Water loss detectives

Water loss detectives

Water detectives
Water detectives diary wants to be a dedicated profile publication for all those interested in water loss detection. Each water loss team detection has a diary to register defects that has been found, identified noises and the most important the problems they faced.
Water loss detection activity was compare with an Indian listening the earth, with a doctor listening the water network pulse but also with a detective investigating water loss out of network---in antique Rome they were known as water commissaries .
All persons involved in systematic water loss detection must be well trained so the team can reach maximum efficiency in water loss detection.
This publication wants to offer to all are interested in the topic information related to water loss detection processes, news, studies, theories, equipment presentation, field experience and other articles dedicated to this topic.
This project is a follow up of the project launched in 2010 when the forum www.pierderiapa.forumgratuit.ro. This forum was created to present problems and solutions that are met in water loss detection activity and also to become a way of experience change between water operators .
As much as we share from our experience the best for the ones that cares! This way I would like to keep a vivid dialog, to be informed all the time and be open when listening other points of view. Learn others and from others instead of being in competition ! Each debate is a winning – SO BE A WINNER !
Thank you to all that sent articles for this edition and I invite you to make improvement proposals for the next editions.
I accept your critics and your suggestions and I hope you will find at least one useful article.
Enjoy your reading .

Alin Anchidin

Leak localization using the Cross-Correlation method. General presentation.


In time, detection and localization methods for noise sources within pipe systems have evolved, becoming more accurate.
Acoustic localization devices are the most popular. Whether we talk about noise and vibrations correlators or listening devices, acoustic detection methods are extremely widespread. For many companies which provide water services, these methods are the main tool for preventive maintenance. The leak detection procedures may include a “listening” stage using specialized microphones or aqua-phones. This type of localization depends on the knowledge of the user. The next stage is often called “precise localization” and involves the use of noise and vibrations correlators.
Along different acoustic localization procedures, one can find in the specialized literature detection methods which are based on: the use of colored gases, vapors monitoring, radars and sonars, pipe pressure monitoring, the use of fiber optics, the use of HTV closed circuit systems or thermographs.
For a better understanding of acoustic devices functionality we will shortly present the principle of acoustic leak detection in water pipes systems.
The flow of liquid out of the pipe, trough a leak point, causes specific sounds. These sounds travel in the pipe material, in the surrounding environment and in the liquid which is inside the pipe. The characteristics of these noises are affected by many factors. Their spectral components modify as the sound moves further from the leak point. Such sounds are called “leak noises”.
When using noise correlators, piezo-electrical sensors which come in contact with the pipe material acquire the generated leak noises. These noises are transmitted to a correlator. Because the leak noise wave travels with the same velocity in the entire pipe material, the sensor which is closest to the leak will be the first to acquire signal. Basically, the leak noise will first reach the closest sensor. The propagation velocity depends on the pipe material. If the speed value is known, either from literature or can be experimentally determined, the time difference of arrival (TDOA) from the noise source to the sensors indicates the position. Modern equipments include filters and amplifiers which help emphasize the leak signals characteristics and reduce the unwanted interferences.
The correlator operation principle is presented in Fig. 1. Transmission of recorded signals from the sensors to the correlator is implemented using radio waves. Mathematical relations are presented as a principle.


Fig. 1. The principle of noise source localization trough Cross-Correlation.

The Cross-Correlation is a fundamental method when we deal with signal processing algorithms for noise sources position identification (leak detection, in a particular case). The Cross-Correlation Function (CCF) indicates the degree with which two data sets are similar. It represents an important means of statistical analysis.
The CCF method refers to the relation between a recorded signal and a delayed version of the same signal. Trough the index of its maximum value, the CCF allows the calculation of the TDOA.
If we consider that x(n) and y(n) are two signals which travel from the noise source towards two piezo-electrical sensors (these signals contain N samples are considered stationary with zero mean values), we define the CCF as:

(1)

The index l is considered the time shift (time lag). The order of the estimator indices shows that the x(n) signal is not modified, while y(n) is shifted with l time units. Considering relation (1), a positive time lag indicates that the sensor which provides y(n) is further from the noise source. The sensor which provides x(n) is closer to the noise source. Basically, y(n) is a l time units delayed version of x(n). In order to obtain the normalized CCF (with values in the -1:1 interval) we can use relation (2). The scaling will not change the shape of the CCF.

(2)

For the special case when the leak is located exactly in the middle of the distance between the sensors, the CCF maximum value index is 0.
If the index of the CCF maximum value is r samples, one can calculate the TDOA value expressed in time units. It is Dtime = r∙Te , where Te is the sampling frequency value.


Fig. 2. Recorded leak signals. Fig. 3. Calculated CCF.

References:

1. O. Hunaidi, Wing T. Chu, Acoustical characteristics of leak signals in plastic water distribution pipes, Applied Acoustics, Volume 58, Issue 3, Pp.235-254, November, 1999.
2. S. Gokhale , J.A. Graham, A new development in locating leaks in sanitary sewers, Tunnelling and Underground Space Technology, August, 2003.
3. R. Pilcher, S. Hamilton, H. Chapman, D. Field, B. Ristovski, S. Stapely, Leak Location & Repair Guidance Notes, International Water Association, Version 1, March, 2007.
4. J.S. Bendat, A.G. Pirsol, Engineering applications of correlation and spectral analysis, John Wiley & Sons, Inc., Canada, 1980.
5. A. Papoulis, Probability, Random Variables and Stochastic Processes, McGraw-Hill, Inc., New York, 1991.
6. J. G. Proakis, D. G. Manolakis, Digital Signal Processing. Principles, Algorithms and Applications”, 4th Edition, Pearson Education Inc., Prentice Hall, USA, New Jersey, 2007.

Dr.ing. Raul Ciprian IONEL
“Politehnica” University from Timişoara
The Faculty of Electronics and Telecommunications

This work was partially supported by the strategic grant POSDRU/89/1.5/S/57649, Project ID 57649 (PERFORM-ERA), co-financed by the European Social Fund – Investing in People, within the Sectoral Operational Programme Human Resources Development 2007 – 2013.

water loss detectives

INTRODUCTION
Historical aspects

Water loss in distribution systems was important since antiquity.
An American science man opinion was that the Queen of Sheba could stop the fall of her empire if she would accorded more attention and invested more money in the existing water distribution and irrigation system. In antic Rome, as part of water culture, a great attention was accorded to water system maintenance. Aqueduct administrator surveyed water springs, basins and conduits with 700 people designated for this activity. As described most of the time they detected hidden leaks using hard would steaks to detect noise of the water loss.
Sextus Julius Frontinus (ca. 40–103 AD) was one of the most distinguished Roman aristocrats of the late 1st century AD, but is best known as an author of technical treatises, especially one dealing with the aqueducts of Rome- De Aquis Urbis Romae or De Aqueductibus In 95 he was appointed Water Commissioner of the aqueducts (curator aquarum) at Rome by the emperor Nerva, his work presents a history and description of the water-supply of Rome, including the laws relating to its use and maintenance, the first official report of an investigation about engineering works ever to have been published. In this report explains how he prepared maps of the system so that he could assess their condition before undertaking their maintenance. He says that many had been neglected and were not working at their full capacity. He was especially concerned by diversion of the supply by unscrupulous farmers and tradesmen using illegal connections. He therefore made a meticulous survey of the intake and the supply of each line, and then investigated the discrepancies. He made a meticulous overview of water supply and than studied the apparent anomalies. His evaluation was based on conduit or tub section and did not considered water velocity.
In UK Margaret Thatcher - Iron Lady in the 90`s privatised the water companies and the company that won the distribution had the main objective to decrees the water loss, established by OFWAT regulating authority. District meetings were organised to inform the people about the importance of useless water consumption and water loss. That was the time when water detectors or so called `loss inspectors` appeared, they made regular inspections at consumers connections and taps listening with a metal rod the noise of a water damage. This operation is based on the fact that any water loss make a noise that indicates a damage.
To locate the water loss it is used the noise produced by the water that bursts with pressure throw the break. The water generate acoustic waves and are cared away by water and pipes wall in both directions. The essential condition for water loss detection is the water pipe material to be able to transmit vibration. For metal pipes in normal conditions there are no problems. Contrary non metallic pipes are inert to sounds and very week sound transmitters. The sound are weaker farther we go from the source.At a moment it reaches the point that the sound waves in the water did not touch the material and practically the water loss noise is undetectable. Other factors with influence or interfere with the noise produced by the water flow are soil quality and density, the depth and and material of the pipe, water pressure, traffic, wind or water usage noise. This are the reasons for not be possible to predict the distance of the detectable noise of a leak.



Eng. Alin Anchidin
Water loss detection departament
SC AQUATIM SA Timişoara
România

The importance of valve operation

The main condition for a proper functioning of the network is valves functioning (gate valves, hydrants, main valves, emptied valves).
In case of failure on the network if a faulty valve closing, more consumers are affected, increase uptime, so the amount of water is lost and the damage increase itself.
If the valves separating areas of complete closure pressure is very important because leaks can cause serious problems in the operation system and lead to energy losses. In the areas with low pressure may cause problems due to increased pressure on internal and external network.
To make measurements in both the loss detection when measured night flows and fault location using acoustic correlator or any other method is necessary that the operating state of the valves to be perfect.
If increased flow is constant means a failure occurs. The evaluation results should be taken into account the possibility of a new consumer of such a new plant or irrigation system. The location of the leaks involves a series
of new measurements. Results can be checked after a fault correction.
If the area is too large, the system will not signal the emergence smallest leaks.
Correlator will indicate where the leak is or locate the damaged valve. The sound produced by the damaged valve is usually stronger than the fragment.
Flow measurements can not be performed if the valve does not close perfectly measuring point and valve defects involves dividing the measured sections. The valve malfunction makes it impossible to conduct zoning measurement.
Analysis of water losses is based on detection of "zero consumption" - or minimum consumption. The flow of water that flows through that portion of consumption in network provides real information only if the valves are fully closed.

Eng.Leila Kajnak
Head of Water loss detection departament
Aquaserv Tg. Mures

First romanian competition on water loss detection organized on
Mr. Vasile Ciomos’s proposal on
September 28-30, 2008



Satu Mare had the honor to be first romanian city that hosted water loss detection competition. How did it happed?
I was in Sibiu, attending a water loss detection workshop held by Andy Bowden, England, when together with the President of ARA, Ciomos Vasile, we started this project that seems to have had a great success, being probably the only project in Europe on this topic.
Mr. Ciomos, always receptive to new ideas, proposed the organization of this contest in Satu Mare under his direct sponsoring, attending every edition.
Mr. Andy Bowded was excited by this proposal, honoring us with his presence in the jury together with:

dl. Prof. MĂNESCU ALEXANDRU preşedinte CPPDA
ANDY BOWDEN consultat FOPIP I din England -UK
RICHARD NOAKES consultant FOPIP II din England- UK

Considering that no one has dealt with such a competition before, we were afraid of not getting fit in time to travel to the three proposed defects, reason for which the first edition had a small number of crews: 6 crews at the beginning and finally other three crews joined, the winner team from Timisoara was part of this last wave.

Important companies have participated like:

S.C. Compania Aquaserv Mureş
S.C. Compania de apă Someş S.A. Cluj
S.C Apa Nova S.A. Bucureşti
S.C. Apa-Canal Sibiu
S.C. Aquatim S.A. Timişoara
S.C. Apa-Canal 2000 S.A. Argeş
Apa Vital Iaşi
Compania de apă Braşov
Apa Buzău

The contest was developed in two workshops:
1. - practical test for detecting three burglaries
2. - presenting the strategies for loss reduction

The last day of the competition was focused on discussions with the manufacturer of the detection equipment and the presentation of technologies and equipments in this field.
There was a real burglary and a nonexistent one (in order to test the vigilance of the competitors) and an error due to a thermal channel.
The presentations of the strategies were special, each member team having the possibility to learn something one from the other.
As observers at this competition have participated some representatives of companies that wanted to acquire auto-laboratory and to make their own strategies.
We are sure that all the participants were winners both literally and figuratively leaving the competition with some gained experience, with the cup and a bottle of "Water from Satu Mare (Pălincă).

Finally I would like to wish this competition a long life and to have an increasing number of participants on the following editions.

ing. Sava Gheorghe

S.C. Apaserv Satu Mare
Director Tehnic
România

Locating pipes


The main materials that can run outside for water distribution networks are:

- Tubes and related parts-iron pressure;
- Cement pipes (are forbidden);
- Reinforced concrete pipes;
- Steel-pipes;
- Rigid PVC-type pipes G (pressure resistant)
- Polyethylene HDPE Pipes

Materials had presented numerous failures in service (ex. steel), materials that have been banned (asbestos cement) or material more difficult to mount were replaced with modern materials like ductile iron and polyethylene.

The importance of determine branching ducts line (route pipelines and branching) is very high in this activity and helps the localization more accurate and pre-location of a fault.

Activity to detect water loss is based on the following aspects:

- Knowledge-branching and pipeline route
- Knowledge of the material and pipe diameter and branching

These data are entered in the noise correlator input calculated based on distance and indicate where is the leak. Then with the microphone (electronic ear) can be listen over the pipeline in place indicated by the noise correlator.

The device pipe is used to locate buried metal piping and cable trays, appliance-based generator-receiver system. The principle of localization is based on the fact that are around of cable or metal pipe, wich are crossed by an electric current, that generates an electromagnetic field. The extent and intensity of this field is determined through a search coil and a receiver. Evaluation of localized field serves to determine the route of the wire.

Connection Method:
- Direct galvanic induced electromagnetic field generator locates
- Clamp-inductively
- Internal antenna inductively

AC cord provides a transmitter module that generates an electric field around it. The receiver has a coil that is placed in close proximity to the electric lines of flux passing through the coil directly into the receiver. The coil produces a small voltage measured by the receiver and displayed on the display.
To make a detection of a pipeline must know his route, length, material, etc..

The new HDPE pipe, PVC, ductile iron are or should be provided with detection wire (wire reinforced in metal tracer). The importance of non-metallic wire for locating pipes is very high.

Going to receive new pipe work and connections I noticed that in most cases these pipes can not be detected (wireless off, very thin existing wired, wireless extended by another thread through direct binding without stripping, etc.). Wire taps have no limit.

For longer employs detection thread and if you want to locate an extension pipe, valve fitting, branch new rendition of the site for various companies to dig.






CONCLUSIONS:

Each non-metallic and metal-pipe (ductile iron is combined with the detection signal leaving rubber rings) must be provided with tracer wire
- Tracer wire must have a minimum thickness of 0.3 mm
- Connections between pieces of wire must be made dezizolând cords and tying them together
The tracer wire is recommended to have contact with the ground (to be stripped and connect to the hydrants, to introduce a metal nail from about 200m to 200m and make the connection thread, the thread of connections must to be linked with wire stripper joint pipeline)
- Wire should be positioned on the pipe (connected trough) to use the method of rendering pipeline depth
- There are situations in which the detection wire can be achieved even if the above conditions are met (for example an area where there are no underground household (cables, pipes, etc.)
- Each new work should be checked if the thread is inserted properly and may be useful to track the location of pipeline
- Project supervisor, builders, etc.. must know the importance of the yarn and how it works

I did the following experiment:
- I lay a 50m long wire, 0.3 mm thick copper
- I did the wired connection galvanically, the other end being kept in air
- I generated a frequency on the line and tried to find receiver
- As long as the wire was not grounding wire could not be detected even at a distance of 1cm
- When I did touch the ground wire could be located with no problems

There are effective devices capable of locating non-metallic pipes?

There are alternatives to wire detection, but some are more expensive and more vague:
• Electronic markers for marking and locating underground utilities routes
• Ground Penetration Radar
• Infrared
• Old method but useful in some cases, when using two electrodes that can determine if there is a buried pipeline
Unquestionably, the work of detection is necessary for utility networks and prevent major problems in yards, especially in cases where the network plans do not correspond with reality, no longer exist or have not been updated.

Technique for locating underground utilities is highly developed in the United States where each state has a so-called Call Before You Dig service, that provides updated information about the utility location. In this way these accidents can be avoided during excavation work.

I hope that in future we can establish an association in Romania to provide such information in each county, because it would reduce the cost of repairing damage caused, and also there would be work-related accidents that cause disability or even death, that can be avoided by using this method.

The normal would be to introduce a law whereby any excavation operation is not done without a preliminary determination process and without providing a site plan.
Eng. Alin Anchidin
SC AQUATIM SA Timişoara
România

WATER LOSSES

One of the major challenges facing water companies in Romania is the high level of water losses, which are either due to real losses (leakage from pipelines transporting or distribution of reservoirs, etc.) or apparent losses (errors of measurement of quantity of water supplied to customers, theft of water, etc..).

Factors Affecting Leakage
• Pressure
• Soil movement
• Pipe deterioration
• Poor quality of materials and workmanship
• Soil characteristics
• Traffic loading
• Stray electrical currents

A good management of water losses depends not only on identifying rehabilitation and improvement priorities for the distribution network , but equally on the introduction of effective methods and practices for assessing, monitoring and controlling of the main elements of non revenue water (NRW): real losses, apparent losses and unbilled consumption.
For a performant management of water losses it is proposed to include in current practices modern methods and tools for monitoring analysis, such as Water Balance and Infrastructure Leakage Indexes.
• Water Balance
• Losses in the infrastructure indices
• Evaluation of water distribution network
• Analysis, diagnosis of water and sewerage system

The reduction of real losses by:

- speed and quality of repairs;
- infrastructure management, pressure management
- establishing an annual program to check the network using special equipment to detect leaks and establishing a proactive maintenance program
- optimization of water supply system by using automation and dispatcher systems
- flow monitoring (district metering areas, flow analysis on each area
- identify potential pressure reduction areas (initial for Craiova and explore pressure reduction opportunities in other branches)
- identify DMA pilot for pressure reduction
- reduce water losses from reservoirs
- reducing water losses on transportation and distribution system(counting the source and the entrance to treatment stations, etc.)..

Reduce the apparent losses by:

- Identification of unauthorized consumers
- Meter installation programme
- replacement of old meters (correlation of consumption with the type of meter used)


Eng. Gabriela Lupăncescu
Compania de Apă Oltenia SA, Craiova

Referinţă:
Water loss - conference proceedings - Volume I, Volume II, Volume III - Water Loss 2007 : Conference Proceedings : Bucharest – Romania : 23-26
September 2007
NRW Guidelines - FOPIP, ISPA measure 2000/RO/16/P/PE/002-05
National Guide of Water and Wastewater Operators, 2008

Did you know that...


-only 1% of the Earth’s drinking water can be consumed? The rest is “stored” in the ice sheet and in glaciers?
- 141 million urban dwellers don’t have access to safe drinking water resources?
- Romania’s water requirement from 2010 has decreseased with 12 billion m³ since 1990, from 20.5 billion m³ water (reported value for 1990), to 8.45 billion m³ water (as recorded in 2010)
and with 1 billion m³ water - 27% of the urban dwellers from around the world don’t have access to piped water at home and they live at at least 1 km distance away from the nearest fresh water resource?
- some 250 to 500 million m³ of drinking water gets lost in many mega cities each year?
- in Romania, the coverage of the waste water collection services is of 54,28%,
- water is the only chemical element capable of existing in a solid, liquid, and gaseous state of aggregation?
- the human body contains 75% water?
- in 2008, in Barcelona, because of the drought, drinking water has been brought with heavy-duty ships?
- Ireland and Great Britain – in 2010, the city of Dublin has been left without water because of the water-leaks?
- Thames Water Company is building a huge desalination plant (900.000 people) in order to ensure water requirements? The company doesn’t allow anymore the usage of rubber pipes and spends £190 million every year to detect and to mend the water-leaks.