Sewer Condition and Blockage Detection Classification Using Novel Acoustic Instrumentation

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


In the UK, the sewer system is ageing, poorly monitored and around 300,000 km long. The system is subject to increasing capacity demands because of increased urbanisation, more stringent environmental regulation and the consequences of climate change in the form of more frequent and intense rainfall events. OFWAT, the economic regulator for the water industry, imposes a legal duty on water companies to maintain the structural and operational conditions of their sewer systems and also to progressively reduce flooding incidents from sewers. In 2004 OFWAT identified 5700 sewer flooding incidents and an additional 11600 properties with a 10% annual risk of flooding. In approximately 90% of these cases, flooding was caused by an obstruction in a section of sewer pipe. Consequently, monitoring pipes for obstructions and then rapidly removing them could form an important part of an effective programme to reduce sewer flooding. The aim of this project is to develop novel acoustic technology (sensor and software) to produce a near market prototype that can be used in a live sewer to measure rapidly and objectively in-pipe condition and identify blockages and damage. Sewer monitoring is currently limited to the interpretation of CCTV pictures or the use of LightLine surveys. These methods require a mobile trolley with camera to be inserted and travel up a pipe section acquiring images which are then manually examined and defects/obstructions classified according to the standard Sewer Rehabilitation Manual document. Discussions with sewer operators in the UK indicate that they CCTV survey around 2% of their networks every 5 years. This project will develop an alternative fast method for analysing objectively the condition of a sewer and locating blockages. Recent research at the University of Bradford (EPSRC grant EP/D058589/1) has proved that the area of pipe blockage, extent of cracks, water level and positions of lateral connections can be measured in the laboratory pipes using an acoustic method of inspection. In this way the pipe condition of a sewer could be determined between manholes in the airborne regime. The key element of this acoustic device is a small multi-sensor array and advanced, real-time signal processing algorithm which overcome the effects of ambient noise and reverberation in the manhole environment. The key barriers to transferring this technology to the commercial sector are: (i) construction of an intrinsically safe, robust instrument; (ii) acquisition of sufficient field data to demonstrate clearly to potential users that acoustic sensors can reliably identify defects and obstructions in sewers (iii) demonstration that the acoustic technology can provide data that is compatible with the conventional CCTV methods and can be mapped onto the existing sewer condition classifications and sewer databases used by UK water companies. The data collected in the field will be critical in determining the nature and extent of the industrial funding and commercial interest from potential stakeholders. The investigators are in contact with four commercial organisations who support this work: Richard Long Associates, Mouchel Parkman, Yorkshire Water Services and Thames Water. It is generally agreed that CCTV surveys take between 2 and 4 hours per 100m length for measurement with a similar time for image analysis. This costs between 2 and 40 per linear metre depending on the access constraints. Acoustic measurement potentially reduces the measurement and analysis time to tens of minutes per 100m. Significant efficiencies can be achieved. This would enable operators to survey more of their network more frequently so would allow for better monitoring strategies to be developed, the earlier identification of defects and especially blockages leading to fewer flooding incidents and better planned maintenance.


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Ali MT (2011) Rapid detection of sewer defects and blockages using acoustic-based instrumentation. in Water science and technology : a journal of the International Association on Water Pollution Research

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Banasiak R (2008) The reliability of sediment transport predictions in sewers: influence of hydraulic and morphological uncertainties. in Water science and technology : a journal of the International Association on Water Pollution Research

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Tolstoy A (2009) Detecting pipe changes via acoustic matched field processing in Applied Acoustics

Description The main aim of this project was to develop a portable, intrinsically safe acoustic instrument which is able to detect, locate and classify defects in underground pipes.
The main outcome of this project was an instrument prototype which comprises a portable PC, an electronic microcontroller module, cables, software and an acoustic sensor. This instrument was designed to work in aggressive sewer environments. It was tested at a range of sites in the UK and Europe.
Exploitation Route The basic research outcomes were published in journal and conference papers which are of use to researchers in the field. The technology which was developed as a result of this research is protected by patent applications which are exploited by the new spin-off, Acoustic Sensing Technology (
Sectors Construction,Electronics,Environment,Manufacturing, including Industrial Biotechology,Transport,Other

Description The output from the project was the hardware and software which were necessary to build and use the acoustic inspection equipment in practice. It the technology is being commercialised through the new spin-off company, Acoustic Sensing Technology (ASTL, who makes and sells the equipment to sewer survey companies and water utilities.
First Year Of Impact 2013
Sector Creative Economy,Electronics,Environment,Transport,Other
Impact Types Economic,Policy & public services

Title Improvements in and Relating to Apparatus for the Airborne Acoustic Inspection of Pipes 
Description This patent describes the use of acoustic intensity and new method of analysis of acoustical data which can be used to detect and classify changes in an underground pipe which is partially filled with fluid. 
IP Reference GB081519905 
Protection Patent application published
Year Protection Granted 2008
Licensed Yes
Impact A new spin-off company, Acoustic Sensing Technology Ltd ( was set up in February 2013 to manufacture and sell the equipment which implements the technology described in this patent application.
Description Attendance at 157th Meeting of the Acoustical Society of America in May 2009 
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 "Detecting and localizing pipe changes via matched field processing" was presented and peer review feedback was obtained.

I was subsequently invited by US EPA to carry out trials of this technology in the USA
Year(s) Of Engagement Activity 2009
Description Attendance at Novatech Conference in Lyon (France) 
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 This activity resulted in a much better understanding of the acoustic inspection technology which was developed through this research

The team was invited to carry out trials in Austria and Holland and to join INNOKANIS Project run by BOKU in Vienna (Austria)
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