Leakage detection and control the pipe networks

Contents

• Introduction

• Causes of leaks and benefits of leakage control

• Leakage management strategy

• Economic level of leakage

• Leak detection and control program

Introduction

•Leakage

     Loss of water by unintentional escape from the

     distribution network                                                       Can range from slow leak or “drip” to “main break”

•Break/Burst

•A large opening caused when a network component

     fails due to excessive high loads, high internal pressure,

•corrosion or a combination of above factors.

•Effect of Leakage

•  Primary economic loss – cost of raw water, its

    treatment, and its transportation.

•  Damage of the pipe network and other properties

    e.g. - erosion of the pipe bedding leading to pipe breaks,

     foundation of roads and buildings

•  Risk to public health caused by contaminants entering

    the pipe through leak openings.

 

Benefits of leak detection and repair

• Water savings

• Energy savings (treatment and pumping)

• Reduced O&M costs (reduced salary costs and

    outage times)

• Reduced consumer complaints and improved public relations

• Reduced property damage and reduced risk of

   contamination

Leakage Management Strategies of two main groups

• In general, leakage management strategies can be

•   - Passive Leakage Control (Reactive Control)

•   - Active Leakage Control (Proactive Control)

•Passive Leakage Control (PLC) is a reaction to visible leakage due to bursts or drops in pressure, which are usually reported by customers or noted by the company’s staff.

Passive leakage control

•Passive leakage control is a procedure whereby   water loss is tackled when leakage is visible or when problem are reported from the public.

•The adoption of this policy minimizes day to day operating costs of leakage detection, but increases the risk of water being wasted.

• This policy is applicable if:

       - The costs of leakage detection are high

       - The costs of production are low

       - Bursts are readily visible and easily repaired.

Active leakage control

• Active Leakage Control (ALC) refers to set of procedures and steps taken by the water utilities (with special team of dedicated staff) to monitor, repair and maintain the leakage level as an regular activity. This includes:

    - Regular survey (sounding, waste metering)

    - Leakage monitoring in zones or sectors (DMA monitoring and management)

Leakage run time

•The level of leakage will depend on the flow rate and the time for which they run. The run time comprises of three elements.

•AWARENESS TIME: Time taken for the water supplier to be aware of the leak or burst.

•LOCATION TIME: Time taken to locate the leak   or burst once the water supplier is aware of its existence.

•REPAIR TIME: Time taken to make the repair, once the location has been pinpointed.

Leak detection and location

• Leak detection

   “narrowing down” of a leak or leaks to  a section of the pipe network

    may be carried out routinely

•Leak location

    identification of the position of a leak prior to

    excavation and repair, although finding the

    exact location cannot be guaranteed.

•location surveys may be carried out with or

    without prior detection activity

Leak detection techniques

•There are a number of techniques to detect where leakage is taking place in the network, including:

•sub-division of DMAs into smaller areas by    temporarily closing valves or by installing meters;

       - variations of the traditional step-test;

       - the use of leak localizers;

       - sounding surveys.

Main steps in leak detection and control

•Data collection

         Network data, leak frequency and repair  data,Pipe rehab data, operation and maintenance             system

•Network evaluation

•Physical leak detection (detection in the field)

•Planning and implementation of repair program

•Network maintenance and rehabilitation program

Methods of leak and break location

•  Acoustic

•  Acoustic with correlation

•  Infrared thermography

•  Chemical

•  Mechanical

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 any     material. Metallic pipe is much better sound conductor

      than non-metallic pipe.

• Soil type

     - sand is normally a

       good conductor of sound; clay is a poor conductor.

• Surface type

     - the surface on which the sounding instrument is placed

       also influences how the sound travels.

Sustained Leakage Management

•It is vital in leakage management that the advances

•made in water loss reduction are sustained.

     This can be achieved by:

     - ensuring appropriate staffing levels

     - staff education and training

     - operation and maintenance

     - assessing and monitoring performance

     - strategic monitoring

   - facilities monitoring and maintenance

     - operational performance monitoring