Raised chambers housing flow gauges for London's new multi-million pound ‘super sewer’ have been secured with intruder-resistant turret tops.

Thames Water's extension to the Lee Tunnel was opened earlier this year by Foreign Secretary Boris Johnson before he departed his former role as London Mayor. The 4.3 mile-long £678 million project took four years to build and was designed to stop sewage flushing into the River Thames and River Lee. Perimeter security expert Zaun had already secured the access points to the tunnel extension with its most intruder-resistant product, ArmaWeave, installed by Zaun subsidiary Binns Fencing.

ArmaWeave’s unique properties add substantial resistance to cutting attacks with hand, powered and non-contact tools.  The tight mesh pattern provides no climbing aids, again limiting the potential for intrusion. Zaun designed two bespoke ‘cages’ from ArmaWeave with special fixings and topped with 980 razor coil to protect the flow gauge chambers.

On average 39 million tonnes of untreated sewage mixed with rain water gets discharged into the River Thames from overloaded treatment works and combined sewer outfalls every year. The biggest of these outfalls, at Abbey Mills pumping station, has been discharging 16 million tonnes of sewage per year to the River Lee. The £678 million Lee Tunnel – the largest single project in the history of the privatised water industry in England and Wales, and the deepest ever bored under London at 75 metres deep – will capture this sewage to keep it out of the River Lee.

The Lee Tunnel connects the Abbey Mills Water Treatment Centre to Beckton Sewage Treatment Works, Europe's largest such site, both if which are also secured by Zaun perimeter protection. The Thames Tideway Tunnel will connect to the Lee Tunnel and will capture sewage from the remaining 34 combined sewer overflows, keeping it out of the River Thames.