Term paper Leakage Control

Leakage Control

Prepared by:1- Ibraheem Abu Sultan2-Hassan AlTaweel

Supervisor Dr. Sari abusharar

Nov.2012

1

Term paper Leakage Control

Contents

• Introduction

• Causes of leaks and benefits of leakage control

• Leakage management strategy

• Economic level of leakage

• Leak detection and control program

• Methods of leak and break location

• Difficulties in locating leaks

• Leakage repair techniques

• Case study

2

Term paper Leakage Control

3

Term paper Leakage Control

Introduction

Worldwide global water consumption has tripled since 1950. In 2006 it surpassed 4,300 km3 per year, the equivalent to 30% of the world's endowment of renewable water. In the twentieth century, global water consumption rose six fold between 1900 and 1995, more than double the rate of population growth. Water abstractions for irrigation have also increased by 75% since 1960 and it is estimated that 20-30% of the water used is wasted due to evaporation and over irrigation. Smart cities monitor water supply and distribution

Smart cities must monitor water supply and distribution to ensure that there is sufficient access for citizen and industry use and also to save money. However, as we pointed above, water is becoming a scarcer resource due to many reasons:

• Increased city populations mean increased demand for water • Climactic changes have reduced rainfall forecasts • Traditional water extraction methods have depleted available water

from some local sources. Water leakage problems: sensor technology solutionsThe problem of water must be faced, not only in cities but houses because every drop counts. Wireless Sensor Networks provide the technology for cities to more accurately monitor their water pipe systems and identify their greatest water loss risks. Cities that are addressing water leakages with sensor technology are generating high savings from their investment. Tokyo, for example, has calculated they save $USD170 million each year by detecting water leakage problems early. Libelium’s Smart Metering Sensor Board includes a water flow sensor that can detect pipe flow rates ranging from 0.15 to 60 liters/minute. The system can report pipe flow measurement data regularly, as well as send automatic alerts if water use is outside of an expected normal range. This allows a smart city to identify the location of leaking pipes and prioritize repairs based on the amount of water loss that could be prevented

20 % in United Kingdom, Spain, Malta, and the Czech Republic 25% in Rome. Nearly 50% in London and Vietnam To get it worse, the European Environment Agency forecasts that by 2030 – in less than 20 years time! – global demand for water will increase by 40%.

4

Term paper Leakage Control

Water leakage problems: sensor technology solutionsThe problem of water must be faced, not only in cities but houses because every drop counts. Wireless Sensor Networks provide the technology for cities to more accurately monitor their water pipe systems and identify their greatest water loss risks.

Fig.1 The water consumption distribution per use and continent:

5

Term paper Leakage Control

Leakage- Loss of water by unintentional escape from thedistribution network- Can range from slow leak or “drip” to “main break”Break/Burst- A large opening caused when a network componentfails due to excessive high loads, high internal pressure,corrosion or a combination of above factors.Very often, leakage is the main component of water loss

Effect of Leakage• Primary economic loss – cost of raw water, itstreatment, and its transportation.• Damage of the pipe network and other propertiese.g. - erosion of the pipe bedding leading to pipe breaks,- foundation of roads and buildings• Risk to public health caused by contaminants enteringthe pipe through leak openings.

Volume of the water lost by leakage will depend• Characteristics of the pipe network• Leak detection and repair policy practised, such as:• the pressure in the network.• whether soil allows water to be visible at the surface• “awareness” time (how quickly the loss is noticed);• repair time (how quickly the loss is repaired)

Water Audit of a water supply

Water Audit of a water supply scheme can be defined as the assessment of the capacity of total water produced by the Water Supply Authority and the actual quantity of water distributed throughout the area of service of the Authority, thus leading to an estimation of the losses.

6

Term paper Leakage Control

Fig. 2 UNACOUNTED FOR WATER

The water losses can be termed into two categories.1. Physical losses (Technical losses)

This is mainly due to leakage of water in the net work and comprises of physical losses frompipes, joints & fittings, reservoirs & overflows of reservoirs & sumps.

2. Non-physical losses (Non-technical losses/Commercial losses)

Theft of water through illegal, already disconnected connections, under-billing eitherdeliberately or through defective meters, water wasted by consumer through open or leakytaps, errors in estimating flat rate consumption, public stand Free supply, fire-hydrants, use in public toilets, parks etc.

7

Term paper Leakage Control

Fig. 3 picture of water losses

Fig. 4 picture of water losses in water network

8

Term paper Leakage Control

Fig. 5 picture of break in water network

Common factors influencing leakages

Ground movementPipe corrosionHeavy traffic loadingsHigh system pressureDamage due to excavationPipe ageWinter temperatureDefects in pipesPoor quality of jointsGround conditionsPoor quality of workmanship

Benefits of leak detection and repair

• Water savings• Energy savings (treatment and pumping)• Reduced O&M costs (reduced salary costs andoutage times)• Reduced consumer complaints and improvedpublic relations• Reduced property damage and reduced risk ofContamination

9

Term paper Leakage Control

Leakage Management Strategies

In general, leakage management strategies can beof two main groups:- Passive Leakage Control (Reactive Control)- Active Leakage Control (Proactive Control)• Passive Leakage Control (PLC) is a reaction tovisible leakage due to bursts or drops in pressure,which are usually reported by customers or notedby the company’s staff.

Active Leakage Control (ALC) refers to set ofprocedures and steps taken by the water utilities(with special team of dedicated staff) to monitor,repair and maintain the leakage level as anregular activity. This includes:- Regular survey (sounding, waste metering)- Leakage monitoring in zones or sectors (DMAmonitoring and management)

Economic level of leakage

For a given network reducing leakage to zerowould be virtually impossible and enormouslyexpensive for the consumers.• Water companies strike a balance between thecost of reducing leakage and the value of watersaved.• The level of leakage at which it would cost moreto make further reductions in leakage than toproduce the water from another source is knownas "Economic Level of Leakage (ELL)".

Leak detection and location

• Leak detection- “narrowing down” of a leak or leaks to asection of the pipe network- may be carried out routinely• Leak location- identification of the position of a leak prior to

10

Term paper Leakage Control

excavation and repair, although finding theexact location cannot be guaranteed.- location surveys may be carried out with orwithout prior detection activity

Leak detection techniques

There are a number of techniques to detect whereleakage is taking place in the network, including:- sub-division of DMAs into smaller areas bytemporarily closing valves or by installing meters;- variations of the traditional step-test;- the use of leak localizers;- sounding surveys.

Fig. 6 District Metered Area (DMA)

11

Term paper Leakage Control

Main steps in leak detection and control

Data collection- network data, leak frequency and repair data,pipe rehab data, operation and maintenancesystem• Network evaluation• Physical leak detection (detection in the field)• Planning and implementation of repair program• Network maintenance and rehabilitation program

Factors affecting leak sounds

• Pressure- It should be 15 psi (~10 m) or more for sonic leak detection.• Pipe material and size- Sonic techniques can be used for pipe and fittings of anymaterial. Metallic pipe is much better sound conductorthan non-metallic pipe.• Soil type- Influences the amount of sound transmitted to thesurface. Observations indicate that sand is normally agood conductor of sound; clay is a poor conductor.• Surface type- the surface on which the sounding instrument is placedalso influences how the sound travels.

Water Leak Detector.

Use Ground plate for street surfaces, sidewalks and concrete slabs.Use pointed red or boring bars (push rods) in soft dirt and grass covered areas.Listen every 50-60cm. Do not adjust volume and listen for 5-10 seconds only

12

Term paper Leakage Control

Fig.7 Listening devices and leak-noise correlator

Fig.8 Leak Noise Correlator

Fig.9 Visible Display Detectors

13

Term paper Leakage Control

Difficulties in locating leaks

1. Sources of Interference- a variety of common environmental conditionscan interfere the acoustic method of leakdetection.- variation in soil properties, moisture, watertable, water pressure- locating leaks requires trained andexperienced operators and can be problematicin noisy or geologically complexed areas

2. Access to test points- distance between a detector and the leak maynot be optimal in many cases.

3. Pipe location- location of pipe may be difficult in oldernetworks.- existing records may be incomplete and oflimited use

4. Plastic pipes- leaks are difficult to determine in segmentscontaining plastic pipes.- plastics dampen vibrations so noise caused byleaks or breaks does not propagate as far asmetal pipes.

Leakage Repair Techniques

There are a number of different techniques for repairing pipes that leak. These techniquesdepend on the severity of leak, type of break in the pipe, the condition of the pipe and thepipe material.A repair clamp to cover the defect.A cut out of the defective section of pipe work/fittings & replacement with a short lengthof pipe.Relay/Renewal of the whole or section of the pipe.

14

Term paper Leakage Control

Case Study

Leakage in water networks in Nusirat municipality

The Nusirat camp is the largest camp in the middle area of Gaza strip , the boundary of Nusirat is Wadi Gaza from north, the sea from west, Salah El Dien road from the east and El Zawayda from the north.

The area of Nusirat 9850 donum with population of about 70000 inhabitant, the topography vary from 5 to 39 m above sea level .

The source of the water is from 7 wells in the boundary of the Nusirat , 5 wells in el Zahra area and also from macarot company.

The total length of waternetwork is about 100 km and the diameter of the pipes vary from 300 mm to 50 mm.

15

Term paper Leakage Control

Table 1 Percentage of losses in El Nusirat municipality Water network

16

Term paper Leakage Control

References

1- Monthly reports of Health and Water department in El Nusirat Municipality.

2-WHO-World Health Organisation, Leakage Management and Control- A Best Practice Manual, WHO,Geneva,2001

3- Archa Gopan,Suja.R,Dr.J.Letha, Pressure Control for Leakage Minimization In Water Distribution Network ,2007

4-Saroj Sharma, Leakage Management & Control, The Netherlands,2008

17