Depth of feeling

A waterproofing system that incorporates a network of sensors to detect minute breaches in reservoirs could save the water industry millions of pounds, according to its UK developer.

The Hylam IQ system has been dubbed the ‘intelligent membrane’ by thermoplastics specialist DRC Polymers, which has just completed its first installation at a reservoir in Cumbria.

Managing director Ken Bray claimed the waterproofing system could significantly cut the cost of pinpointing and repairing leaks in reservoirs — an expensive and disruptive process.

The system’s sensors attach to the walls of a reservoir at regular intervals. These are connected by wires to a terminal and are overlaid with a conventional industry standard waterproof membrane which is laminated with a conductive polypropylene. This laminate has a known resistivity which makes the system very accurate.

Every 3000m2 of surface, an injector plate is attached which engineers use to charge the surface of the membrane during testing. To test its integrity a voltage is applied through the plates which gives a potential reading across all of the sensors. The voltage is adjusted to make sure all sensors are giving the same reading. If the membrane is breached by water, current will pass through to the conductive laminate and be detected as an irregular electrical reading from the sensors in the affected area.

This development provides an alternative to existing waterproofing techniques. Though most modern waterproofing systems are liquidbased, they have a number of disadvantages, according to Bray.

‘First, liquid waterproofing is not too good at accommodating structural movement,’ he said. ‘This means water companies have to invest in extremely high-specification reinforced concrete to minimise movement.’

Second, liquid waterproofing can only be applied when the concrete surface is clean, dry and within a certain temperature range.

Before the development of liquid waterproofing, the only way of keeping reservoirs watertight was to fix membranes in place. Though these were able to cope with structural shifts, they had the disadvantage that, if there was a leak, the water could find its way between the plates and the source of the leak would be difficult to locate.

DRC Polymers spent three years trying to develop a system that couples the advantages of membrane panels with the integrity of liquid waterproofing. The resultant Hylam IQ system is able to pinpoint a leak to within a 3m2 area, claimed Bray.

‘It is an important development because before now, for reservoirs that are many thousands of square metres in size, if you had a leak the only solution has been to excavate the lot,’ said Bray.

‘It also means utilities can downgrade the specifications of their new reservoirs as they don’t have to be as stable as for liquid waterproofing.’ The system can be customised to the needs of individual utilities.

The software that analyses the sensors’ signals is self-diagnostic and could be set up to alert an engineer’s mobile phone if the signals deviate from certain parameters. Hylam IQ has just been installed at the newly-constructed Demings Moss reservoir in Cumbria, operated by United Utilities.

The firm is looking to use the system at a number of other sites. ‘It’s early days, but given the number of service reservoirs in this country, the potential savings are phenomenal,’ said Bray.