 

Australia 

BEM was originally developed by Rock Solid Pty. Ltd for use in the Australian mineral exploration 

industry. The technology has since been modified for use in pipeline inspection, and has been used for 

this purpose in both the United States and Europe. Unlike other RFEC applications, BEM is frequency 

independent, allowing operation of the device to be modified based on the material being investigated and 

site conditions. This reduces the likelihood that the device will be affected by electromagnetic noise, 

which can occur with the use of other ECT/RFEC applications. 

BEM has primarily been used for condition assessment of water mains. The technology can only be used 

on ferrous pipes, but does work through thick coatings and linings. This technology can be used to detect 

a variety of pipe defects including cracks and anomalies in the pipe wall. Thomson et al. (2004) 

conducted field demonstrations of this method, and they state it is able to detect metal loss to 0.04 inch 

(1mm). BEM can also be used to measure wall thickness, quantify graphitization, and locate broken wires 

in PCCP. 

BEM pipeline inspection can either be accomplished internally or externally. Internal pipeline inspection 

generally requires the pipeline to be taken out of service and emptied prior to deployment of the BEM 

device. As an alternative, the BEM device can be waterproofed. Internal inspection of pipelines can be 

accomplished in large diameter pipes by either pulling or pushing the device through the pipeline. A 

robotic version of the application is available for smaller pipelines (less than 36-in. in diameter). Results 

of pipeline inspections using BEM cannot be analyzed on-site; rather, results must be post processed. 

Special software is used to create a topographic map of the pipeline which can then be analyzed to detect 

pipe defects. 

Hydroscope – Hydroscope, Inc. 

The Hydroscope was developed as a collaborative effort between Hydroscope, Canada and EPCOR Water 

Services (Edmonton, Canada’s privatized water utility). The application was first used in 1995 in Canada 

and became commercially available in the United States in 1996. However, the U.S. licensee for 

Hydroscope is currently in bankruptcy. Therefore, the technology may not be available in the U.S. 

Page 4-38 
Originally developed for inspection of waterlines, the technology has since been used for the inspection of 

sewer mains. 

The Hydroscope consists of a series of stainless steel modules embedded with circuitry, creating a flexible 

probe which can travel through pipelines. The probe is connected to a computer in a service vehicle by a 

tether and data cable. Data cannot be analyzed in the field; rather, data are analyzed at the Hydroscope 

Analysis Center with a proprietary software package called HYDA or the more advanced HYREL. 

Like all ECT/RFEC-based pipeline inspection applications, the Hydroscope can only be used in pipes 

composed of ferrous material. One advantage of the Hydroscope system is that it functions in both dry 

and submerged conditions. Probes are available for pipe diameters in the range of 6-in. to 15-in. The 

technology can detect pitting, corrosion, graphitization and wall thinning in pipes. 

See Snake Tool – Russell NDE Systems, Inc. 

Russell NDE System’s, Inc.’s See Snake is a small, flexible device which uses RFEC technology to detect 

corrosion and pitting in pipelines and to measure wall thickness and surface area. The tool can also detect 

areas of pipe under external stress such as movement of soil, poor support, rippling, bridging and denting. 

This technology is primarily intended for inspection of pipes before purchase or after construction to 

ensure pipeline integrity, and after a pipeline failure to determine if there are additional defects in the 

vicinity of the break. 

Unlike most RFEC devices, which pass signals through a data cable, signals from the See Snake are 

detected from above ground. This allows for tracking the tool as it passes through the pipeline. Another 

distinguishing feature of the See Snake is that data analysis can be performed on site during the 

inspection, unlike other technologies which require off-site analysis. 

The See Snake is primarily used in the oil and gas industry. Currently, the tool is only available for small 

pipes, ranging in size from 2-in. to 8-in. in diameter. Given the small size of the device, and its ability to 

be pushed through pipelines by liquid, the See Snake is potentially viable for inspection of force mains. 

P-Wave® - Pure Technologies 

Pure Technologies’ P-Wave3

 system generates an electromagnetic field and detects changes induced in 

the field by broken wires in PCCP. Results of P-Wave inspection include an estimate of the number of 

broken wires, as well as their location. The technology allows for the evaluation of a pipe’s current 

condition and the identification of distressed areas. The system is available for use in sewer pipes; 

however, the pipe must be empty to use the product. P-Wave inspection is often followed up with the use 

of an acoustic monitoring technology, such as Soundprint®, also available from Pure Technologies. 

Remote Field Eddy Current/Transformer Coupling (RFEC/TC) – Pressure Pipe Inspection Company 

Pressure Pipe Inspection Company’s patented RFEC/TC is specifically designed for use in pre-stressed 

concrete pipe, including embedded Concrete Pipe, lined cylinder pipe, and bar-wrapped pipe. Rather than 

detecting defects such as corrosion, pitting, and leaks, this technology is primarily used to detect and 

quantify broken wires within the concrete pipe to determine whether pipe segments need further 

monitoring, repair, or replacement. In this application, the electromagnetic field generated by the exciter 

is amplified by the pre-stressed wires within the pipe. Signals generated by broken wires can be 

differentiated from those generated by intact wires. 

RFEC/TC is effective for inspecting pipes 25-in. in diameter and larger. The largest pipe inspected to 

date is 252-in. In addition to broken wires, RFEC/TC can detect manholes, blow-offs, short pipe lengths, 

3

 P-Wave stands for Polar Wave 

Page 4-39 
cylinder thickness, cylinder composition, wire pitch, diameter and wraps (Pressure Pipe Inspection 

Company, n.d.). RFEC/TC can be used for the investigation of both force mains and gravity sewers. 

Emerging Technology 

Due to the versatility of RFEC testing for the inspection of pipelines, several institutions are working on 

the development of new applications. The Gas Technology Institute is currently developing a tool for the 

inspection of gas pipelines of a variety of diameters, including ones with valve and bore restrictions and 

tight bends. The Southwest Research Institute has recently developed an inspection technology for 6-in. 

to 8-in. diameter gas pipelines that couples an RFEC system to a robotic transport tool, the Explorer II, 

developed by Carnegie Mellon University’s Robotics Engineering Consortium. Monash University in 

Australia has developed a RFEC tool called TESTAU. This instrument provides an improvement to the 

quality of visual data over other RFEC tools. 

4.3.3 Magnetic Flux Leakage Detection 

MFL is a widely used inspection technique for oil and gas pipelines. The MFL technique was first 

developed in the 1920s and 30s for materials testing. The Tuboscope, which became commercially 

available in 1965, was the first tool specifically developed for pipeline inspection. 

MFL detection involves the placement of one or more magnets near a pipe wall, leading to the 

inducement of a direct current magnetic field in the pipe wall. The strength and direction of magnetic 

fields are represented by flux lines. When a magnet is near a conductive pipe wall, the majority of flux 

lines pass through the pipe wall. However, in areas of metal loss, less flux can be carried than the intact, 

full wall sections of pipe. This leads to leakage of flux from pipe areas which have undergone metal loss, 

as well as a change in the shape of the induced magnetic field. Flux leakage is detected by sensors; 

computer software is then used to determine the type and size of anomalies detected by the sensor. 

MFL devices consist of several systems packaged into a single tool. At a minimum, an MFL tool 

contains a magnetizing element, sensor, data recording, and power systems. MFL tools are usually 

categorized as single piece or segmented. Single piece MFL tools contain all system components in a 

single rigid tool while segmented tools consist of multiple pieces joined to one another with flexible 

connectors. 

Inspection of pipelines via MFL detection involves the deployment of an MFL device through the 

pipeline. As the device moves through the pipeline, usually pushed by the product flowing through the 

pipeline, the tool detects and records changes in magnetic flux. Traditional MFL devices, also called 

axial MFL, produce a magnetic field oriented along the axis of the pipe. More recently, circumferential 

MFL has been developed whereby the magnetic field is oriented around the pipe, allowing for better 

detection of axial defects such as cracks, seam weld defects, and groove corrosion. 

MFL inspection only works on conductive cast iron or steel pipelines. Most MFL applications are large, 

and therefore only suited to larger diameter pipelines; however, some commercial applications have been 

developed for use in smaller diameter pipelines. Although MFL is most commonly used to detect metal 

loss, the technique can detect a variety of pipeline anomalies, including circumferential and longitudinal 

cracks. Newer, advanced MFL tools are additionally capable of producing accurate measurements of pipe 

defects. 

Given the widespread use of MFL technology in the oil and gas industry, there are a variety of 

commercial MFL products available. However, the technology has yet to gain acceptance in condition 

assessment for wastewater collection systems. The majority of MFL tools operate on the basic principles 

outlined in the previous section. The primary distinction between them is whether they use axial or 

Page 4-40 
circumferential MFL, and the applicable diameter range. Table 4-11 provides basic specifications on 

available MFL tools. 

Table 4-11: MFL Product Comparison 

DEVICE VENDOR TYPE PIPE SIZE NOTE 

AES 19 Advanced Engineering 

Services 

Circumferential 3-in. to 12-in. 

AES ECAT Advanced Engineering 

Services 

Axial >12-in. Works externally 

Axial Flaw Detection 

(AFD) Tool 

Rosen Inspection Circumferential 6-in. to 56-in. 

Corrosion Detection 

Pig (CDP) 

Rosen Inspection Axial 6-in. to 56-in. 

CPIG Baker Hughes Axial 4-in. to 48-in. 

LINSCAN Lin Scan Axial 6-in. to 56-in. 

MagneScan GE Energy Axial 6-in. to 56-in. 

MAGPIE TDW Services, Inc. Axial 4-in. to 42-in. 

MFL Inspection Tool NGKS Axial 8-in. to 56-in. 

Pipesurvey MFL Pipesurvey 

International 

Axial Bidirectional 

TranScan GE Energy Circumferential 12-in. to 36-in. 

VECTRA BJ Services Company Circumferential Inertial navigation 

Vertiline /V-Line* Baker Hughes Axial 2-in. to 36-in. Bidirectional 

*According to Baker Hughes, the Vertiline/V-line system is applicable for use in sewer lines. 

4.4 Laser Profiling 

Laser profiling generates a profile of a pipe’s interior wall. The technique involves using a laser to create 

a line of light around the pipe wall. For this reason, it is also called the lightline method. The laser light 

highlights the shape of the sewer, allowing for the detection of changes to the pipe’s shape, which may be 

caused by deformation, corrosion, or siltation. Laser inspection can only be used to inspect dry portions 

of a pipe. To assess the entire internal surface of a pipeline requires the pipe to be taken out of service. 

Lasers are often used in combination with other inspection methods, most commonly CCTV and/or sonar. 

Table 4-12 provides a summary description of the laser profiling technology. 

Table 4-12: Laser Profiling Summary 

SUMMARY 

Sewer type Gravity sewers, force mains. 

Material Any 

Pipe size Product dependent 

Defects detected Deformations, siltation, corrosion, 

Original application Earlier use in large diameter tunnels and caverns 

Status Commercially available 

Advantages Provides better data quality then CCTV alone, can be used to create 3D 

models of pipelines. 

Disadvantages Can only detect defects above the water line. 

Specific examples of laser profiling technologies are presented in the following section. 

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Active 3D Laser Scanning – Redzone Robotics 

RedZone Robotics offers the Active 3D Laser Scanning Attachment for its Responder Robotic platform. 

This attachment creates a three dimensional model of the pipe, which allows for visualization of features 

not visible by CCTV inspection. The attachment can be used to assess pipes ranging from 48-in. to 100­

in. in diameter, and requires a minimum 24-in. diameter manhole for deployment. Inspections up to 

5,500-ft. are standard while specialized configurations enable custom inspections of up to 14,000-ft. 

Coolvision – Sima Environmental 

Coolvision is an attachment for traditional CCTV systems. The laser system results in reports which 

detail pipe grade and deflection. The system allows for the detection and measurement of cracks, as well 

as the measurement of sediment, water depth, and service locations. 

Laser Profiler – CUES 

CUES offers the Laser Profiler as an attachment to the CUES CCTV system. The attachment easily snaps 

on to the system, and allows for the creation of reports which include measurements of sewer defects. 

The attachment works by projecting a ring of light on the pipe’s surface. The light is recorded by the 

CCTV camera as the inspection is conducted. Software is used to analyze the laser ring and create a 3D 

digital profile of the pipe. This can be done either from live or recorded video. The profiler can be used 

to detect and measure pipe size, ovality and capacity, laterals, water levels, and off-set joints, as well as to 

collect survey data. The CUES laser attachment can be used to inspect pipes ranging from 6-in. to 72-in. 

in diameter. 

Laser Profiling Tool - Envirosight 

Envirosight provides a laser profiling tool which can be used with either the ROVVER or SuperVision 

crawlers and a CCTV camera. The device can detect corrosion, cracks, debris, pipe deformation, and 

incorrect installation of liner. The tool can be used individually, or in combination with a sonar profiler to 

inspect the pipe surface below the flow line. The tool can be used in pipes ranging from 4-in. to 160-in. 

in diameter. The tool is used with machine vision software, which uses data gathered from the CCTV 

video to create a variety of reports, statistical analyses, and 2D or 3D models of the pipe. 

Laser Profiler – R&R Visual 

R&R Visual offers the Laser Profiler for inspection of dry gravity sewers. The tool works on pipes 

ranging in sizes from 6-in. to 160-in. in diameter. The device allows for accurate pipeline measurement, 

measurement of sediment depth and volume. R&R Visual suggests utilizing this technology to assist in 

soliciting accurate price quotes for pipeline cleaning in order to create cost savings for the utility owner. 

The system works with R&R Visual proprietary software and Clearline software for 3D modeling. 

4.5 Flow Meters 

Flow meters (area-velocity meters) typically operate by direct measurement of depth and velocity. Flow 

is then calculated based on the continuity equation. Metering devices referred to as “depth-only” or 

“primary” metering devices calculate flow using weirs or flumes based on flow discharge relationship 

equations. These metering devices are limited for pipe reaches that do not surcharge. Other “velocityonly” metering devices function by measuring velocity in pipe sections that continually operate under full 

flow conditions. 

Page 4-42 
Communication with a flow meter can be achieved in the following manners: direct connection by laptop 

in the field, telephone land lines, wireless digital telephone or internet technology, or radio frequency 

networks. This includes communication through such technologies as general packet radio 

service/enhanced data rates for global evolution (GPRS/EDGE); code division multiple access (CDMA); 

mobile digital radio technology, including CDMA-1XRTT and CDMA-EVDO (evolution data 

optimized). Although most meter data are collected with laptops in the field, wireless communication is 

becoming the most popular method for new meters. Most wireless communication uses internet 

technology. A major distinction between the communication approaches is whether each meter is 

assigned a fixed internet protocol (IP) address or a floating IP address. The floating IP address is the 

easiest and least costly to deploy, but it also allows only one-way communication from the meter to the 

host. Communication with a fixed IP address occurs only when initiated by the meter. Fixed IP 

addresses allow the user to communicate with the meter for altering set up features, changing alarm setup 

features and downloading new software. Many wireless carriers do not offer fixed IP addresses. 

Real time communication is a very popular concept and is becoming widely used in wastewater treatment 

plants. Implementing real time communication in sewers is more difficult for two reasons. Most meters 

operate by battery and frequent communication uses more energy than data collection does. Energy use 

for communication is high both for operating a modem with land lines and operating the radio frequency 

equipment for wireless communication. Additionally, the term “real-time” in sewers is actually “near 

time”, because most meter measurements are in 5-minute or 15-minute collection frequencies, as many 

operators prefer lower collection frequencies to achieve longer battery life. Most metering technologies 

relying on wireless communication operate in a one-way mode from the meter to the host. This strategy 

is dictated primarily by the energy cost to “stay awake” for incoming communication. 

The traditional view of real time data is from a Supervisory Control and Data Acquisition (SCADA) 

perspective in which data are collected at a high frequency from many “dumb” sensors and a central 

computer sorts and archives the data. This approach works well for process control. An operator is 

alerted to problems by the use of “set points”, such as a drop in dissolved oxygen level below a specified 

concentration. This may trigger an alarm condition requiring an operator response. Real time data in 

sewers have less value because there rarely are controllable processes in sewers, except for pump stations 

and perhaps diversion gates. 

Software for collecting and reporting flow monitoring data has evolved along with improvements in 

communication protocols. Desk-top programs for analyzing flow data, performance monitoring, and 

project reporting are being replaced with web-based applications, which connect wirelessly to flow 

monitors. These software applications automate time-consuming tasks; making them more reliable and 

cost-effective than traditional software programs. Additionally, some of the programs incorporate GIS 

functionality, allowing users to integrate flow data with GIS models of the sewer system. 

4.6 Innovative Technologies 

Besides the range of commercially available technologies for evaluation of wastewater systems and other 

underground pipes, several other innovative technologies are currently under development. While the 

following technologies are not currently commercially available for condition assessment of wastewater 

systems, they may be feasible methods of sewer assessment in the future. 

4.6.1 Gamma-Gamma Logging 

Gamma-gamma logging is a technique used primarily to evaluate cast-in-place concrete pilings and for 

vertical borehole investigation in the mining and oil and gas industries. The technique involves the use of 

a gamma-gamma probe, which consists of a source of gamma radiation such as cesium-137 and one or 

Page 4-43 
more gamma detectors. The detectors are shielded from direct radiation by a heavy metal such as lead. 

The gamma-gamma probe emits photons which react to surrounding material based on density. The 

photons are backscattered by the surrounding material, and data are recorded as a density log. Inspection 

using this technique is accomplished by raising and lowering the probe within a PVC inspection tube that 

is inserted into the concrete piling or borehole. Results of the inspection yield information on the average 

bulk density of the concrete. Properly constructed structures will have a consistent density. The 

technique can also be used to locate voids. 

To date, gamma-gamma logging has not been used in pipeline inspection. However, researchers at 

Karlsruhe University in Germany performed laboratory tests that indicated a gamma-gamma probe could 

be used to locate lateral connections and locate and measure the size of cavities in the bedding 

surrounding a pipe. The technology may be applicable for evaluating the overall condition of concrete 

pipe or for detecting voids in bedding surrounding pipes. However, significant application issues would 

exist in terms of training requirements and the tracking of the nuclear materials. These issues are faced by 

the users of nuclear density gauges for soil compaction control. 

4.6.2 Ground Penetrating Radar 

The U.S. military originally developed ground penetrating radar (GPR) to locate underground tunnels and 

mines. GPR operates on the same principle as radar. A transmitting antenna emits high-frequency radio 

waves into the ground. The waves travel through the ground until they reach a material which has a 

different conductivity and dielectric constant than the earth. The signal is reflected and recorded by a 

separate receiving antenna. The amount of time it takes for the electromagnetic radio waves to be 

reflected by subsurface materials can be analyzed to determine the position and depth of features below 

the earth’s surface. 

There are a number of commercially available GPR systems. While some are designed to be used to 

locate underground utilities, none is significantly used at present for pipeline inspection. GPR systems 

that have been used to date in North America for internal pipe inspection could be considered more in the 

prototype stage than in commercial use. However, since GPR can detect underground voids, it is 

potentially useful for examination of pipe bedding. GPR can also potentially be used to locate leaks, 

since saturated soil slows radio waves, resulting in a GPR profile showing a pipe deeper then would be 

expected. Research into using GPR for sewer and bedding condition inspections is ongoing. Research 

has already been conducted on its use for small diameter sewer lines and brick sewers. 

4.6.3 Infrared Thermography 

Infrared thermography (IRT) involves the use of an infrared camera to measure the temperature 

differential across the surface of an object. Software can then be used to create an image displaying 

different temperatures as different colors. This allows for the detection of the surface expression of 

thermal conditions beneath the surface. In this regard, it is a potential method of detecting sewer defects 

such as leaks and voids, both of which can result in surface temperature variations when a sufficient 

internal/external temperature difference exists. 

Two basic methods of IRT are generally employed: passive IRT, which requires no external heat source; 

and active IRT, which requires the use of a heat source such as an infrared tube light. Research into the 

use of passive IRT to detect defects in and around subsurface pipelines has been conducted. The method 

has been demonstrated to be capable of detecting subsurface defects such as leaks, voids, and deteriorated 

insulation. Because the process is carried out from the surface, and the equipment used can scan a large 

area quickly, the technology can be an efficient method for detecting pipe defects. Active IRT has been 

proposed as a method for pipeline assessment, but has not yet been evaluated. 

Page 4-44 
4.6.4 Micro-Deflection 

Micro-deflection is a nondestructive technology used to evaluate brick, concrete, and clay structures. The 

method involves the use of a load to create slight deformation, termed a micro-deflection, in the test 

material. The change in position of the structure is measured, and a graph of load versus deflection is 

created. Structurally sound test materials would be expected to have a consistent load versus deflection 

graph, while deteriorated sections of the material would have a different value on the graph. 

Although not a widespread method of evaluating wastewater pipes, micro-deflection has been used to 

evaluate brick sewers. However, the usefulness of micro-deflection is limited, because the process can 

only give a general understanding of pipe condition, such as the integrity of joints, rather than identifying 

individual defects. In addition, plastics such as PVC and HDPE cannot be inspected using this method. 

4.6.5 Impact Echo/Spectral Analysis of Surface Waves (SASW) 

Impact Echo and SASW are two related techniques for evaluation of concrete and masonry. Both work 

by subjecting a pipe to an elastic impact, produced by a device such as a pneumatic hammer, which then 

propagates through the pipe. The waves are reflected by internal flaws, as well as the surface of the 

material, and the reflected waves are detected by an acoustic transducer such as a geophone located on the 

exterior of the pipe. The technique can locate and measure cracks, delaminations, voids, and 

honeycombing. 

Impact Echo testing services are provided by several companies and its applicability for pipelines has 

been researched. The Acoustic Impact Hammer, developed by the University of Karlsruhe in Germany, 

uses a hammer to tap the inner surface of a pipe; laboratory trials resulted in the detection of cracks and 

cavities around the pipe. A German technology which uses lasers to scan the response to impacts and 

analyze them via SASW is available for tunnels and large pipes; however, this system requires entry into 

the pipe and is therefore only suitable for very large pipes. 

4.6.6 Ultrasonic Testing Systems 

Several new ultrasonic-based testing systems are currently under development. Researchers at King’s 

College in London are developing a multi-sensor system termed the Ultrasonic-Based Inspection System 

that can be integrated into existing CCTV inspection systems. This system automatically classifies data 

based on an artificial neural network, and can detect very small cracks in the millimeter range. Research 

into use of ultrasonic pulse velocity for the evaluation of concrete is being carried out at the University of 

Waterloo in Canada. Researchers at Pennsylvania State University are working to develop a sensor using 

No-Contact Ultrasonic technology, which would be deployed into pipelines on a wheeled carriage. 

Page 4-45 
5.0 Technology Forum Summary 

5.1 Background 

A technology forum was held on September 11 and 12, 2008 in Edison, New Jersey to discuss the state of the 

science for condition assessment of wastewater collection systems and to identify critical gaps in current 

knowledge. The white paper was distributed to participants in advance of the meeting and served as a basis for 

forum discussions. The objective of the forum was to present the findings of the research and obtain direction for 

additional research and further evaluation during the field demonstration tasks. Figure 5-1 lists the presenters and 

attendees at the Technology Forum. 

WERF and other research institutions expressed interest in collaboration and sharing of research findings. WERF 

has completed twelve research projects related to condition assessment and rehabilitation of wastewater 

infrastructure in the last ten years; these research reports can be found at www.werf.org. WERF’s Condition 

Assessment Protocols project, completed in 2007, provides guidance on developing and implementing a condition 

assessment program, and includes an inventory of condition assessment tools and techniques. On-going WERF 

research includes development of decision support tools and implementation guidance for risk analysis, costbenefit, and estimation of residual life. Virginia Tech is working on a WERF project to create the National 

Database for Sustainable Water Infrastructure Management, with the objective of creating a web-based model that 

can be used by utilities to determine information requirements for asset management decisions and support the 

formal specification of data requirements. 

5.2 General Discussion 

The primary components of any asset management program include the identification, location and condition of 

assets; the determination of their useful life, and their valuation. Condition assessment provides the critical 

information needed to determine the condition of each pipe within the system and its estimated time to failure or 

remaining useful life. Critical gaps in the use of condition assessment as an asset management tool include lack 

of consistent, standard condition assessment protocols; methods for the systematic collection of data; and formal 

risk assessment methods to prioritize resources for maintenance and or/rehabilitation activities. 

Data needs for conducting condition assessment and making asset management decisions were discussed at the 

Forum. It is important to define data needs so resources are spent wisely. The level of data needed for day-to-day 

management is different than what is needed for making decisions on major rehabilitation. Some meeting 

participants suggested that simple rules of thumb are adequate for making rehabilitation decisions (i.e., three or 

more major defects per 250-300 foot pipe segment triggers rehab or replacement). It was agreed by the 

participants that very detailed information is needed for CMOM. Better data including historical information are 

required for modeling. There is a concern that creating large databases for condition assessment data would be 

overwhelming to utilities. There is added value from gathering extra data. Information from a variety of 

inspection tools should be used to make better decisions; CCTV is only one aspect of assessment and should not 

be used in isolation. 

Flow monitoring is an important tool in asset management. In one case, pipes were going to be replaced at 

tremendous cost, but flow monitoring data showed a restriction at a stream crossing was causing a backup; the 

restriction was fixed, and overflows were reduced dramatically at a much lower cost. Flow assessment data can 

be used to assess sewer condition and long-term system performance and to help calibrate models. Flow metering 

data is traditionally used to generate hydrographs which provide information about water upstream of the meter. 

Scattergraphs (displays of paired depth and velocity readings that look like a pipe curve under normal flow 

conditions), can reveal both upstream and downstream conditions, and can be used as verification of other 

inspection data. Flow metering data may not be useful for predicting pipe failure. 

The development and implementation of condition assessment programs was a topic of discussion. Most 

condition assessment programs are currently focused on identifying and correcting I/I problems. A question was 

raised as to whether condition assessment should focus on other sewer defects in the future. Some utilities focus 

on coding defects, but may not spend enough time on identifying and correcting problems. The condition 

Page 5-46 
assessment program should have a system-wide focus and not be limited to one aspect of the collection system 

such as laterals or manholes. 

An understanding of pipe failure mechanisms is needed to tailor a condition assessment program to the utility’s 

high priority needs and also to improve use of predictive models. The United Kingdom has developed a 

comprehensive database on wastewater utility assets and pipe failures that can be used to study pipe failure 

mechanisms. Pipe failure is dependent on many factors including the system design, installation, operation, 

maintenance and inspection. For example, system operating conditions (i.e. hydraulics, I/I) together with poor 

maintenance practices may cause accumulation of sediment and other debris, resulting in sewage blockages, 

overflows, increased hydrogen sulfide production and/or increased corrosion. The main cause of failure in ferrous 

force mains is internal corrosion whereas PCCP fails most often due to external corrosion. Rehabilitated pipe 

may fail at an accelerated rate depending on contractor experience, selection of rehab technology and the 

understanding of baseline conditions. Many failures can be traced to human error. 

There are many tools and risk assessment models for decision making related to asset management, ranging from 

simple to complex. A question was raised as to whether utilities should use simple vs. complex tools. A one-size 

fits all approach does not seem appropriate. One tool that is needed is a branched decision-making tree based on 

defect coding that can help prioritize areas for inspection. Decision making models are used to assess the 

probability of failure and the consequences of failure. With accurate assessments of the probability of failure and 

the consequences of failure, cost-effective decisions can be made on risk mitigation. While the physical science is 

good, the decision sciences are lagging. Utilities often lack the input data for pipe failure prediction models. 

There is a need for better decision making, and to improve on the general rules-of-thumb to make decision 

making more cost effective. 

A number of models related to risk-based pipe performance and condition assessment were presented and 

discussed at the Forum: 

•	 An on-going WERF project is developing a web-based model that can be used by utilities to 

determine information requirements for asset management decisions and support the formal 

specification of data requirements. The project is developing protocols and methods for predicting 

the remaining economic life of water and wastewater pipes, and developing a condition/performance 

index. 

•	 Fuzzy logic can be used for modeling pipe deterioration and to help make decisions on pipe renewal. 

Fuzzy mathematics provides an alternative in cases where pipe condition data are lacking. It analyzes 

possibilities rather than probabilities of failure. The method was applied to large water transmission 

mains as part of an AwwaRF project. Prototype software T-WARP is available on AwwaRF’s 

website (AwwaRF Project No. 2883). 

•	 CARE-S, funded by the European Union, was designed as a proactive approach to develop methods 

and software that support efficient rehabilitation decisions. Failure codes developed as part of this 

project have been adopted by six European countries to date. CARE-S can be used for failure 

forecasting, assessments of hydraulic performance and environmental impacts, and selection of 

rehabilitation technologies. 

•	 A simple approach for condition assessment presented at the Forum taps into the utility’s extensive 

knowledge of the piping network rather than a comprehensive database of pipe information. The 

approach uses the utility’s “beliefs” or observations about pipe condition to develop a criticality 

rating of likelihood and consequences of failure. The approach is user friendly and does not require 

expert input. It can be applied using a simple computer program by utilities and their consultants. 

The approach was developed by a WERF-funded project, SCRAPS. 

5.3 Critical Gaps Identified in State of the Science 

Critical gaps in our knowledge of inspection technologies, and our ability to diagnose and predict infrastructure 

failures were identified at the Technology Forum and are summarized below. 

1.	 Research is needed to further define the costs and benefits of pipe inspection and rehabilitation as part 

of a utility’s condition assessment program. Methods of determining the impact of deteriorating 

collection systems on municipal budgets are needed. 

Page 5-47 
2.	 Inspection technologies need to be identified for the following applications: 

a.	 Reduce use of confined space entry during sewer system inspections and investigations. 

b.	 Affordable inspection technology that utilizes multi-sensor devices on a small transportable 

package. 

c.	 Inspecting pipes below the waterline. 

d.	 Inspecting force mains that are in service. 

e.	 Inspecting laterals. 

3.	 Data management methods and models are available but a lack of standardization makes it difficult to 

compare historical data collected with different inspection technologies that have proprietary data 

structures. 

4.	 Research is needed to improve how asset condition is tracked over time. Geospatial information 

(with a high degree of accuracy) needs to be collected along with pipe condition data in order to link 

historical inspection data with an exact physical location. 

5.	 Information transfer to practitioners was identified as a critical industry need. Practitioners need 

training on topics such as infrastructure failure mechanisms; using historical inspection data for 

condition assessment applications; applying the PACP coding system to characterize pipe defects; 

developing a condition assessment program; and preparing accurate record drawings for new and 

rehabilitated pipe. Practitioners need simple condition assessment tools (i.e. scattergraphs for 

analyzing flow data, decision trees, and rules of thumb). 

5.4 Recommended Next Steps 

Based on the Technology Forum discussions and findings, the project team has identified the following 

technologies for possible inclusion in the project’s field demonstrations: 

1.	 Focused Electrode Leak Location System FELLS 41. 

2.	 Ultra-wide band (UWB). 

3.	 Laser (2D/3D). 

4.	 Autonomous crawler technology. 

5.	 Zoom Camera. 

6.	 Digital scanning vs. CCTV. 

7.	 Flow metering analysis as input to decision making tools to prioritize need for inspection. 

8.	 Embedded sensors to monitor deflection, corrosion potential, and pressure. 

Page 5-48 
PROJECT TEAM 

The Cadmus Group 

*Katherine Martel 

Ralph Jones 

Chi Ho Sham 

The Louis Berger Group

Lou Ragozzino 

*Christopher Feeney 

Samantha Hogan 

ADS

Pat Stevens 

Michael Bonomo 

RedZone Robotics 

*Scott Thayer 

Brian Bannon 

*John Fortin-Independent Consultant 

TECHNOLOGY EXPERTS 

*D. Thomas Iseley - Purdue University *Lucio Soibelman - Carnegie Mellon University 

Jeff Plymale – RJN Group *Raymond L. Sterling - Louisiana Tech 

*Dan Murray - USEPA ORD *Tony Urquhart – MWH Global 

*Roy Ramani – WERF *James Thomson - Consultant 

*Duncan Rose – GHD Consulting Inc. *Annie Vanrenterghem-Raven - NYU Polytechnic 

*Sunil K. Sinha - Virginia Tech *Zack Zhao - Ultraliner, Inc. 

US EPA PARTICIPANTS 

Steve Allbee *Dennis Lai Ari Selvakumar 

Richard Field *Dan Murray Anthony Tafuri 

Evelyn Huertas Michael Royer Carlos Villafañe 

STAKEHOLDERS 

Steve Allbee – USEPA Office of Water 

*Yehuda Kleiner – NRC Canada 

Troy Norris – ASCE Pipeline Division 

*Roy Ramani - Water Environment Research Foundation (WERF) 

*Rod Thornhill – National Association of Sewer Service Companies (NASSCO) 

Marty Umberg - National Association of Clean Water Agencies (NACWA) 

Robert A. Villee – WEF Collection System Committee 

ADDITIONAL ATTENDEES 

Wendy Condit – Battelle 

George Kurz - Barge Waggoner Sumner & Cannon 

Robert Pennington - Camp Dresser & McKee Inc. 

Lily Wang - Battelle 

Dan Watts - New Jersey Institute of Technology 

*Technology Forum Presenter 

Figure 5-1: Technology Forum Attendees 

Page 5-49 
6.0 References 

American Concrete Institute. (2000). Service-Life Prediction: State- of-the-Art Report. American 

Concrete Institute: Framington Hills, MI. 

American Water Works Association Research Foundation (AwwaRF). (2005). Risk Management of 

Large-Diameter Water Transmission Mains. AwwaRF Project No. 2883. AwwaRF: Denver, CO. 

Fleury, M.A. and Warner, J. (2007). Arizona’s Largest Condition Assessment. Proceedings of WEF 

Collection Systems Specialty Conference, May 13-16, Portland, OR. 

Marlow, D., Heart, S., Burn, S., Urquhart, A., Gould, S., Anderson, M., Cook, S., Ambrose, M., Madin, 

B., and Fitzgerald, A. (2007). Condition Assessment Strategies and Protocols for Water and 

Wastewater Utility Assets. Water Environment Research Foundation (WERF): Alexandria, VA and 

IWA Publishing: London, United Kingdom. 

McDonald, S.E. and Zhao, J.Q. 2001. Condition Assessment and Rehabilitation of Large Sewers. Report 

No. NRCC-44696. Institute for Research in Construction, National Research Council Canada: 

Ottawa, Canada 

Merrill, M.S., Lukas, A., Palmer, R.N., and Hahn, M.A. (2004). Development of a Tool to Prioritize 

Sewer Inspections. WERF: Alexandria, VA. 

National Association of Sewer Service Companies (NAASCO). (2001). Pipeline Assessment And 

Certificate Program (PACP),v. 3.0. NASSCO: Owings Mills, MD. 

Pressure Pipe Inspection Company, The. (n.d.). The Remote Field Eddy Current / Transformer Coupling 

Technology (RFEC/TC). Retrieved December 10, 2008 from 

http://www.ppic.com/home/download.html 

Rahman, S. and Vanier, D.J. (2004). Municipal Infrastructure Investment Planning. MIIP Report: An 

Evaluation of Condition Assessment Protocols for Sewer Management. Report No. B-5123.6, 

Institute for Research in Construction: Ottawa, Canada. 

Thomson, J.C. (2008). The Value of Inspection. Presented at: STREAMS Task Order 59 Condition 

Assessment of Collection Systems Technology Forum. Sept. 11-12, 2008. Edison, NJ. 

Thomson, J.C., Hayward, P., Hazelden, G. Morrison, R.S., Sangster, T., Williams, D.S., Kopchynkski, 

R.K. (2004). An Examination of Innovative Methods used in the Inspection of Wastewater Systems. 

WERF: Alexandria, VA and IWA Publishing: London, United Kingdom. 

U.S. Environmental Protection Agency (USEPA). (2002). Clean Water and Drinking Water 

Infrastructure Gap Analysis. Report No. USEPA-816-R-02-020, USEPA, Office of Water: 

Washington, District of Columbia. 

USEPA. (2005). Guide for Evaluating Capacity, Management, Operation, and Maintenance (CMOM) 

Programs at Sanitary Sewer Collection Systems. Report No. EPA-305-B-05-002, USEPA Office of 

Enforcement and Compliance Assurance: Washington, District of Columbia. 

Page 6-50 
USEPA. (2007). Innovation and Research for Water Infrastructure for the 21st Century Research Plan. 

Report No. EPA-ORD-NRMRL-CI-08-03-02, USEPA: Washington, District of Columbia. 

Water Research Centre (WRc). (2003). Manual of Sewer Condition Assessment, 4th edition. WRc: 

Swindon, Wiltshire, United Kingdom. 

Page 6-51 
Appendix A 

Technology Vendors
 

Page A-1 
Camera Technologies 

Digital Camera Inspection 

Product(s) Vendor/Address Phone/Fax/Email/URL 

DigiSewer Envirosight 

111 Canfield Ave. 

Randolph, NJ 07869 

Tel: (866) 936-8476 

Fax: (973) 252-1176 

Email: through website 

URL: http://www.envirosight.com 

Panoramo Rapidview-IBAK USA 

1828 West Olson Road 

Rochester, IN 46975 

Tel: (800) 656-4225 

Fax: (574) 224-5426 

Email: info@rapidview.com 

URL: http://www.rapidview.com 

Sewer Scanning 

Evaluation 

Technology (SSET) 

Hydromax USA, LLC 

1766 Brent Drive 

Newburgh, IN 47630 

Tel: (812) 925-3930 

Fax: (812) 925-3911 

Email: info@hydromaxusa.com 

URL: http://www.hydromaxusa.com 

Zoom Cameras 

Product Vendor/Address Phone/Fax/Email/URL 

AquaZoom Aquadata, Inc. 

95 5th Avenue 

Pincourt, Quebec 

Canada J7V 5K8 

Tel: (800) 567-9003 

Fax: (514) 425-3506 

Email: info@aquadata.com 

URL: http://www.aquadata.com 

Aries HC3000 Zoom Aries Industries Tel: (800) 234-7205 

Pole Camera 550 Elizabeth St. 

Waukesha, WI 53186 

Fax: (262) 896-7099 

Email: through website 

URL: http://www.ariesind.com 

Ca-Zoom PTZ GE Sensing & Inspection 

Technologies 

Tel: (888) 332-3848 

Fax: (866) 899-4184 

Quickview 721 Visions Drive 

Skaneateles, NY 13152 

Email: through website 

URL: 

http://www.geinspectiontechnologies.com 

CUES IMX Truck 

Mounted Zoom 

Camera 

CUES IMX Corporate Office 

3600 Rio Vista Ave. 

Orlando, FL 32805 

Tel: (800) 327-7791 

Fax: (407) 425-1569 

Email: salesinfo@cuesinc.com 

URL: http://www.cuesinc.com 

Page A-2 
PortaZoom CTZoom Technologies Tel: (888) 965-8987 

2500 Boul. Des Enteprises #104 

Terrebonne (Quebec) 

Canada J6X 4J8 

Fax: (450) 965-8987 

Email: info@ctzoom.com 

URL: http://www.ctzoom.com 

Push Cameras 

Product(s) Address Phone/Fax/Email/URL 

Insight Vision Push 

Camera 

Insight Vision 

600 Dekora Woods Boulevard 

Saukville, WI 53080 

Tel: (800) 488-8177 

Fax: (262) 268-9952 

URL: http://insightvisioncameras.com 

CrystalCam Push 

Camera 

Inuktun Services Ltd. 

2569 Kenworth Road, Ste. C 

Nanaimo, BC 

Canada, V9T 3M4 

Tel: (877) 468-5886 

Fax: (250) 729-8080 

Email: sales@inuktun.com 

URL: http://www.inuktun.com/headoffice.htm 

Flexiprobe Pearpoint/RADIODETECTION 

154 Portland Road 

Bridgton, ME 04000 

Tel: (877) 247-3797 

Fax: (207) 647-9495 

Email: rd.sales.us@spx.com 

URL: http://www.pearpoint.com 

Hydrus, Orion, 

Orion L 

Rapidview-IBAK USA 

1828 West Olson Road 

Rochester, IN 46975 

Tel: (800) 656-4225 

Fax: (574) 224-5426 

Email: info@rapidview.com 

URL: http://www.rapidview.com 

Lateral Launchers 

Product(s) Vendor/Address Phone/Fax/Email/URL 

LAMP CUES IMX Corporate Office 

3600 Rio Vista Ave. 

Orlando, FL 32805 

Tel: (800) 327-7791 

Fax: (407) 425-1569 

Email: salesinfo@cuesinc.com 

URL: www.cuesinc.com 

Lateral Evaluation 

Television System 

Aries Industries 

550 Elizabeth St. 

Waukesha, WI 53186 

Tel: (800) 234-7205 

Fax: (262) 896-7099 

URL: http://www.ariesind.com 

Lateral Inspection 

System 

RS Technical Services 

1327 Clegg St. 

Petaluma, CA 94954 

Tel: (800) 767-1974 

Fax: (707) 778-1974 

URL: http://www.rstechserv.com 

Page A-3 
IBAK LISY 150-M Rapidview-IBAK USA Tel: (800) 656-4225 

1828 West Olson Road 

Rochester, IN 46975 

Fax: (574) 224-5426 

Email: info@rapidview.com 

URL: http://www.rapidview.com 

Small Diameter Tractors 

Product(s) Address Phone/Fax/Email/URL 

ELKT100 Mini Pearpoint/RADIODETECTION 

154 Portland Road 

Bridgton, ME 04000 

Tel: (877) 247-3797 

Fax: (207) 647-9495 

Email: rd.sales.us@spx.com 

URL: http://www.pearpoint.com 

KRA 65 Rapidview-IBAK USA 

1828 West Olson Road 

Rochester, IN 46975 

Tel: (800) 656-4225 

Fax: (574) 224-5426 

Email: info@rapidview.com 

URL: http://www.rapidview.com 

Mighty Mini 

Transporter 

RS Technical Services 

1327 Clegg St. 

Petaluma, CA 94954 

Tel: (800) 767-1974 

Fax: (707) 778-1974 

URL: http://www.rstechserv.com 

Rovver 100 Envirosight 

111 Canfield Ave. 

Randolph, NJ 07869 

Tel: (866) 936-8476 

Fax: (973) 252-1176 

Email: through website 

URL: http://www.envirosight.com 

Versatrax 100 Inuktun Services Ltd. 

2569 Kenworth Road, Ste. C 

Nanaimo, BC 

Canada, V9T 3M4 

Tel: (877) 468-5886 

Fax: (250) 729-8080 

Email: sales@inuktun.com 

URL: http://www.inuktun.com/headoffice.htm 

Xpress Silver-Bullet 

Crawler 

Insight Vision 

600 Dekora Woods Boulevard 

Saukville, WI 53080 

Tel: (800) 488-8177 

Fax: (262) 268-9952 

URL: http://insightvisioncameras.com 

Long Range Tractors 

Product Vendor/Address Phone/Fax/Email/URL 

Versatrax 300 VLR Inuktun Services Ltd. 

2569 Kenworth Road, Ste. C 

Nanaimo, BC 

Canada, V9T 3M4 

Tel: (877) 468-5886 

Fax: (250) 729-8080 

Email: sales@inuktun.com 

URL: http://www.inuktun.com/headoffice.htm 

Page A-4 
Responder Redzone Robotics Fax: (412) 476-8981 

91 43rd St., Ste.250 Email: through website 

Pittsburgh, PA 15201 URL: http://www.redzone.com 

Acoustic Technologies 

In-Line Leak Detectors 

Product Address Phone/Fax/Email/URL 

LxSentry LxSix Photonics 

520 McCaffrey St. 

St-Laurent, Quebec 

Canada H4T 1N1 

Tel: (514) 599-5714 

Fax: (514) 599-5729 

Email: info@lxsix.com 

URL: http://www.lxsix.com 

Sahara Pressure Pipe Inspection 

Company 

1930 West Qual Avenue, Suite 

A 

Phenix, AZ 85027 

Tel: (866)-990-2466 

Email: info@ppic.com 

URL: http://www.ppic.com 

Smartball Pure Technologies 

Suite A, 9130 Red Branch Road 

Columbia, Maryland 21045 

Tel:1-800-537-2806 

Fax: (443) 766-7877 

Email: through website 

URL: http://www.puretechnologiesltd.com 

Acoustic Monitoring Systems 

Product Address Phone/Fax/Email/URL 

AET Pressure Pipe Inspection 

Company 

1930 West Qual Avenue, Suite 

A 

Phenix, AZ 85027 

Tel: (866)-990-2466 

Email: info@ppic.com 

URL: http://www.ppic.com 

Soundprint AFO Pure Technologies 

Suite A, 9130 Red Branch Road 

Columbia, Maryland 21045 

Tel:1-800-537-2806 

Fax: (443) 766-7877 

Email: through website 

URL: http://www.puretechnologiesltd.com 

Sonar/Ultrasonic 

Product Address Phone/Fax/Email/URL 

Amtec Sonar 

TISCIT 

Amtec Surveying Inc. 

3355 Lenox Rd. Ste. 750 

Atlanta, GA 30326 

Tel: (404) 504-7044 

Fax: (404) 504-7004 

Email: info@amtecsurveying.com 

URL: http://www.amtecsurveying.com 

Page A-5 
A-SIS AquaCoustic Remote Tel: (888) 3749-7601 

AquaCoustic Technologies, Inc. 

3339 West 8th Ave. 

Vancouver, BC 

V6R 1Y3 Canada 

Fax: (604) 730-8771 

Email: Info@AquaCoustic.com 

URL: http://www.aquacoustic.com 

Envirosight Envirosight 

111 Canfield Ave. 

Randolph, NJ 07869 

Tel: (866) 936-8476 

Fax: (973) 252-1176 

Email: through website 

URL: http://www.envirosight.com 

PipeEye PipeEye International 

Unit 28 – 6275 Harrison Dr., 

Park 2000 

Las Vegas, NV 89120 

Tel: (888) 756-2033 

Fax: (250) 753-2642 

Email: info@pipeeyeinternational.com 

URL: http://pipe-eye-int.com 

RVS2 R&R Visual, Inc. 

1828 West Olson Rd. 

Rochester, In 46975 

Tel: (800) 776-5653 

Fax: (574)-223-7953 

Email: support@seepipe.com 

URL: http://www.expipeinspection.com 

Sonar Profiler System CUES Corporate Office Tel: (800) 327-7791 

(submerged/semi­ 3600 Rio Vista Ave. Fax: (407) 425-1569 

submerged) Orlando, FL 32805 Email: salesinfo@cuesinc.com 

URL: www.cuesinc.com 

Sonar Sewer Profiling 

Attachment 

Sonar Sweep 

Attachment 

Redzone Robotics 

91 43rd St., Ste.250 

Pittsburgh, PA 15201 

Fax: (412) 476-8981 

Email – through website 

URL: http://www.redzone.com 

Ultrascan CD GE Inspection Technologies Tel: (866) 243-2638 

Ultrascan DUO 50 Industrial Park Road Fax: (717) 242-2606 

Ultrascan WM Lewistown, PA 17044 URL: 

http://www.geinspectiontecnologies.com 

Inspector Systems 

Ultrasonic Inspection 

Robot 

Aqua Drill International Inc. 

1300 FM 545 East 

Dickinson, TX 77539 

Tel: (281) 337-0900 

Fax: (281) 337-7270 

URL: http://www.inspector-systtems.com 

Wavemaker Guided Ultrasonics Ltd. 

30 Saville Road 

Chiswick, London 

W4 5HG 

United Kingdom 

Tel: +44 (0) 20 8991 3771 

Fax: +44 (0) 20 8987 0558 

Email: info@guided-ultrasonics.com 

URL: http://www.guided-ultrasonics.com 

Page A-6 
Electrical and Electromagnetic Products 

Electrical Leak Location Method 

Product Address Phone/Fax/Email/URL 

FELL-21 

FELL-41 

Metrotech Corporation 

3251 Olcott St. 

Santa Clara, CA 95054 

Tel: (800) 446-3392 

Fax: (408) 734-1415 

Email: sales@metrotech.com 

URL: http://www.fell21.com 

Eddy Current and Remote Field Eddy Current 

Product Vendor/Address Phone/Fax/Email/URL 

BEM Rock Solid Pty, Ltd. 

11 Evans Str. 

Burwood Vic 3124 

Australia 

Tel: (+613) 9335-6122 

Fax: (613) 9335-6733 

Email: info@rocksolidgroup.com.au 

URL: http://www.rocksolidgroup.com.au 

Hydroscope Hydroscope Canada, Inc 

8170 50 St. NW Suite 260 

Edmonton, AB, T6B 1E6 

Tel: (780)-450-6224 

Fax: (780) 450-6224 

Email: info@hydroscope.com 

URL: http://www.hydroscope.com 

See Snake Tool CHECK IF VENDOR 

Russel NDE Systems, Inc. 

4909 75th Avenue 

Edmonton, AB, Canada T6B 

2S3 

Tel: (780) 468-6800 

Fax: (780) 462-9378 

Email: info@russelltech.com 

URL: http://www.russeltech.com 

P-Wave Pure Technologies 

Suite A, 9130 Red Branch Road 

Columbia, Maryland 21045 

Tel:1-800-537-2806 

Fax: (443) 766-7877 

Email: through website 

URL: http://www.puretechnologiesltd.com 

RFEC/TC Pressure Pipe Investigation 

Company 

info@ppic.com 

http://www.ppic.com/home/index.asp 

Page A-7 
Magnetic Flux Leakage 

Product Address Phone/Fax/Email/URL 

AES 19 

AES ECAT 

Advanced Engineering 

Solutions, LTD 

South Nelson Road 

South Nelson Industrial Estate 

Cramlington, Northumberland 

NE23 1WF 

United Kingdom 

Tel: +41 41 618 0 300 

Fax: +41 41 618 0 319 

Email: info@roseninspection.net 

URL: http://www.aesengs.co.uk 

Axial Flaw Detection 

(AFD) 

Corrosion Detection 

Pig (CDP) 

Rosen Inspection 

Obere Spichermatt 14 

6370 Stans 

Switzerland 

Tel: +41 41 618 0 300 

Fax: +41 41 618 0 319 

Email: info@roseninspection.net 

URL: www.RosenInspection.net 

CPIG 

Vertiline/V-line, CPIG 

Baker Hughes 

12645 West Airport Blvd. 

Sugar Land, TX 77478 

Tel: (281) 276-5400 

Email: 

BPC_ebiz_USA@bakerpetrolite.com 

URL: http://www.bakerhughesdirect.com 

LINSCAN LIN SCAN 

205/206 

Al Zahra Shopping Complex 

U.A.E. 

Tel: +9716-7473600 

Fax: : +9716-7473800 

Email: Marketing@linscan.biz, 

URL: http://www.linscan.biz 

MagneScan 

TranScan 

GE Energy URL: 

http://www.gepower.com/contact/index.ht 

m 

MAGPIE TDW Services, Inc 

4220 World Houston Pkwy, 

Ste. 100 

Houston, Texas 77032 

Tel: (832) 448-7221 

Email: Chuck.Harris@tdwilliamson.com 

URL: http://www.magpiesystems.com 

MFL Inspection Tool NGKS 

7, Guilyarovsky St. 

Moscow, Russia 129090 

Tel: + 7 495 937 86 36/26 

Fax: + 7 495 937 86 35/31 

Email: khafizov@ngksint.com 

URL: http://www.ngksint.com 

Page A-8 
Pipesurvey MFL Pipesurvey International 

Schrijnwerkersstraat 13 

3334 KH Zwijndrecht 

P.O. BOX 117 

3330 AC Zwijndrecht 

the Netherlands 

Tel + 31 78 610 1428 

Fax + 31 78 610 2128 

Email: info@pipesurveyinternational.com 

URL: 

http://www.pipesurveyinternational.com 

VECTRA BJ Services Company 

414 Pinckney 

Houston, TX 77009 

Tel: (713) 224-1105 

Fax: (713) 229-0541 

URL: http://www.bjservices.com/ 

Laser Products 

Product Address Phone/Fax/Email/URL 

Active 3D Laser 

Scanning 

Redzone Robotics 

91 43rd St., Ste.250 

Pittsburgh, PA 15201 

Fax: (412) 476-8981 

Email: through website 

URL: http://www.redzone.com 

Coolvision Sima Environmental 

1153 E Ogden, # 705-135 

Naperville, IL 60563 

Phone: (630) 327-8503 

Email: sima@wideopenwest.com 

URL: http://www.simaenvironmental.com 

Laser Profiler CUES IMX Corporate Office 

3600 Rio Vista Ave. 

Orlando, FL 32805 

Tel: (800) 327-7791 

Fax: (407) 425-1569 

Email: salesinfo@cuesinc.com 

URL: http://www.cuesinc.com 

Laser Profiling Tool Envirosight 

111 Canfield Ave. 

Randolph, NJ 07869 

Tel: (866) 936-8476 

Fax: (973) 252-1176 

Email: through website 

URL: http://www.envirosight.com 

Laser Profiler R&R Visual, Inc. 

1828 West Olson Rd. 

Rochester, In 46975 

Tel: (800) 776-5653 

Fax: (574)-223-7953 

Email: support@seepipe.com 

URL: http://www.expipeinspection.com 

Page A-9