Southern Water is trialling new technology to overcome a long-standing problem in leak detection.
A major difficulty in repairing a leaking sewer fully surcharged with groundwater is finding where the leaks are in the first place.
Traditionally, water companies use remotely-controlled CCTV units to travel inside the sewer and identify leaks but they have to wait weeks, sometimes months, before groundwater levels drop to an appropriate level to allow filming to take place. There is only a short, finite window for traditional camera surveys to be effective – when the groundwater level is at the top of the sewer and falling.
But Southern Water is trialling a new technique to survey sewers fully surcharged with groundwater. If successful, this will bring quicker relief to towns and villages affected by sewer flooding as sewer repairs could then be scheduled to be carried out more quickly, protecting customers’ toilet, kitchen and bathroom facilities.
The Worthing-based company chose the often flood-affected village of Hambledon, 13 miles north of Portsmouth, for its trial, deliberately flooding a long length of sewer from Lotts Store to the Wastewater Pumping Station at Bury Lodge to test the method.
Instead of using CCTV cameras, the new technique, named Electro Scan, involves pushing or winching a small torpedo-shaped probe through a surcharged pipe. The probe emits an electrical current which if earthed indicates a pathway and therefore a potential point of leakage. Depending upon the signal, the severity of the leakage can be interpreted. For infiltration purposes this offers a physical test of the pipe’s watertightness that cannot be achieved by CCTV.
Said Keith Savage, Southern Water's Sewer Rehabilitation Manager: "It’s a German technology which has only recently been made available in the UK but has proven itself to be extremely successful elsewhere. If successful, this will be a real bonus for the 60 towns and villages across our region which suffer from groundwater infiltration of the sewers.
"We are now moving the trial on to Winchelsea Beach in Sussex to confirm if we can use this new technology extensively."