Leakage Detection In Underground Distribution Pipes

LEAKAGE DETECTION IN UNDERGROUND DISTRIBUTION PIPES

Leakage detection methods:

(i) By direct observation

(ii) By using sounding rods

(iii) By plotting hydraulic gradient line

(iv) By using waste detection meters.

1. By direct observations :

• Wet soft spots on unpaved ground, grasses, emergence of springs at odd places indicates leakage from underground pipes.

• Such indications will be available when pipes are laid below loamy or clayey soils.

•  However, direct observation is difficult in sandy soils.

2. By using sounding rods :

• A sharp pointed metal rod is thrust into the ground along the pipe line and pulled up for inspection.

• Its moist or muddy point indicates leakage.

• The sound of escaping water can be heard by placing the ear on top of the inserted rod or by using magnifying instruments -aquaphone or sonoscope.

• The sound hearing should be done during night hours.

3. By plotting hydraulic gradient line

• The pressures at various points along a suspected pipeline are measured and the HGL is plotted.

• Any kink or change in slope of the HGL will indicate the location of leakage.

4. By using waste detection meters

• These meters measure the unusually high flows passing through the water mains during periods of low consumption (during night or early morning)

• The unusual flow indicates leakage.

• This test is conducted during night hours.

Method: The suspected locality is isolated.

• The supplies to all other areas are closed down except the suspected area.

• The meter is fitted at the head of main supply pipe and flow is recorded.

• The laterals and branches of the locality are progressively shut off.

• The shut off that indicates a large disproportionate drop in flow indicates leakage.

• Steps are taken to rectify the defects.

Deacon's waster water detection meters are widely used as they are sensitive and accurate. The water passing through the meter forces down a brass disc which moves a pencil point up and down on a graph paper mounted on a drum. It automatically records the discharge of water.