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Thames Barrier

The Thames Barrier was completed in 1982, spans a 520 metre stretch of the River Thames downstream of central London and is operated by the Environment Agency. The barrier has 10 steel gates fitted between piers that can be rotated into position across the River Thames if a tidal surge is predicted. The gates weigh around 3,300 tonnes, the barrier needs to be ready for operation at any time and ongoing maintenance and improvements to the barrier systems are critical to provide the required level of reliability.

VolkerStevin has worked with the client and their design teams and provided considerable benefits from ECI input on a number of contracts at the Barrier since April 2005. The team has worked together to develop unique solutions that satisfied site specific constraints, HSE&Q and other client requirements.

The continuity afforded from 6 years involvement with client and design teams has resulted in exceptional mutual trust & cooperation between all parties.

VolkerStevin has carried out works within the gates and designed and installed UPVC access platforms to facilitate movement within the gates.

We have established fully self sufficient working platforms for the stripping and re-coating of the external gate surfaces. These are flexible and could be moved to suit shipping and/or gate use requirements.

VolkerStevin has also carried out maintenance on the existing Cathodic Protection system as well as carrying out trials using an impressed current Cathodic Protection system.

Recently VolkerStevin were engaged by the barrier team to help develop a safe method and system to replace the Macalloy bars, provide a multifunctional monitoring system and allow the gate arm bearings to be greased for the first time. The Macalloy bars provide support to the gate arm bearing system. The bars, under 910 KN of stress, are accessed from a very confined trunnion shaft within the piers. The solution was to fix a limpet cofferdam to the gate arm that allowed access to the bar end.

VolkerStevin produced a full scale mock up of the structure and was able to demonstrate a bar replacement sequence that was acceptable to the design team. This mock up was used to provide training to the operatives prior to the main works starting on site improving the efficiency and safety of the operation and reducing cost by reducing the learning time under live/tidal conditions.

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