Advanced numerical techniques for characterising obstructions in sewer pipes

Lead Research Organisation: University of Bradford
Department Name: Sch of Engineering Design and Technology

Abstract

The underground sewer system in the U.K. is approximately 300,000 km long, for which the replacement costs are estimated to be 104 billion. The sewer system is owned by the privatised water companies who have a legal duty to maintain the structural and operational conditions of their sewer systems, and this includes reducing flooding incidents. In approximately 80% of cases, flooding incidents are caused by obstructions arising from the deterioration of a pipe wall, or from large deposits of sediment and/or fat. The detection and removal of obstructions should form part of any maintenance programme, although the ability to do this is currently restricted by the lack of a fast and reliable method. This project will focus on using sound waves to detect and characterise obstructions in sewers. Here, loudspeakers generate a pressure pulse that travels down a sewer pipe; this pulse is normally strongly reflected by any obstruction it encounters and by using microphones to capture the reflected energy information about the obstruction may be captured quickly and easily. Accordingly, this method offers a fast and objective way to monitor large sewer systems.The proposed research aims to deliver a step change improvement to a prototype acoustic device developed in a previous (experimentally based) EPSRC project (EP/D058589/1). The current device relies on cross-correlation between new acoustic intensity measurements and measurements stored for known sewer defects; however, this methodology is limited by the number of experimental studies it's possible to undertake and difficulties when interpreting measured intensity data. Furthermore, the current method can say nothing about the geometry, or surface characteristics, of an obstruction, and there is no proof that a unique link exists between the measured data and the properties of the obstruction. The proposed research seeks to address these issues by using mathematical models to aid in the development of a new measurement methodology that treats the acoustic intensity as a complex quantity rather than using the traditional real valued representation adopted in the current device. Here, complex acoustic intensity has the potential to uncover significantly more information from scattered sound fields when compared to a real valued intensity representation, and it is the measurement of complex intensity in acoustic waveguides that forms the focus of this proposal.Although complex intensity measurements have the potential to deliver significantly more information, they are not well understood, especially for scattering from obstacles in an acoustic waveguides. Accordingly, to gain a better understanding of complex intensity it is desirable to develop mathematical models and here both frequency and time domain models are proposed. The frequency domain model is based on the finite element method in order to accommodate those irregular geometries typically found in sewer systems; the time domain model is based on taking an inverse Fourier transform of the frequency domain calculations and will also utilise an inverse analysis in order to address issues such as the uniqueness of measured data. Theoretical predictions will be compared with time-averaged and instantaneous complex intensity measurements obtained under laboratory conditions. In this way, a more general understanding of complex intensity will be developed before this knowledge is applied to the development of a new measurement methodology for sewer systems. Furthermore, to maintain relevance to real sewer systems problems known to affect the accuracy of field measurements, such as manholes, cracks, joints and pipe surface roughness will also be studied. Accordingly, the understanding developed with the mathematical models and laboratory measurements will be used to develop a new prototype experimental methodology suitable for reconstructing the geometry and surface characteristics of obstructions in real sewer systems.

Publications

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Duan W (2013) Measurement of complex acoustic intensity in an acoustic waveguide in The Journal of the Acoustical Society of America

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Kirill Horoshenkov (Author) (2012) Acoustic monitoring of water infrastructure

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Krynkin A (2013) An eigenvalue correction due to scattering by a rough wall of an acoustic waveguide. in The Journal of the Acoustical Society of America

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Romanova A (2012) Local head loss monitoring using acoustic instrumentation in partially full sewer pipes. in Water science and technology : a journal of the International Association on Water Pollution Research

 
Description The results of the experiments and numerical predictions show that the instantaneous acoustic intensity vector in a pipe is very sensitive to even small imperfections in the pipe geometry and wall material properties. Below the frequency of the first cross-sectional resonance in the pipe this quantity can be used to determine accurately the position and extend of a defect. Acoustic instruments, signal processing and pattern recognition methods have been developed as a part of this project.
Exploitation Route Water industry and sewer inspection companies. Acoustic Sensing Technology Ltd.
Sectors Electronics,Environment,Manufacturing, including Industrial Biotechology,Transport,Other

URL http://acousticsensing.co.uk/testimonials/
 
Description The findings have been used to understand better the capabilities and limitations of the acoustic reflectometry methods for detection of damage and blockages in underground pipes. These findings help to improve the quality of the SewerBatt technology which is now marketed by the University spin-off company, Acoustic Sensing Technology Ltd (http://www.acousticsensing.co.uk). The technology is now used by major UK water utilities. It is estimated that Thames Water alone has used SewerBatt to inspect over 6000 km of their pipe. Some of these findings were used to develop a new method to measure the acoustical and related non-acoustical properties of porous media including living plants.
First Year Of Impact 2013
Sector Electronics,Environment,Transport,Other
Impact Types Economic

 
Description Yorkshire Water Services (YWS) and other water companies accepted the new acoustic technology as an alternative to the existing inspection technologies which are based on CCTV
Geographic Reach National 
Policy Influence Type Citation in other policy documents
Impact The new acoustic inspection technology (SewerBAtt) is an innovative tool that YWS are using to survey sewer asset condition. It started out as a YW research project between Yorkshire Water's Innovation Delivery Team and The University of Bradford and it is now in commercial use worldwide. The acoustic sensor is inserted into a manhole and a sound wave is emitted for around ten seconds. The acoustic response of the pipe is then recorded and analysed to produce a "signature" for the pipe. The analysis is quick and gives an immediate indication of defect type and its location. The main practical advantage of this method over traditional inspection methods, such as CCTV, is the speed of measurement and the ability to measure from the manhole only. Acoustic surveys can be carried out by a single operator as the equipment is lightweight and no man entry is ever required. YWS are currently have 30 teams of surveyors proactively inspecting our sewers to locate defects and blockages that may lead to property flooding. YWS have equipped 6 of these teams with a SewerBatt each to enable them to survey more of the network at a quicker rate.
URL http://www.yorkshirewater.com/about-us/innovation.aspx
 
Description A Feasibility Study into the Use of Fibre Optic Cables for Condition Monitoring of Sewers
Amount £64,850 (GBP)
Organisation Moormead Solutions Ltd. 
Sector Private
Country United Kingdom
Start 01/2015 
End 12/2015
 
Description EPSRC DTA Studentship at the University of Bradford
Amount £75,000 (GBP)
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Academic/University
Country United Kingdom
Start 01/2005 
End 03/2008
 
Description Pervasive Sensing for Buried Pipes
Amount £7,290,965 (GBP)
Funding ID EP/S016813/1 
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Academic/University
Country United Kingdom
Start 03/2019 
End 02/2024
 
Description ASTL 
Organisation Acoustic Sensing Technology Ltd
Country United Kingdom 
Sector Private 
PI Contribution The research funded by the EPSRC EP/H015469/1 project help to improve the SewerBatt technology which was at that time being exploited commercially by Acoustic Sensing Technology.
Collaborator Contribution The company has provided field data against which new numerical models and instrumentation could be tested.
Impact A working acoustic instrument which is now marketed by Acoustic Sensing Technology Ltd. The research fellow who worked on this project, Dr. Tareq Bin Ali, is now employed by the company.
Start Year 2013
 
Title Pipe Inspection System and Related Methods 
Description This patent application relates to the new acoustic method for condition classification of defects in sewer pipes. 
IP Reference US61813792 
Protection Patent application published
Year Protection Granted 2013
Licensed Yes
Impact This patent application enabled the new Spin-off company, Acoustic Sensing Technology Ltd (http://www.acousticsensing.co.uk) to develop software which is able to classify conditions such as defects and blockages in sewer pipes based on the recorded acoustical signatures.
 
Title ScanField 
Description This software is designed to work as a part of the SewerBatt acoustic sensing technology or independently with data files saved in the standardised format. It is capable of detecting, locating and classifying the conditions in underground pipes. 
Type Of Technology Software 
Year Produced 2013 
Impact Important benefits of new technology are the cost and its ability to survey a larger proportion of the asset stock in much shorter time than when CCTV is used alone. This technology is not intended to replace CCTV completely, but it enables the operators to reduce the survey costs and increase the efficiency and levels of customer service by focusing CCTV on those pipes where need is greatest and managing interventions through measuring objective change. SewerBattTM can also be used to confirm that interventions such as pipe replacement, rehabilitation or cleaning have been carried out to a satisfactory standard. A report commissioning from an independent consultant found that potential savings in the inspection costs from the application of SewerBattTM technology ranging from 35% to 82% could be achieved. These savings enable more focused CCTV inspection to be carried out on a given length of sewer network or permit surveys of larger pipe lengths a given inspection budget. 
URL http://www.acousticsensing.co.uk/
 
Title SewerBatt instrumentation 
Description This product is designed to inspect rapidly the conditions in underground pipes using sound waves. It is marketed by the University spin-off company, Acoustic Sensing Technology Ltd. 
Type Of Technology Detection Devices 
Year Produced 2013 
Impact Important benefits of new technology are the cost and its ability to survey a larger proportion of the asset stock in much shorter time than when CCTV is used alone. This technology is not intended to replace CCTV completely, but it enables the operators to reduce the survey costs and increase the efficiency and levels of customer service by focusing CCTV on those pipes where need is greatest and managing interventions through measuring objective change. SewerBattTM can also be used to confirm that interventions such as pipe replacement, rehabilitation or cleaning have been carried out to a satisfactory standard. A report commissioning from an independent consultant found that potential savings in the inspection costs from the application of SewerBattTM technology ranging from 35% to 82% could be achieved. These savings enable more focused CCTV inspection to be carried out on a given length of sewer network or permit surveys of larger pipe lengths a given inspection budget. 
URL http://www.acousticsensing.co.uk/
 
Company Name Acoustic Sensing Technology UK Ltd 
Description Acoustic Sensing Technology (UK) Ltd was created in 2013, as a new Company, with investment from the North West Fund managed by 350 Investment Partners to provide new technology for the water industry and for other industries, both in the UK and worldwide. It is tasked with the manufacturing and sales of the new acoustic technology, SewerBatt, which was developed at the University of Bradford to inspect rapidly the conditions in underground pipes. 
Year Established 2013 
Impact Employment, delivery of new, more efficient technology and innovation solutions to water industry. Development of new instruments for underground asset inspection.
Website http://www.acousticsensing.co.uk/
 
Description Attendance at Yorkshire Water Services (YWS) Innovation event 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? Yes
Geographic Reach Regional
Primary Audience Professional Practitioners
Results and Impact YWS decided to invest in the development of two acoustic technologies: acoustic inspection of underground pipes; (ii) acoustic flow metering.
Year(s) Of Engagement Activity 2011
 
Description Attendance at the 6th International Conference on Sewer Processes and Networks 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact The paper entitled "Hydraulic head loss monitoring and determination of roughness by acoustic instrumentation in a partially full sewer pipe" was presented and generated discussion and paved the foundation for more work in this area.

A research grant from Sydney Water to test the acoustic inspection technology
Year(s) Of Engagement Activity 2010
 
Description Attendance at the Forum Acusticum Conference in Aalborg (Denmark) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Other academic audiences (collaborators, peers etc.)
Results and Impact A paper entitled "On the variation of the acoustic intensity vector near an open end of a pipe" was presented and this work received a valuable feedback.

Better understanding of the limitations and capabilities of acoustic intensity technology for pipe inspection
Year(s) Of Engagement Activity 2011
 
Description Attendance at the International Congress on Acoustics in Sydney (Australia) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Other academic audiences (collaborators, peers etc.)
Results and Impact The paper entitled "A method to calculate the acoustic intensity near an open end of a flanged round pipe" which generated discussion and set the agenda for the follow-up work

Development of the new measurement method based on acoustic intensity
Year(s) Of Engagement Activity 2010
 
Description Presentation at Connect Yorkshire Investment Forum to secure funding for SewerBatt technology 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? Yes
Geographic Reach National
Primary Audience Professional Practitioners
Results and Impact A former MP, Mr. Nick Hawkins, was engaged in the commercialisation work and helped to secure funding for the spin-off.

The notable impact was the funding from The North West Fund for Energy & Environmental to form Acoustic Sensing Technology Ltd.
Year(s) Of Engagement Activity 2012
 
Description Visit and presentation to Environmental Protection Agency of the USA 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact This was the invited visit and presentation to make the Agency aware of the capabilities of the new acoustic technology for the inspection of underground pipes.

The Agency have agreed to carry out trials of this technology and benchmark it against other pipe inspection technologies which are established or emerging.
Year(s) Of Engagement Activity 2012
URL http://cfpub.epa.gov/si/si_public_record_Report.cfm?dirEntryId=270690&CFID=13659741&CFTOKEN=38853203...