Infiltration detection – needs a bright spark: PRESENTATION ONLY
Henley, P., WRc, UK
(free)
At the recent WWT Infrastructure Conference in Birmingham Steve Kaye from Anglian Water reported that 70% of Anglian Waters sewerage catchments had significant problems with infiltration. His company is not alone with this issue particularly in the South of England.
Infiltration into sewerage networks leads to many problems that impact on customers and the environment such as flooding incidents, 24/7 tankering from overwhelmed pumping stations, failed treatment work consents and discharges from CSO’s.
In 2014, one water company representative in the South of England said they had had only one flooding event that winter, it had started in November and had ended in March. So the challenge the water companies face is to locate where the infiltration is getting into their sewer networks and how to fix them all within considerable cost restraints.
CCTV can detect major infiltration points but typically during high ground water events the pipes are surcharged so preventing an adequate survey. Increasingly companies are looking towards technologies that use electrical conductivity such as Electro Scan to help them solve their problems.
Electro Scan works by creating a small electrical current escaping from the insulating surcharged pipe to create a circuit with an earthing rod enabling the location of the defect in the pipe to be pinpointed. A sufficiently focussed electrical current can detect the size of defects and the electrical return is quantified to enable defects to be scored by their potential to leak. This enables the asset owner to target rehabilitation on the pipes with the greatest potential to cause infiltration. Another benefit of this technique is that as the pipe is surcharged to complete the survey it thereby replicates ground water event conditions enabling infiltration surveys to be carried out all year round
